blob: 99cde4a2a59df99ce7982fa723c9223cd5663303 [file] [log] [blame]
/* Diagnostic routines shared by all languages that are variants of C.
Copyright (C) 1992-2021 Free Software Foundation, Inc.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
version.
GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3. If not see
<http://www.gnu.org/licenses/>. */
#define INCLUDE_STRING
#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "target.h"
#include "function.h"
#include "tree.h"
#include "c-common.h"
#include "memmodel.h"
#include "tm_p.h"
#include "diagnostic.h"
#include "intl.h"
#include "stringpool.h"
#include "attribs.h"
#include "asan.h"
#include "gcc-rich-location.h"
#include "gimplify.h"
#include "c-family/c-indentation.h"
#include "c-family/c-spellcheck.h"
#include "calls.h"
#include "stor-layout.h"
#include "tree-pretty-print.h"
/* Print a warning if a constant expression had overflow in folding.
Invoke this function on every expression that the language
requires to be a constant expression.
Note the ANSI C standard says it is erroneous for a
constant expression to overflow. */
void
constant_expression_warning (tree value)
{
if (warn_overflow && pedantic
&& (TREE_CODE (value) == INTEGER_CST || TREE_CODE (value) == REAL_CST
|| TREE_CODE (value) == FIXED_CST
|| TREE_CODE (value) == VECTOR_CST
|| TREE_CODE (value) == COMPLEX_CST)
&& TREE_OVERFLOW (value))
pedwarn (input_location, OPT_Woverflow, "overflow in constant expression");
}
/* The same as above but print an unconditional error. */
void
constant_expression_error (tree value)
{
if ((TREE_CODE (value) == INTEGER_CST || TREE_CODE (value) == REAL_CST
|| TREE_CODE (value) == FIXED_CST
|| TREE_CODE (value) == VECTOR_CST
|| TREE_CODE (value) == COMPLEX_CST)
&& TREE_OVERFLOW (value))
error ("overflow in constant expression");
}
/* Print a warning if an expression result VALUE had an overflow
in folding and its operands hadn't. EXPR, which may be null, is
the operand of the expression.
Invoke this function on every expression that
(1) appears in the source code, and
(2) is a constant expression that overflowed, and
(3) is not already checked by convert_and_check;
however, do not invoke this function on operands of explicit casts
or when the expression is the result of an operator and any operand
already overflowed. */
void
overflow_warning (location_t loc, tree value, tree expr)
{
if (c_inhibit_evaluation_warnings != 0)
return;
const char *warnfmt = NULL;
switch (TREE_CODE (value))
{
case INTEGER_CST:
warnfmt = (expr
? G_("integer overflow in expression %qE of type %qT "
"results in %qE")
: G_("integer overflow in expression of type %qT "
"results in %qE"));
break;
case REAL_CST:
warnfmt = (expr
? G_("floating point overflow in expression %qE "
"of type %qT results in %qE")
: G_("floating point overflow in expression of type %qT "
"results in %qE"));
break;
case FIXED_CST:
warnfmt = (expr
? G_("fixed-point overflow in expression %qE of type %qT "
"results in %qE")
: G_("fixed-point overflow in expression of type %qT "
"results in %qE"));
break;
case VECTOR_CST:
warnfmt = (expr
? G_("vector overflow in expression %qE of type %qT "
"results in %qE")
: G_("vector overflow in expression of type %qT "
"results in %qE"));
break;
case COMPLEX_CST:
if (TREE_CODE (TREE_REALPART (value)) == INTEGER_CST)
warnfmt = (expr
? G_("complex integer overflow in expression %qE "
"of type %qT results in %qE")
: G_("complex integer overflow in expression of type %qT "
"results in %qE"));
else if (TREE_CODE (TREE_REALPART (value)) == REAL_CST)
warnfmt = (expr
? G_("complex floating point overflow in expression %qE "
"of type %qT results in %qE")
: G_("complex floating point overflow in expression "
"of type %qT results in %qE"));
else
return;
break;
default:
return;
}
bool warned;
if (expr)
warned = warning_at (loc, OPT_Woverflow, warnfmt, expr, TREE_TYPE (expr),
value);
else
warned = warning_at (loc, OPT_Woverflow, warnfmt, TREE_TYPE (value),
value);
if (warned)
suppress_warning (value, OPT_Woverflow);
}
/* Helper function for walk_tree. Unwrap C_MAYBE_CONST_EXPRs in an expression
pointed to by TP. */
static tree
unwrap_c_maybe_const (tree *tp, int *walk_subtrees, void *)
{
if (TREE_CODE (*tp) == C_MAYBE_CONST_EXPR)
{
*tp = C_MAYBE_CONST_EXPR_EXPR (*tp);
/* C_MAYBE_CONST_EXPRs don't nest. */
*walk_subtrees = false;
}
return NULL_TREE;
}
/* Warn about uses of logical || / && operator in a context where it
is likely that the bitwise equivalent was intended by the
programmer. We have seen an expression in which CODE is a binary
operator used to combine expressions OP_LEFT and OP_RIGHT, which before folding
had CODE_LEFT and CODE_RIGHT, into an expression of type TYPE. */
void
warn_logical_operator (location_t location, enum tree_code code, tree type,
enum tree_code code_left, tree op_left,
enum tree_code ARG_UNUSED (code_right), tree op_right)
{
int or_op = (code == TRUTH_ORIF_EXPR || code == TRUTH_OR_EXPR);
int in0_p, in1_p, in_p;
tree low0, low1, low, high0, high1, high, lhs, rhs, tem;
bool strict_overflow_p = false;
if (!warn_logical_op)
return;
if (code != TRUTH_ANDIF_EXPR
&& code != TRUTH_AND_EXPR
&& code != TRUTH_ORIF_EXPR
&& code != TRUTH_OR_EXPR)
return;
/* We don't want to warn if either operand comes from a macro
expansion. ??? This doesn't work with e.g. NEGATE_EXPR yet;
see PR61534. */
if (from_macro_expansion_at (EXPR_LOCATION (op_left))
|| from_macro_expansion_at (EXPR_LOCATION (op_right)))
return;
/* Warn if &&/|| are being used in a context where it is
likely that the bitwise equivalent was intended by the
programmer. That is, an expression such as op && MASK
where op should not be any boolean expression, nor a
constant, and mask seems to be a non-boolean integer constant. */
STRIP_ANY_LOCATION_WRAPPER (op_right);
if (TREE_CODE (op_right) == CONST_DECL)
/* An enumerator counts as a constant. */
op_right = DECL_INITIAL (op_right);
tree stripped_op_left = tree_strip_any_location_wrapper (op_left);
if (!truth_value_p (code_left)
&& INTEGRAL_TYPE_P (TREE_TYPE (op_left))
&& !CONSTANT_CLASS_P (stripped_op_left)
&& TREE_CODE (stripped_op_left) != CONST_DECL
&& !warning_suppressed_p (op_left, OPT_Wlogical_op)
&& TREE_CODE (op_right) == INTEGER_CST
&& !integer_zerop (op_right)
&& !integer_onep (op_right))
{
bool warned;
if (or_op)
warned
= warning_at (location, OPT_Wlogical_op,
"logical %<or%> applied to non-boolean constant");
else
warned
= warning_at (location, OPT_Wlogical_op,
"logical %<and%> applied to non-boolean constant");
if (warned)
suppress_warning (op_left, OPT_Wlogical_op);
return;
}
/* We do not warn for constants because they are typical of macro
expansions that test for features. */
if (CONSTANT_CLASS_P (fold_for_warn (op_left))
|| CONSTANT_CLASS_P (fold_for_warn (op_right)))
return;
/* This warning only makes sense with logical operands. */
if (!(truth_value_p (TREE_CODE (op_left))
|| INTEGRAL_TYPE_P (TREE_TYPE (op_left)))
|| !(truth_value_p (TREE_CODE (op_right))
|| INTEGRAL_TYPE_P (TREE_TYPE (op_right))))
return;
/* The range computations only work with scalars. */
if (VECTOR_TYPE_P (TREE_TYPE (op_left))
|| VECTOR_TYPE_P (TREE_TYPE (op_right)))
return;
/* We first test whether either side separately is trivially true
(with OR) or trivially false (with AND). If so, do not warn.
This is a common idiom for testing ranges of data types in
portable code. */
op_left = unshare_expr (op_left);
walk_tree_without_duplicates (&op_left, unwrap_c_maybe_const, NULL);
lhs = make_range (op_left, &in0_p, &low0, &high0, &strict_overflow_p);
if (!lhs)
return;
/* If this is an OR operation, invert both sides; now, the result
should be always false to get a warning. */
if (or_op)
in0_p = !in0_p;
tem = build_range_check (UNKNOWN_LOCATION, type, lhs, in0_p, low0, high0);
if (tem && integer_zerop (tem))
return;
op_right = unshare_expr (op_right);
walk_tree_without_duplicates (&op_right, unwrap_c_maybe_const, NULL);
rhs = make_range (op_right, &in1_p, &low1, &high1, &strict_overflow_p);
if (!rhs)
return;
/* If this is an OR operation, invert both sides; now, the result
should be always false to get a warning. */
if (or_op)
in1_p = !in1_p;
tem = build_range_check (UNKNOWN_LOCATION, type, rhs, in1_p, low1, high1);
if (tem && integer_zerop (tem))
return;
/* If both expressions have the same operand, if we can merge the
ranges, ... */
if (operand_equal_p (lhs, rhs, 0)
&& merge_ranges (&in_p, &low, &high, in0_p, low0, high0,
in1_p, low1, high1))
{
tem = build_range_check (UNKNOWN_LOCATION, type, lhs, in_p, low, high);
/* ... and if the range test is always false, then warn. */
if (tem && integer_zerop (tem))
{
if (or_op)
warning_at (location, OPT_Wlogical_op,
"logical %<or%> of collectively exhaustive tests is "
"always true");
else
warning_at (location, OPT_Wlogical_op,
"logical %<and%> of mutually exclusive tests is "
"always false");
}
/* Or warn if the operands have exactly the same range, e.g.
A > 0 && A > 0. */
else if (tree_int_cst_equal (low0, low1)
&& tree_int_cst_equal (high0, high1))
{
if (or_op)
warning_at (location, OPT_Wlogical_op,
"logical %<or%> of equal expressions");
else
warning_at (location, OPT_Wlogical_op,
"logical %<and%> of equal expressions");
}
}
}
/* Helper function for warn_tautological_cmp. Look for ARRAY_REFs
with constant indices. */
static tree
find_array_ref_with_const_idx_r (tree *expr_p, int *, void *)
{
tree expr = *expr_p;
if ((TREE_CODE (expr) == ARRAY_REF
|| TREE_CODE (expr) == ARRAY_RANGE_REF)
&& (TREE_CODE (fold_for_warn (TREE_OPERAND (expr, 1)))
== INTEGER_CST))
return integer_type_node;
return NULL_TREE;
}
/* Subroutine of warn_tautological_cmp. Warn about bitwise comparison
that always evaluate to true or false. LOC is the location of the
==/!= comparison specified by CODE; LHS and RHS are the usual operands
of this comparison. */
static void
warn_tautological_bitwise_comparison (const op_location_t &loc, tree_code code,
tree lhs, tree rhs)
{
if (code != EQ_EXPR && code != NE_EXPR)
return;
/* Extract the operands from e.g. (x & 8) == 4. */
tree bitop;
tree cst;
tree stripped_lhs = tree_strip_any_location_wrapper (lhs);
tree stripped_rhs = tree_strip_any_location_wrapper (rhs);
if ((TREE_CODE (lhs) == BIT_AND_EXPR
|| TREE_CODE (lhs) == BIT_IOR_EXPR)
&& TREE_CODE (stripped_rhs) == INTEGER_CST)
bitop = lhs, cst = stripped_rhs;
else if ((TREE_CODE (rhs) == BIT_AND_EXPR
|| TREE_CODE (rhs) == BIT_IOR_EXPR)
&& TREE_CODE (stripped_lhs) == INTEGER_CST)
bitop = rhs, cst = stripped_lhs;
else
return;
tree bitopcst;
tree bitop_op0 = fold_for_warn (TREE_OPERAND (bitop, 0));
if (TREE_CODE (bitop_op0) == INTEGER_CST)
bitopcst = bitop_op0;
else {
tree bitop_op1 = fold_for_warn (TREE_OPERAND (bitop, 1));
if (TREE_CODE (bitop_op1) == INTEGER_CST)
bitopcst = bitop_op1;
else
return;
}
/* Note that the two operands are from before the usual integer
conversions, so their types might not be the same.
Use the larger of the two precisions and ignore bits outside
of that. */
int prec = MAX (TYPE_PRECISION (TREE_TYPE (cst)),
TYPE_PRECISION (TREE_TYPE (bitopcst)));
wide_int bitopcstw = wi::to_wide (bitopcst, prec);
wide_int cstw = wi::to_wide (cst, prec);
wide_int res;
if (TREE_CODE (bitop) == BIT_AND_EXPR)
res = bitopcstw & cstw;
else
res = bitopcstw | cstw;
/* For BIT_AND only warn if (CST2 & CST1) != CST1, and
for BIT_OR only if (CST2 | CST1) != CST1. */
if (res == cstw)
return;
binary_op_rich_location richloc (loc, lhs, rhs, false);
if (code == EQ_EXPR)
warning_at (&richloc, OPT_Wtautological_compare,
"bitwise comparison always evaluates to false");
else
warning_at (&richloc, OPT_Wtautological_compare,
"bitwise comparison always evaluates to true");
}
/* Given LOC from a macro expansion, return the map for the outermost
macro in the nest of expansions. */
static const line_map_macro *
get_outermost_macro_expansion (location_t loc)
{
gcc_assert (from_macro_expansion_at (loc));
const line_map *map = linemap_lookup (line_table, loc);
const line_map_macro *macro_map;
do
{
macro_map = linemap_check_macro (map);
loc = linemap_unwind_toward_expansion (line_table, loc, &map);
} while (linemap_macro_expansion_map_p (map));
return macro_map;
}
/* Given LOC_A and LOC_B from macro expansions, return true if
they are "spelled the same" i.e. if they are both directly from
expansion of the same non-function-like macro. */
static bool
spelled_the_same_p (location_t loc_a, location_t loc_b)
{
gcc_assert (from_macro_expansion_at (loc_a));
gcc_assert (from_macro_expansion_at (loc_b));
const line_map_macro *map_a = get_outermost_macro_expansion (loc_a);
const line_map_macro *map_b = get_outermost_macro_expansion (loc_b);
if (map_a->macro == map_b->macro)
if (!cpp_fun_like_macro_p (map_a->macro))
return true;
return false;
}
/* Warn if a self-comparison always evaluates to true or false. LOC
is the location of the comparison with code CODE, LHS and RHS are
operands of the comparison. */
void
warn_tautological_cmp (const op_location_t &loc, enum tree_code code,
tree lhs, tree rhs)
{
if (TREE_CODE_CLASS (code) != tcc_comparison)
return;
/* Don't warn for various macro expansions. */
if (from_macro_expansion_at (loc))
return;
bool lhs_in_macro = from_macro_expansion_at (EXPR_LOCATION (lhs));
bool rhs_in_macro = from_macro_expansion_at (EXPR_LOCATION (rhs));
if (lhs_in_macro || rhs_in_macro)
{
/* Don't warn if exactly one is from a macro. */
if (!(lhs_in_macro && rhs_in_macro))
return;
/* If both are in a macro, only warn if they're spelled the same. */
if (!spelled_the_same_p (EXPR_LOCATION (lhs), EXPR_LOCATION (rhs)))
return;
}
warn_tautological_bitwise_comparison (loc, code, lhs, rhs);
/* We do not warn for constants because they are typical of macro
expansions that test for features, sizeof, and similar. */
if (CONSTANT_CLASS_P (fold_for_warn (lhs))
|| CONSTANT_CLASS_P (fold_for_warn (rhs)))
return;
/* Don't warn for e.g.
HOST_WIDE_INT n;
...
if (n == (long) n) ...
*/
if ((CONVERT_EXPR_P (lhs) || TREE_CODE (lhs) == NON_LVALUE_EXPR)
|| (CONVERT_EXPR_P (rhs) || TREE_CODE (rhs) == NON_LVALUE_EXPR))
return;
/* Don't warn if either LHS or RHS has an IEEE floating-point type.
It could be a NaN, and NaN never compares equal to anything, even
itself. */
if (FLOAT_TYPE_P (TREE_TYPE (lhs)) || FLOAT_TYPE_P (TREE_TYPE (rhs)))
return;
if (operand_equal_p (lhs, rhs, 0))
{
/* Don't warn about array references with constant indices;
these are likely to come from a macro. */
if (walk_tree_without_duplicates (&lhs, find_array_ref_with_const_idx_r,
NULL))
return;
const bool always_true = (code == EQ_EXPR || code == LE_EXPR
|| code == GE_EXPR || code == UNLE_EXPR
|| code == UNGE_EXPR || code == UNEQ_EXPR);
binary_op_rich_location richloc (loc, lhs, rhs, false);
if (always_true)
warning_at (&richloc, OPT_Wtautological_compare,
"self-comparison always evaluates to true");
else
warning_at (&richloc, OPT_Wtautological_compare,
"self-comparison always evaluates to false");
}
}
/* Return true iff EXPR only contains boolean operands, or comparisons. */
static bool
expr_has_boolean_operands_p (tree expr)
{
STRIP_NOPS (expr);
if (CONVERT_EXPR_P (expr))
return bool_promoted_to_int_p (expr);
else if (UNARY_CLASS_P (expr))
return expr_has_boolean_operands_p (TREE_OPERAND (expr, 0));
else if (BINARY_CLASS_P (expr))
return (expr_has_boolean_operands_p (TREE_OPERAND (expr, 0))
&& expr_has_boolean_operands_p (TREE_OPERAND (expr, 1)));
else if (COMPARISON_CLASS_P (expr))
return true;
else
return false;
}
/* Warn about logical not used on the left hand side operand of a comparison.
This function assumes that the LHS is inside of TRUTH_NOT_EXPR.
Do not warn if RHS is of a boolean type, a logical operator, or
a comparison. */
void
warn_logical_not_parentheses (location_t location, enum tree_code code,
tree lhs, tree rhs)
{
if (TREE_CODE_CLASS (code) != tcc_comparison
|| TREE_TYPE (rhs) == NULL_TREE
|| TREE_CODE (TREE_TYPE (rhs)) == BOOLEAN_TYPE
|| truth_value_p (TREE_CODE (rhs)))
return;
/* Don't warn for expression like !x == ~(bool1 | bool2). */
if (expr_has_boolean_operands_p (rhs))
return;
/* Don't warn for !x == 0 or !y != 0, those are equivalent to
!(x == 0) or !(y != 0). */
if ((code == EQ_EXPR || code == NE_EXPR)
&& integer_zerop (rhs))
return;
auto_diagnostic_group d;
if (warning_at (location, OPT_Wlogical_not_parentheses,
"logical not is only applied to the left hand side of "
"comparison")
&& EXPR_HAS_LOCATION (lhs))
{
location_t lhs_loc = EXPR_LOCATION (lhs);
rich_location richloc (line_table, lhs_loc);
richloc.add_fixit_insert_before (lhs_loc, "(");
richloc.add_fixit_insert_after (lhs_loc, ")");
inform (&richloc, "add parentheses around left hand side "
"expression to silence this warning");
}
}
/* Warn if EXP contains any computations whose results are not used.
Return true if a warning is printed; false otherwise. LOCUS is the
(potential) location of the expression. */
bool
warn_if_unused_value (const_tree exp, location_t locus, bool quiet)
{
restart:
if (TREE_USED (exp) || warning_suppressed_p (exp, OPT_Wunused_value))
return false;
/* Don't warn about void constructs. This includes casting to void,
void function calls, and statement expressions with a final cast
to void. */
if (VOID_TYPE_P (TREE_TYPE (exp)))
return false;
if (EXPR_HAS_LOCATION (exp))
locus = EXPR_LOCATION (exp);
switch (TREE_CODE (exp))
{
case PREINCREMENT_EXPR:
case POSTINCREMENT_EXPR:
case PREDECREMENT_EXPR:
case POSTDECREMENT_EXPR:
case MODIFY_EXPR:
case INIT_EXPR:
case TARGET_EXPR:
case CALL_EXPR:
case TRY_CATCH_EXPR:
case EXIT_EXPR:
case VA_ARG_EXPR:
return false;
case BIND_EXPR:
/* For a binding, warn if no side effect within it. */
exp = BIND_EXPR_BODY (exp);
goto restart;
case SAVE_EXPR:
case NON_LVALUE_EXPR:
case NOP_EXPR:
exp = TREE_OPERAND (exp, 0);
goto restart;
case TRUTH_ORIF_EXPR:
case TRUTH_ANDIF_EXPR:
/* In && or ||, warn if 2nd operand has no side effect. */
exp = TREE_OPERAND (exp, 1);
goto restart;
case COMPOUND_EXPR:
if (warn_if_unused_value (TREE_OPERAND (exp, 0), locus, quiet))
return true;
/* Let people do `(foo (), 0)' without a warning. */
if (TREE_CONSTANT (TREE_OPERAND (exp, 1)))
return false;
exp = TREE_OPERAND (exp, 1);
goto restart;
case COND_EXPR:
/* If this is an expression with side effects, don't warn; this
case commonly appears in macro expansions. */
if (TREE_SIDE_EFFECTS (exp))
return false;
goto warn;
case COMPLEX_EXPR:
/* Warn only if both operands are unused. */
if (warn_if_unused_value (TREE_OPERAND (exp, 0), locus, true)
&& warn_if_unused_value (TREE_OPERAND (exp, 1), locus, true))
goto warn;
return false;
case INDIRECT_REF:
/* Don't warn about automatic dereferencing of references, since
the user cannot control it. */
if (TREE_CODE (TREE_TYPE (TREE_OPERAND (exp, 0))) == REFERENCE_TYPE)
{
exp = TREE_OPERAND (exp, 0);
goto restart;
}
/* Fall through. */
default:
/* Referencing a volatile value is a side effect, so don't warn. */
if ((DECL_P (exp) || REFERENCE_CLASS_P (exp))
&& TREE_THIS_VOLATILE (exp))
return false;
/* If this is an expression which has no operands, there is no value
to be unused. There are no such language-independent codes,
but front ends may define such. */
if (EXPRESSION_CLASS_P (exp) && TREE_OPERAND_LENGTH (exp) == 0)
return false;
warn:
if (quiet)
return true;
return warning_at (locus, OPT_Wunused_value, "value computed is not used");
}
}
/* Print a warning about casts that might indicate violation of strict
aliasing rules if -Wstrict-aliasing is used and strict aliasing
mode is in effect. LOC is the location of the expression being
cast, EXPR might be from inside it. TYPE is the type we're casting
to. */
bool
strict_aliasing_warning (location_t loc, tree type, tree expr)
{
if (loc == UNKNOWN_LOCATION)
loc = input_location;
/* Strip pointer conversion chains and get to the correct original type. */
STRIP_NOPS (expr);
tree otype = TREE_TYPE (expr);
if (!(flag_strict_aliasing
&& POINTER_TYPE_P (type)
&& POINTER_TYPE_P (otype)
&& !VOID_TYPE_P (TREE_TYPE (type)))
/* If the type we are casting to is a ref-all pointer
dereferencing it is always valid. */
|| TYPE_REF_CAN_ALIAS_ALL (type))
return false;
if ((warn_strict_aliasing > 1) && TREE_CODE (expr) == ADDR_EXPR
&& (DECL_P (TREE_OPERAND (expr, 0))
|| handled_component_p (TREE_OPERAND (expr, 0))))
{
/* Casting the address of an object to non void pointer. Warn
if the cast breaks type based aliasing. */
if (!COMPLETE_TYPE_P (TREE_TYPE (type)) && warn_strict_aliasing == 2)
{
warning_at (loc, OPT_Wstrict_aliasing,
"type-punning to incomplete type "
"might break strict-aliasing rules");
return true;
}
else
{
/* warn_strict_aliasing >= 3. This includes the default (3).
Only warn if the cast is dereferenced immediately. */
alias_set_type set1
= get_alias_set (TREE_TYPE (TREE_OPERAND (expr, 0)));
alias_set_type set2 = get_alias_set (TREE_TYPE (type));
if (set2 != 0
&& set1 != set2
&& !alias_set_subset_of (set2, set1)
&& !alias_sets_conflict_p (set1, set2))
{
warning_at (loc, OPT_Wstrict_aliasing,
"dereferencing type-punned "
"pointer will break strict-aliasing rules");
return true;
}
else if (warn_strict_aliasing == 2
&& !alias_sets_must_conflict_p (set1, set2))
{
warning_at (loc, OPT_Wstrict_aliasing,
"dereferencing type-punned "
"pointer might break strict-aliasing rules");
return true;
}
}
}
else if ((warn_strict_aliasing == 1) && !VOID_TYPE_P (TREE_TYPE (otype)))
{
/* At this level, warn for any conversions, even if an address is
not taken in the same statement. This will likely produce many
false positives, but could be useful to pinpoint problems that
are not revealed at higher levels. */
alias_set_type set1 = get_alias_set (TREE_TYPE (otype));
alias_set_type set2 = get_alias_set (TREE_TYPE (type));
if (!COMPLETE_TYPE_P (TREE_TYPE (type))
|| !alias_sets_must_conflict_p (set1, set2))
{
warning_at (loc, OPT_Wstrict_aliasing,
"dereferencing type-punned "
"pointer might break strict-aliasing rules");
return true;
}
}
return false;
}
/* Warn about memset (&a, 0, sizeof (&a)); and similar mistakes with
sizeof as last operand of certain builtins. */
void
sizeof_pointer_memaccess_warning (location_t *sizeof_arg_loc, tree callee,
vec<tree, va_gc> *params, tree *sizeof_arg,
bool (*comp_types) (tree, tree))
{
tree type, dest = NULL_TREE, src = NULL_TREE, tem;
bool strop = false, cmp = false;
unsigned int idx = ~0;
location_t loc;
if (TREE_CODE (callee) != FUNCTION_DECL
|| !fndecl_built_in_p (callee, BUILT_IN_NORMAL)
|| vec_safe_length (params) <= 1)
return;
enum built_in_function fncode = DECL_FUNCTION_CODE (callee);
switch (fncode)
{
case BUILT_IN_STRNCMP:
case BUILT_IN_STRNCASECMP:
cmp = true;
/* FALLTHRU */
case BUILT_IN_STRNCPY:
case BUILT_IN_STRNCPY_CHK:
case BUILT_IN_STRNCAT:
case BUILT_IN_STRNCAT_CHK:
case BUILT_IN_STPNCPY:
case BUILT_IN_STPNCPY_CHK:
strop = true;
/* FALLTHRU */
case BUILT_IN_MEMCPY:
case BUILT_IN_MEMCPY_CHK:
case BUILT_IN_MEMMOVE:
case BUILT_IN_MEMMOVE_CHK:
if (params->length () < 3)
return;
src = (*params)[1];
dest = (*params)[0];
idx = 2;
break;
case BUILT_IN_BCOPY:
if (params->length () < 3)
return;
src = (*params)[0];
dest = (*params)[1];
idx = 2;
break;
case BUILT_IN_MEMCMP:
case BUILT_IN_BCMP:
if (params->length () < 3)
return;
src = (*params)[1];
dest = (*params)[0];
idx = 2;
cmp = true;
break;
case BUILT_IN_MEMSET:
case BUILT_IN_MEMSET_CHK:
if (params->length () < 3)
return;
dest = (*params)[0];
idx = 2;
break;
case BUILT_IN_BZERO:
dest = (*params)[0];
idx = 1;
break;
case BUILT_IN_STRNDUP:
src = (*params)[0];
strop = true;
idx = 1;
break;
case BUILT_IN_MEMCHR:
if (params->length () < 3)
return;
src = (*params)[0];
idx = 2;
break;
case BUILT_IN_SNPRINTF:
case BUILT_IN_SNPRINTF_CHK:
case BUILT_IN_VSNPRINTF:
case BUILT_IN_VSNPRINTF_CHK:
dest = (*params)[0];
idx = 1;
strop = true;
break;
default:
break;
}
if (idx >= 3)
return;
/* Use error_operand_p to detect non-error arguments with an error
type that the C++ front-end constructs. */
if (error_operand_p (src)
|| error_operand_p (dest)
|| !sizeof_arg[idx]
|| error_operand_p (sizeof_arg[idx]))
return;
type = TYPE_P (sizeof_arg[idx])
? sizeof_arg[idx] : TREE_TYPE (sizeof_arg[idx]);
if (!POINTER_TYPE_P (type))
{
/* The argument type may be an array. Diagnose bounded string
copy functions that specify the bound in terms of the source
argument rather than the destination unless they are equal
to one another. Handle constant sizes and also try to handle
sizeof expressions involving VLAs. */
if (strop && !cmp && fncode != BUILT_IN_STRNDUP && src)
{
tem = tree_strip_nop_conversions (src);
if (TREE_CODE (tem) == ADDR_EXPR)
tem = TREE_OPERAND (tem, 0);
/* Avoid diagnosing sizeof SRC when SRC is declared with
attribute nonstring. */
tree dummy;
if (get_attr_nonstring_decl (tem, &dummy))
return;
tree d = tree_strip_nop_conversions (dest);
if (TREE_CODE (d) == ADDR_EXPR)
d = TREE_OPERAND (d, 0);
tree dstsz = TYPE_SIZE_UNIT (TREE_TYPE (d));
tree srcsz = TYPE_SIZE_UNIT (TREE_TYPE (tem));
if ((!dstsz
|| !srcsz
|| !operand_equal_p (dstsz, srcsz, OEP_LEXICOGRAPHIC))
&& operand_equal_p (tem, sizeof_arg[idx], OEP_ADDRESS_OF))
warning_at (sizeof_arg_loc[idx], OPT_Wsizeof_pointer_memaccess,
"argument to %<sizeof%> in %qD call is the same "
"expression as the source; did you mean to use "
"the size of the destination?",
callee);
}
return;
}
if (dest
&& (tem = tree_strip_nop_conversions (dest))
&& POINTER_TYPE_P (TREE_TYPE (tem))
&& comp_types (TREE_TYPE (TREE_TYPE (tem)), type))
return;
if (src
&& (tem = tree_strip_nop_conversions (src))
&& POINTER_TYPE_P (TREE_TYPE (tem))
&& comp_types (TREE_TYPE (TREE_TYPE (tem)), type))
return;
loc = sizeof_arg_loc[idx];
if (dest && !cmp)
{
if (!TYPE_P (sizeof_arg[idx])
&& operand_equal_p (dest, sizeof_arg[idx], 0)
&& comp_types (TREE_TYPE (dest), type))
{
if (TREE_CODE (sizeof_arg[idx]) == ADDR_EXPR && !strop)
warning_at (loc, OPT_Wsizeof_pointer_memaccess,
"argument to %<sizeof%> in %qD call is the same "
"expression as the destination; did you mean to "
"remove the addressof?", callee);
else if ((TYPE_PRECISION (TREE_TYPE (type))
== TYPE_PRECISION (char_type_node))
|| strop)
warning_at (loc, OPT_Wsizeof_pointer_memaccess,
"argument to %<sizeof%> in %qD call is the same "
"expression as the destination; did you mean to "
"provide an explicit length?", callee);
else
warning_at (loc, OPT_Wsizeof_pointer_memaccess,
"argument to %<sizeof%> in %qD call is the same "
"expression as the destination; did you mean to "
"dereference it?", callee);
return;
}
if (POINTER_TYPE_P (TREE_TYPE (dest))
&& !strop
&& comp_types (TREE_TYPE (dest), type)
&& !VOID_TYPE_P (TREE_TYPE (type)))
{
warning_at (loc, OPT_Wsizeof_pointer_memaccess,
"argument to %<sizeof%> in %qD call is the same "
"pointer type %qT as the destination; expected %qT "
"or an explicit length", callee, TREE_TYPE (dest),
TREE_TYPE (TREE_TYPE (dest)));
return;
}
}
if (src && !cmp)
{
if (!TYPE_P (sizeof_arg[idx])
&& operand_equal_p (src, sizeof_arg[idx], 0)
&& comp_types (TREE_TYPE (src), type))
{
if (TREE_CODE (sizeof_arg[idx]) == ADDR_EXPR && !strop)
warning_at (loc, OPT_Wsizeof_pointer_memaccess,
"argument to %<sizeof%> in %qD call is the same "
"expression as the source; did you mean to "
"remove the addressof?", callee);
else if ((TYPE_PRECISION (TREE_TYPE (type))
== TYPE_PRECISION (char_type_node))
|| strop)
warning_at (loc, OPT_Wsizeof_pointer_memaccess,
"argument to %<sizeof%> in %qD call is the same "
"expression as the source; did you mean to "
"provide an explicit length?", callee);
else
warning_at (loc, OPT_Wsizeof_pointer_memaccess,
"argument to %<sizeof%> in %qD call is the same "
"expression as the source; did you mean to "
"dereference it?", callee);
return;
}
if (POINTER_TYPE_P (TREE_TYPE (src))
&& !strop
&& comp_types (TREE_TYPE (src), type)
&& !VOID_TYPE_P (TREE_TYPE (type)))
{
warning_at (loc, OPT_Wsizeof_pointer_memaccess,
"argument to %<sizeof%> in %qD call is the same "
"pointer type %qT as the source; expected %qT "
"or an explicit length", callee, TREE_TYPE (src),
TREE_TYPE (TREE_TYPE (src)));
return;
}
}
if (dest)
{
if (!TYPE_P (sizeof_arg[idx])
&& operand_equal_p (dest, sizeof_arg[idx], 0)
&& comp_types (TREE_TYPE (dest), type))
{
if (TREE_CODE (sizeof_arg[idx]) == ADDR_EXPR && !strop)
warning_at (loc, OPT_Wsizeof_pointer_memaccess,
"argument to %<sizeof%> in %qD call is the same "
"expression as the first source; did you mean to "
"remove the addressof?", callee);
else if ((TYPE_PRECISION (TREE_TYPE (type))
== TYPE_PRECISION (char_type_node))
|| strop)
warning_at (loc, OPT_Wsizeof_pointer_memaccess,
"argument to %<sizeof%> in %qD call is the same "
"expression as the first source; did you mean to "
"provide an explicit length?", callee);
else
warning_at (loc, OPT_Wsizeof_pointer_memaccess,
"argument to %<sizeof%> in %qD call is the same "
"expression as the first source; did you mean to "
"dereference it?", callee);
return;
}
if (POINTER_TYPE_P (TREE_TYPE (dest))
&& !strop
&& comp_types (TREE_TYPE (dest), type)
&& !VOID_TYPE_P (TREE_TYPE (type)))
{
warning_at (loc, OPT_Wsizeof_pointer_memaccess,
"argument to %<sizeof%> in %qD call is the same "
"pointer type %qT as the first source; expected %qT "
"or an explicit length", callee, TREE_TYPE (dest),
TREE_TYPE (TREE_TYPE (dest)));
return;
}
}
if (src)
{
if (!TYPE_P (sizeof_arg[idx])
&& operand_equal_p (src, sizeof_arg[idx], 0)
&& comp_types (TREE_TYPE (src), type))
{
if (TREE_CODE (sizeof_arg[idx]) == ADDR_EXPR && !strop)
warning_at (loc, OPT_Wsizeof_pointer_memaccess,
"argument to %<sizeof%> in %qD call is the same "
"expression as the second source; did you mean to "
"remove the addressof?", callee);
else if ((TYPE_PRECISION (TREE_TYPE (type))
== TYPE_PRECISION (char_type_node))
|| strop)
warning_at (loc, OPT_Wsizeof_pointer_memaccess,
"argument to %<sizeof%> in %qD call is the same "
"expression as the second source; did you mean to "
"provide an explicit length?", callee);
else
warning_at (loc, OPT_Wsizeof_pointer_memaccess,
"argument to %<sizeof%> in %qD call is the same "
"expression as the second source; did you mean to "
"dereference it?", callee);
return;
}
if (POINTER_TYPE_P (TREE_TYPE (src))
&& !strop
&& comp_types (TREE_TYPE (src), type)
&& !VOID_TYPE_P (TREE_TYPE (type)))
{
warning_at (loc, OPT_Wsizeof_pointer_memaccess,
"argument to %<sizeof%> in %qD call is the same "
"pointer type %qT as the second source; expected %qT "
"or an explicit length", callee, TREE_TYPE (src),
TREE_TYPE (TREE_TYPE (src)));
return;
}
}
}
/* Warn for unlikely, improbable, or stupid DECL declarations
of `main'. */
void
check_main_parameter_types (tree decl)
{
function_args_iterator iter;
tree type;
int argct = 0;
FOREACH_FUNCTION_ARGS (TREE_TYPE (decl), type, iter)
{
/* XXX void_type_node belies the abstraction. */
if (type == void_type_node || type == error_mark_node)
break;
tree t = type;
if (TYPE_ATOMIC (t))
pedwarn (input_location, OPT_Wmain,
"%<_Atomic%>-qualified parameter type %qT of %q+D",
type, decl);
while (POINTER_TYPE_P (t))
{
t = TREE_TYPE (t);
if (TYPE_ATOMIC (t))
pedwarn (input_location, OPT_Wmain,
"%<_Atomic%>-qualified parameter type %qT of %q+D",
type, decl);
}
++argct;
switch (argct)
{
case 1:
if (TYPE_MAIN_VARIANT (type) != integer_type_node)
pedwarn (input_location, OPT_Wmain,
"first argument of %q+D should be %<int%>", decl);
break;
case 2:
if (TREE_CODE (type) != POINTER_TYPE
|| TREE_CODE (TREE_TYPE (type)) != POINTER_TYPE
|| (TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (type)))
!= char_type_node))
pedwarn (input_location, OPT_Wmain,
"second argument of %q+D should be %<char **%>", decl);
break;
case 3:
if (TREE_CODE (type) != POINTER_TYPE
|| TREE_CODE (TREE_TYPE (type)) != POINTER_TYPE
|| (TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (type)))
!= char_type_node))
pedwarn (input_location, OPT_Wmain,
"third argument of %q+D should probably be "
"%<char **%>", decl);
break;
}
}
/* It is intentional that this message does not mention the third
argument because it's only mentioned in an appendix of the
standard. */
if (argct > 0 && (argct < 2 || argct > 3))
pedwarn (input_location, OPT_Wmain,
"%q+D takes only zero or two arguments", decl);
if (stdarg_p (TREE_TYPE (decl)))
pedwarn (input_location, OPT_Wmain,
"%q+D declared as variadic function", decl);
}
/* Warns and returns true if the conversion of EXPR to TYPE may alter a value.
This is a helper function for warnings_for_convert_and_check. */
static bool
conversion_warning (location_t loc, tree type, tree expr, tree result)
{
tree expr_type = TREE_TYPE (expr);
enum conversion_safety conversion_kind;
int arith_ops = 0;
if (!warn_conversion && !warn_sign_conversion && !warn_float_conversion)
return false;
/* This may happen, because for LHS op= RHS we preevaluate
RHS and create C_MAYBE_CONST_EXPR <SAVE_EXPR <RHS>>, which
means we could no longer see the code of the EXPR. */
if (TREE_CODE (expr) == C_MAYBE_CONST_EXPR)
expr = C_MAYBE_CONST_EXPR_EXPR (expr);
if (TREE_CODE (expr) == SAVE_EXPR)
expr = TREE_OPERAND (expr, 0);
switch (TREE_CODE (expr))
{
case EQ_EXPR:
case NE_EXPR:
case LE_EXPR:
case GE_EXPR:
case LT_EXPR:
case GT_EXPR:
case TRUTH_ANDIF_EXPR:
case TRUTH_ORIF_EXPR:
case TRUTH_AND_EXPR:
case TRUTH_OR_EXPR:
case TRUTH_XOR_EXPR:
case TRUTH_NOT_EXPR:
/* Conversion from boolean to a signed:1 bit-field (which only
can hold the values 0 and -1) doesn't lose information - but
it does change the value. */
if (TYPE_PRECISION (type) == 1 && !TYPE_UNSIGNED (type))
warning_at (loc, OPT_Wconversion,
"conversion to %qT from boolean expression", type);
return true;
case REAL_CST:
case INTEGER_CST:
case COMPLEX_CST:
{
conversion_kind = unsafe_conversion_p (type, expr, result, true);
int warnopt;
if (conversion_kind == UNSAFE_REAL)
warnopt = OPT_Wfloat_conversion;
else if (conversion_kind)
warnopt = OPT_Wconversion;
else
break;
if (conversion_kind == UNSAFE_SIGN)
{
bool cstresult
= (result
&& TREE_CODE_CLASS (TREE_CODE (result)) == tcc_constant);
if (TYPE_UNSIGNED (type))
{
if (cstresult)
warning_at (loc, OPT_Wsign_conversion,
"unsigned conversion from %qT to %qT "
"changes value from %qE to %qE",
expr_type, type, expr, result);
else
warning_at (loc, OPT_Wsign_conversion,
"unsigned conversion from %qT to %qT "
"changes the value of %qE",
expr_type, type, expr);
}
else
{
if (cstresult)
warning_at (loc, OPT_Wsign_conversion,
"signed conversion from %qT to %qT changes "
"value from %qE to %qE",
expr_type, type, expr, result);
else
warning_at (loc, OPT_Wsign_conversion,
"signed conversion from %qT to %qT changes "
"the value of %qE",
expr_type, type, expr);
}
}
else if (TREE_CODE_CLASS (TREE_CODE (result)) == tcc_constant)
warning_at (loc, warnopt,
"conversion from %qT to %qT changes value from %qE to %qE",
expr_type, type, expr, result);
else
warning_at (loc, warnopt,
"conversion from %qT to %qT changes the value of %qE",
expr_type, type, expr);
return true;
}
case PLUS_EXPR:
case MINUS_EXPR:
case MULT_EXPR:
case MAX_EXPR:
case MIN_EXPR:
case TRUNC_MOD_EXPR:
case FLOOR_MOD_EXPR:
case TRUNC_DIV_EXPR:
case FLOOR_DIV_EXPR:
case CEIL_DIV_EXPR:
case EXACT_DIV_EXPR:
case RDIV_EXPR:
arith_ops = 2;
goto default_;
case PREDECREMENT_EXPR:
case PREINCREMENT_EXPR:
case POSTDECREMENT_EXPR:
case POSTINCREMENT_EXPR:
case LSHIFT_EXPR:
case RSHIFT_EXPR:
case FIX_TRUNC_EXPR:
case NON_LVALUE_EXPR:
case NEGATE_EXPR:
case BIT_NOT_EXPR:
arith_ops = 1;
goto default_;
case COND_EXPR:
{
/* In case of COND_EXPR, we do not care about the type of
COND_EXPR, only about the conversion of each operand. */
tree op1 = TREE_OPERAND (expr, 1);
tree op2 = TREE_OPERAND (expr, 2);
return (conversion_warning (loc, type, op1, result)
|| conversion_warning (loc, type, op2, result));
}
default_:
default:
conversion_kind = unsafe_conversion_p (type, expr, result, true);
{
int warnopt;
if (conversion_kind == UNSAFE_REAL)
warnopt = OPT_Wfloat_conversion;
else if (conversion_kind == UNSAFE_SIGN)
warnopt = OPT_Wsign_conversion;
else if (conversion_kind)
warnopt = OPT_Wconversion;
else
break;
if (arith_ops
&& global_dc->option_enabled (warnopt,
global_dc->lang_mask,
global_dc->option_state))
{
for (int i = 0; i < arith_ops; ++i)
{
tree op = TREE_OPERAND (expr, i);
/* Avoid -Wsign-conversion for (unsigned)(x + (-1)). */
if (TREE_CODE (expr) == PLUS_EXPR && i == 1
&& INTEGRAL_TYPE_P (type) && TYPE_UNSIGNED (type)
&& TREE_CODE (op) == INTEGER_CST
&& tree_int_cst_sgn (op) < 0)
op = fold_build1 (NEGATE_EXPR, TREE_TYPE (op), op);
tree opr = convert (type, op);
if (unsafe_conversion_p (type, op, opr, true))
goto op_unsafe;
}
/* The operands seem safe, we might still want to warn if
-Warith-conversion. */
warnopt = OPT_Warith_conversion;
op_unsafe:;
}
if (conversion_kind == UNSAFE_SIGN)
warning_at (loc, warnopt, "conversion to %qT from %qT "
"may change the sign of the result",
type, expr_type);
else if (conversion_kind == UNSAFE_IMAGINARY)
warning_at (loc, warnopt,
"conversion from %qT to %qT discards imaginary component",
expr_type, type);
else
warning_at (loc, warnopt,
"conversion from %qT to %qT may change value",
expr_type, type);
return true;
}
}
return false;
}
/* Produce warnings after a conversion. RESULT is the result of
converting EXPR to TYPE. This is a helper function for
convert_and_check and cp_convert_and_check. */
void
warnings_for_convert_and_check (location_t loc, tree type, tree expr,
tree result)
{
loc = expansion_point_location_if_in_system_header (loc);
while (TREE_CODE (expr) == COMPOUND_EXPR)
expr = TREE_OPERAND (expr, 1);
while (TREE_CODE (result) == COMPOUND_EXPR)
result = TREE_OPERAND (result, 1);
bool cst = TREE_CODE_CLASS (TREE_CODE (result)) == tcc_constant;
tree exprtype = TREE_TYPE (expr);
if (TREE_CODE (expr) == INTEGER_CST
&& (TREE_CODE (type) == INTEGER_TYPE
|| TREE_CODE (type) == ENUMERAL_TYPE)
&& !int_fits_type_p (expr, type))
{
/* Do not diagnose overflow in a constant expression merely
because a conversion overflowed. */
if (TREE_OVERFLOW (result))
TREE_OVERFLOW (result) = TREE_OVERFLOW (expr);
if (TYPE_UNSIGNED (type))
{
/* This detects cases like converting -129 or 256 to
unsigned char. */
if (!int_fits_type_p (expr, c_common_signed_type (type)))
{
if (cst)
warning_at (loc, OPT_Woverflow,
(TYPE_UNSIGNED (exprtype)
? G_("conversion from %qT to %qT "
"changes value from %qE to %qE")
: G_("unsigned conversion from %qT to %qT "
"changes value from %qE to %qE")),
exprtype, type, expr, result);
else
warning_at (loc, OPT_Woverflow,
(TYPE_UNSIGNED (exprtype)
? G_("conversion from %qT to %qT "
"changes the value of %qE")
: G_("unsigned conversion from %qT to %qT "
"changes the value of %qE")),
exprtype, type, expr);
}
else
conversion_warning (loc, type, expr, result);
}
else if (!int_fits_type_p (expr, c_common_unsigned_type (type)))
{
if (cst)
warning_at (loc, OPT_Woverflow,
"overflow in conversion from %qT to %qT "
"changes value from %qE to %qE",
exprtype, type, expr, result);
else
warning_at (loc, OPT_Woverflow,
"overflow in conversion from %qT to %qT "
"changes the value of %qE",
exprtype, type, expr);
}
/* No warning for converting 0x80000000 to int. */
else if (pedantic
&& (TREE_CODE (exprtype) != INTEGER_TYPE
|| TYPE_PRECISION (exprtype)
!= TYPE_PRECISION (type)))
{
if (cst)
warning_at (loc, OPT_Woverflow,
"overflow in conversion from %qT to %qT "
"changes value from %qE to %qE",
exprtype, type, expr, result);
else
warning_at (loc, OPT_Woverflow,
"overflow in conversion from %qT to %qT "
"changes the value of %qE",
exprtype, type, expr);
}
else
conversion_warning (loc, type, expr, result);
}
else if ((TREE_CODE (result) == INTEGER_CST
|| TREE_CODE (result) == FIXED_CST) && TREE_OVERFLOW (result))
{
if (cst)
warning_at (loc, OPT_Woverflow,
"overflow in conversion from %qT to %qT "
"changes value from %qE to %qE",
exprtype, type, expr, result);
else
warning_at (loc, OPT_Woverflow,
"overflow in conversion from %qT to %qT "
"changes the value of %qE",
exprtype, type, expr);
}
else
conversion_warning (loc, type, expr, result);
}
/* Subroutines of c_do_switch_warnings, called via splay_tree_foreach.
Used to verify that case values match up with enumerator values. */
static void
match_case_to_enum_1 (tree key, tree type, tree label)
{
/* Avoid warning about enums that have no enumerators. */
if (TYPE_VALUES (type) == NULL_TREE)
return;
char buf[WIDE_INT_PRINT_BUFFER_SIZE];
if (tree_fits_uhwi_p (key))
print_dec (wi::to_wide (key), buf, UNSIGNED);
else if (tree_fits_shwi_p (key))
print_dec (wi::to_wide (key), buf, SIGNED);
else
print_hex (wi::to_wide (key), buf);
if (TYPE_NAME (type) == NULL_TREE)
warning_at (DECL_SOURCE_LOCATION (CASE_LABEL (label)),
warn_switch ? OPT_Wswitch : OPT_Wswitch_enum,
"case value %qs not in enumerated type",
buf);
else
warning_at (DECL_SOURCE_LOCATION (CASE_LABEL (label)),
warn_switch ? OPT_Wswitch : OPT_Wswitch_enum,
"case value %qs not in enumerated type %qT",
buf, type);
}
/* Subroutine of c_do_switch_warnings, called via splay_tree_foreach.
Used to verify that case values match up with enumerator values. */
static int
match_case_to_enum (splay_tree_node node, void *data)
{
tree label = (tree) node->value;
tree type = (tree) data;
/* Skip default case. */
if (!CASE_LOW (label))
return 0;
/* If CASE_LOW_SEEN is not set, that means CASE_LOW did not appear
when we did our enum->case scan. Reset our scratch bit after. */
if (!CASE_LOW_SEEN (label))
match_case_to_enum_1 (CASE_LOW (label), type, label);
else
CASE_LOW_SEEN (label) = 0;
/* If CASE_HIGH is non-null, we have a range. If CASE_HIGH_SEEN is
not set, that means that CASE_HIGH did not appear when we did our
enum->case scan. Reset our scratch bit after. */
if (CASE_HIGH (label))
{
if (!CASE_HIGH_SEEN (label))
match_case_to_enum_1 (CASE_HIGH (label), type, label);
else
CASE_HIGH_SEEN (label) = 0;
}
return 0;
}
/* Handle -Wswitch*. Called from the front end after parsing the
switch construct. */
/* ??? Should probably be somewhere generic, since other languages
besides C and C++ would want this. At the moment, however, C/C++
are the only tree-ssa languages that support enumerations at all,
so the point is moot. */
void
c_do_switch_warnings (splay_tree cases, location_t switch_location,
tree type, tree cond, bool bool_cond_p)
{
splay_tree_node default_node;
splay_tree_node node;
tree chain;
bool outside_range_p = false;
if (type != error_mark_node
&& type != TREE_TYPE (cond)
&& INTEGRAL_TYPE_P (type)
&& INTEGRAL_TYPE_P (TREE_TYPE (cond))
&& (!tree_int_cst_equal (TYPE_MIN_VALUE (type),
TYPE_MIN_VALUE (TREE_TYPE (cond)))
|| !tree_int_cst_equal (TYPE_MAX_VALUE (type),
TYPE_MAX_VALUE (TREE_TYPE (cond)))))
{
tree min_value = TYPE_MIN_VALUE (type);
tree max_value = TYPE_MAX_VALUE (type);
node = splay_tree_predecessor (cases, (splay_tree_key) min_value);
if (node && node->key)
{
outside_range_p = true;
/* There is at least one case smaller than TYPE's minimum value.
NODE itself could be still a range overlapping the valid values,
but any predecessors thereof except the default case will be
completely outside of range. */
if (CASE_HIGH ((tree) node->value)
&& tree_int_cst_compare (CASE_HIGH ((tree) node->value),
min_value) >= 0)
{
location_t loc = EXPR_LOCATION ((tree) node->value);
warning_at (loc, OPT_Wswitch_outside_range,
"lower value in case label range less than minimum"
" value for type");
CASE_LOW ((tree) node->value) = convert (TREE_TYPE (cond),
min_value);
node->key = (splay_tree_key) CASE_LOW ((tree) node->value);
}
/* All the following ones are completely outside of range. */
do
{
node = splay_tree_predecessor (cases,
(splay_tree_key) min_value);
if (node == NULL || !node->key)
break;
location_t loc = EXPR_LOCATION ((tree) node->value);
warning_at (loc, OPT_Wswitch_outside_range, "case label value is"
" less than minimum value for type");
splay_tree_remove (cases, node->key);
}
while (1);
}
node = splay_tree_lookup (cases, (splay_tree_key) max_value);
if (node == NULL)
node = splay_tree_predecessor (cases, (splay_tree_key) max_value);
/* Handle a single node that might partially overlap the range. */
if (node
&& node->key
&& CASE_HIGH ((tree) node->value)
&& tree_int_cst_compare (CASE_HIGH ((tree) node->value),
max_value) > 0)
{
location_t loc = EXPR_LOCATION ((tree) node->value);
warning_at (loc, OPT_Wswitch_outside_range, "upper value in case"
" label range exceeds maximum value for type");
CASE_HIGH ((tree) node->value)
= convert (TREE_TYPE (cond), max_value);
outside_range_p = true;
}
/* And any nodes that are completely outside of the range. */
while ((node = splay_tree_successor (cases,
(splay_tree_key) max_value))
!= NULL)
{
location_t loc = EXPR_LOCATION ((tree) node->value);
warning_at (loc, OPT_Wswitch_outside_range,
"case label value exceeds maximum value for type");
splay_tree_remove (cases, node->key);
outside_range_p = true;
}
}
if (!warn_switch && !warn_switch_enum && !warn_switch_default
&& !warn_switch_bool)
return;
default_node = splay_tree_lookup (cases, (splay_tree_key) NULL);
if (!default_node)
warning_at (switch_location, OPT_Wswitch_default,
"switch missing default case");
/* There are certain cases where -Wswitch-bool warnings aren't
desirable, such as
switch (boolean)
{
case true: ...
case false: ...
}
so be careful here. */
if (warn_switch_bool && bool_cond_p)
{
splay_tree_node min_node;
/* If there's a default node, it's also the value with the minimal
key. So look at the penultimate key (if any). */
if (default_node)
min_node = splay_tree_successor (cases, (splay_tree_key) NULL);
else
min_node = splay_tree_min (cases);
tree min = min_node ? (tree) min_node->key : NULL_TREE;
splay_tree_node max_node = splay_tree_max (cases);
/* This might be a case range, so look at the value with the
maximal key and then check CASE_HIGH. */
tree max = max_node ? (tree) max_node->value : NULL_TREE;
if (max)
max = CASE_HIGH (max) ? CASE_HIGH (max) : CASE_LOW (max);
/* If there's a case value > 1 or < 0, that is outside bool
range, warn. */
if (outside_range_p
|| (max && wi::gts_p (wi::to_wide (max), 1))
|| (min && wi::lts_p (wi::to_wide (min), 0))
/* And handle the
switch (boolean)
{
case true: ...
case false: ...
default: ...
}
case, where we want to warn. */
|| (default_node
&& max && wi::to_wide (max) == 1
&& min && wi::to_wide (min) == 0))
warning_at (switch_location, OPT_Wswitch_bool,
"switch condition has boolean value");
}
/* From here on, we only care about enumerated types. */
if (!type || TREE_CODE (type) != ENUMERAL_TYPE)
return;
/* From here on, we only care about -Wswitch and -Wswitch-enum. */
if (!warn_switch_enum && !warn_switch)
return;
/* Check the cases. Warn about case values which are not members of
the enumerated type. For -Wswitch-enum, or for -Wswitch when
there is no default case, check that exactly all enumeration
literals are covered by the cases. */
/* Clearing COND if it is not an integer constant simplifies
the tests inside the loop below. */
if (TREE_CODE (cond) != INTEGER_CST)
cond = NULL_TREE;
/* The time complexity here is O(N*lg(N)) worst case, but for the
common case of monotonically increasing enumerators, it is
O(N), since the nature of the splay tree will keep the next
element adjacent to the root at all times. */
for (chain = TYPE_VALUES (type); chain; chain = TREE_CHAIN (chain))
{
tree value = TREE_VALUE (chain);
if (TREE_CODE (value) == CONST_DECL)
value = DECL_INITIAL (value);
node = splay_tree_lookup (cases, (splay_tree_key) value);
if (node)
{
/* Mark the CASE_LOW part of the case entry as seen. */
tree label = (tree) node->value;
CASE_LOW_SEEN (label) = 1;
continue;
}
/* Even though there wasn't an exact match, there might be a
case range which includes the enumerator's value. */
node = splay_tree_predecessor (cases, (splay_tree_key) value);
if (node && CASE_HIGH ((tree) node->value))
{
tree label = (tree) node->value;
int cmp = tree_int_cst_compare (CASE_HIGH (label), value);
if (cmp >= 0)
{
/* If we match the upper bound exactly, mark the CASE_HIGH
part of the case entry as seen. */
if (cmp == 0)
CASE_HIGH_SEEN (label) = 1;
continue;
}
}
/* We've now determined that this enumerated literal isn't
handled by the case labels of the switch statement. */
/* If the switch expression is a constant, we only really care
about whether that constant is handled by the switch. */
if (cond && tree_int_cst_compare (cond, value))
continue;
/* If the enumerator is defined in a system header and uses a reserved
name, then we continue to avoid throwing a warning. */
location_t loc = DECL_SOURCE_LOCATION
(TYPE_STUB_DECL (TYPE_MAIN_VARIANT (type)));
if (in_system_header_at (loc)
&& name_reserved_for_implementation_p
(IDENTIFIER_POINTER (TREE_PURPOSE (chain))))
continue;
/* If there is a default_node, the only relevant option is
Wswitch-enum. Otherwise, if both are enabled then we prefer
to warn using -Wswitch because -Wswitch is enabled by -Wall
while -Wswitch-enum is explicit. */
warning_at (switch_location,
(default_node || !warn_switch
? OPT_Wswitch_enum
: OPT_Wswitch),
"enumeration value %qE not handled in switch",
TREE_PURPOSE (chain));
}
/* Warn if there are case expressions that don't correspond to
enumerators. This can occur since C and C++ don't enforce
type-checking of assignments to enumeration variables.
The time complexity here is now always O(N) worst case, since
we should have marked both the lower bound and upper bound of
every disjoint case label, with CASE_LOW_SEEN and CASE_HIGH_SEEN
above. This scan also resets those fields. */
splay_tree_foreach (cases, match_case_to_enum, type);
}
/* Warn for A ?: C expressions (with B omitted) where A is a boolean
expression, because B will always be true. */
void
warn_for_omitted_condop (location_t location, tree cond)
{
/* In C++ template declarations it can happen that the type is dependent
and not yet known, thus TREE_TYPE (cond) == NULL_TREE. */
if (truth_value_p (TREE_CODE (cond))
|| (TREE_TYPE (cond) != NULL_TREE
&& TREE_CODE (TREE_TYPE (cond)) == BOOLEAN_TYPE))
warning_at (location, OPT_Wparentheses,
"the omitted middle operand in %<?:%> will always be %<true%>, "
"suggest explicit middle operand");
}
/* Give an error for storing into ARG, which is 'const'. USE indicates
how ARG was being used. */
void
readonly_error (location_t loc, tree arg, enum lvalue_use use)
{
gcc_assert (use == lv_assign || use == lv_increment || use == lv_decrement
|| use == lv_asm);
STRIP_ANY_LOCATION_WRAPPER (arg);
/* Using this macro rather than (for example) arrays of messages
ensures that all the format strings are checked at compile
time. */
#define READONLY_MSG(A, I, D, AS) (use == lv_assign ? (A) \
: (use == lv_increment ? (I) \
: (use == lv_decrement ? (D) : (AS))))
if (TREE_CODE (arg) == COMPONENT_REF)
{
if (TYPE_READONLY (TREE_TYPE (TREE_OPERAND (arg, 0))))
error_at (loc, READONLY_MSG (G_("assignment of member "
"%qD in read-only object"),
G_("increment of member "
"%qD in read-only object"),
G_("decrement of member "
"%qD in read-only object"),
G_("member %qD in read-only object "
"used as %<asm%> output")),
TREE_OPERAND (arg, 1));
else
error_at (loc, READONLY_MSG (G_("assignment of read-only member %qD"),
G_("increment of read-only member %qD"),
G_("decrement of read-only member %qD"),
G_("read-only member %qD used as %<asm%> output")),
TREE_OPERAND (arg, 1));
}
else if (VAR_P (arg))
error_at (loc, READONLY_MSG (G_("assignment of read-only variable %qD"),
G_("increment of read-only variable %qD"),
G_("decrement of read-only variable %qD"),
G_("read-only variable %qD used as %<asm%> output")),
arg);
else if (TREE_CODE (arg) == PARM_DECL)
error_at (loc, READONLY_MSG (G_("assignment of read-only parameter %qD"),
G_("increment of read-only parameter %qD"),
G_("decrement of read-only parameter %qD"),
G_("read-only parameter %qD use as %<asm%> output")),
arg);
else if (TREE_CODE (arg) == RESULT_DECL)
{
gcc_assert (c_dialect_cxx ());
error_at (loc, READONLY_MSG (G_("assignment of "
"read-only named return value %qD"),
G_("increment of "
"read-only named return value %qD"),
G_("decrement of "
"read-only named return value %qD"),
G_("read-only named return value %qD "
"used as %<asm%>output")),
arg);
}
else if (TREE_CODE (arg) == FUNCTION_DECL)
error_at (loc, READONLY_MSG (G_("assignment of function %qD"),
G_("increment of function %qD"),
G_("decrement of function %qD"),
G_("function %qD used as %<asm%> output")),
arg);
else
error_at (loc, READONLY_MSG (G_("assignment of read-only location %qE"),
G_("increment of read-only location %qE"),
G_("decrement of read-only location %qE"),
G_("read-only location %qE used as %<asm%> output")),
arg);
}
/* Print an error message for an invalid lvalue. USE says
how the lvalue is being used and so selects the error message. LOC
is the location for the error. */
void
lvalue_error (location_t loc, enum lvalue_use use)
{
switch (use)
{
case lv_assign:
error_at (loc, "lvalue required as left operand of assignment");
break;
case lv_increment:
error_at (loc, "lvalue required as increment operand");
break;
case lv_decrement:
error_at (loc, "lvalue required as decrement operand");
break;
case lv_addressof:
error_at (loc, "lvalue required as unary %<&%> operand");
break;
case lv_asm:
error_at (loc, "lvalue required in %<asm%> statement");
break;
default:
gcc_unreachable ();
}
}
/* Print an error message for an invalid indirection of type TYPE.
ERRSTRING is the name of the operator for the indirection. */
void
invalid_indirection_error (location_t loc, tree type, ref_operator errstring)
{
switch (errstring)
{
case RO_NULL:
gcc_assert (c_dialect_cxx ());
error_at (loc, "invalid type argument (have %qT)", type);
break;
case RO_ARRAY_INDEXING:
error_at (loc,
"invalid type argument of array indexing (have %qT)",
type);
break;
case RO_UNARY_STAR:
error_at (loc,
"invalid type argument of unary %<*%> (have %qT)",
type);
break;
case RO_ARROW:
error_at (loc,
"invalid type argument of %<->%> (have %qT)",
type);
break;
case RO_ARROW_STAR:
error_at (loc,
"invalid type argument of %<->*%> (have %qT)",
type);
break;
case RO_IMPLICIT_CONVERSION:
error_at (loc,
"invalid type argument of implicit conversion (have %qT)",
type);
break;
default:
gcc_unreachable ();
}
}
/* Subscripting with type char is likely to lose on a machine where
chars are signed. So warn on any machine, but optionally. Don't
warn for unsigned char since that type is safe. Don't warn for
signed char because anyone who uses that must have done so
deliberately. Furthermore, we reduce the false positive load by
warning only for non-constant value of type char.
LOC is the location of the subscripting expression. */
void
warn_array_subscript_with_type_char (location_t loc, tree index)
{
if (TYPE_MAIN_VARIANT (TREE_TYPE (index)) == char_type_node)
{
/* If INDEX has a location, use it; otherwise use LOC (the location
of the subscripting expression as a whole). */
loc = EXPR_LOC_OR_LOC (index, loc);
STRIP_ANY_LOCATION_WRAPPER (index);
if (TREE_CODE (index) != INTEGER_CST)
warning_at (loc, OPT_Wchar_subscripts,
"array subscript has type %<char%>");
}
}
/* Implement -Wparentheses for the unexpected C precedence rules, to
cover cases like x + y << z which readers are likely to
misinterpret. We have seen an expression in which CODE is a binary
operator used to combine expressions ARG_LEFT and ARG_RIGHT, which
before folding had CODE_LEFT and CODE_RIGHT. CODE_LEFT and
CODE_RIGHT may be ERROR_MARK, which means that that side of the
expression was not formed using a binary or unary operator, or it
was enclosed in parentheses. */
void
warn_about_parentheses (location_t loc, enum tree_code code,
enum tree_code code_left, tree arg_left,
enum tree_code code_right, tree arg_right)
{
if (!warn_parentheses)
return;
/* This macro tests that the expression ARG with original tree code
CODE appears to be a boolean expression. or the result of folding a
boolean expression. */
#define APPEARS_TO_BE_BOOLEAN_EXPR_P(CODE, ARG) \
(truth_value_p (TREE_CODE (ARG)) \
|| TREE_CODE (TREE_TYPE (ARG)) == BOOLEAN_TYPE \
/* Folding may create 0 or 1 integers from other expressions. */ \
|| ((CODE) != INTEGER_CST \
&& (integer_onep (ARG) || integer_zerop (ARG))))
switch (code)
{
case LSHIFT_EXPR:
if (code_left == PLUS_EXPR)
warning_at (EXPR_LOC_OR_LOC (arg_left, loc), OPT_Wparentheses,
"suggest parentheses around %<+%> inside %<<<%>");
else if (code_right == PLUS_EXPR)
warning_at (EXPR_LOC_OR_LOC (arg_right, loc), OPT_Wparentheses,
"suggest parentheses around %<+%> inside %<<<%>");
else if (code_left == MINUS_EXPR)
warning_at (EXPR_LOC_OR_LOC (arg_left, loc), OPT_Wparentheses,
"suggest parentheses around %<-%> inside %<<<%>");
else if (code_right == MINUS_EXPR)
warning_at (EXPR_LOC_OR_LOC (arg_right, loc), OPT_Wparentheses,
"suggest parentheses around %<-%> inside %<<<%>");
return;
case RSHIFT_EXPR:
if (code_left == PLUS_EXPR)
warning_at (EXPR_LOC_OR_LOC (arg_left, loc), OPT_Wparentheses,
"suggest parentheses around %<+%> inside %<>>%>");
else if (code_right == PLUS_EXPR)
warning_at (EXPR_LOC_OR_LOC (arg_right, loc), OPT_Wparentheses,
"suggest parentheses around %<+%> inside %<>>%>");
else if (code_left == MINUS_EXPR)
warning_at (EXPR_LOC_OR_LOC (arg_left, loc), OPT_Wparentheses,
"suggest parentheses around %<-%> inside %<>>%>");
else if (code_right == MINUS_EXPR)
warning_at (EXPR_LOC_OR_LOC (arg_right, loc), OPT_Wparentheses,
"suggest parentheses around %<-%> inside %<>>%>");
return;
case TRUTH_ORIF_EXPR:
if (code_left == TRUTH_ANDIF_EXPR)
warning_at (EXPR_LOC_OR_LOC (arg_left, loc), OPT_Wparentheses,
"suggest parentheses around %<&&%> within %<||%>");
else if (code_right == TRUTH_ANDIF_EXPR)
warning_at (EXPR_LOC_OR_LOC (arg_right, loc), OPT_Wparentheses,
"suggest parentheses around %<&&%> within %<||%>");
return;
case BIT_IOR_EXPR:
if (code_left == BIT_AND_EXPR || code_left == BIT_XOR_EXPR
|| code_left == PLUS_EXPR || code_left == MINUS_EXPR)
warning_at (EXPR_LOC_OR_LOC (arg_left, loc), OPT_Wparentheses,
"suggest parentheses around arithmetic in operand of %<|%>");
else if (code_right == BIT_AND_EXPR || code_right == BIT_XOR_EXPR
|| code_right == PLUS_EXPR || code_right == MINUS_EXPR)
warning_at (EXPR_LOC_OR_LOC (arg_right, loc), OPT_Wparentheses,
"suggest parentheses around arithmetic in operand of %<|%>");
/* Check cases like x|y==z */
else if (TREE_CODE_CLASS (code_left) == tcc_comparison)
warning_at (EXPR_LOC_OR_LOC (arg_left, loc), OPT_Wparentheses,
"suggest parentheses around comparison in operand of %<|%>");
else if (TREE_CODE_CLASS (code_right) == tcc_comparison)
warning_at (EXPR_LOC_OR_LOC (arg_right, loc), OPT_Wparentheses,
"suggest parentheses around comparison in operand of %<|%>");
/* Check cases like !x | y */
else if (code_left == TRUTH_NOT_EXPR
&& !APPEARS_TO_BE_BOOLEAN_EXPR_P (code_right, arg_right))
warning_at (EXPR_LOC_OR_LOC (arg_left, loc), OPT_Wparentheses,
"suggest parentheses around operand of "
"%<!%> or change %<|%> to %<||%> or %<!%> to %<~%>");
return;
case BIT_XOR_EXPR:
if (code_left == BIT_AND_EXPR
|| code_left == PLUS_EXPR || code_left == MINUS_EXPR)
warning_at (EXPR_LOC_OR_LOC (arg_left, loc), OPT_Wparentheses,
"suggest parentheses around arithmetic in operand of %<^%>");
else if (code_right == BIT_AND_EXPR
|| code_right == PLUS_EXPR || code_right == MINUS_EXPR)
warning_at (EXPR_LOC_OR_LOC (arg_right, loc), OPT_Wparentheses,
"suggest parentheses around arithmetic in operand of %<^%>");
/* Check cases like x^y==z */
else if (TREE_CODE_CLASS (code_left) == tcc_comparison)
warning_at (EXPR_LOC_OR_LOC (arg_left, loc), OPT_Wparentheses,
"suggest parentheses around comparison in operand of %<^%>");
else if (TREE_CODE_CLASS (code_right) == tcc_comparison)
warning_at (EXPR_LOC_OR_LOC (arg_right, loc), OPT_Wparentheses,
"suggest parentheses around comparison in operand of %<^%>");
return;
case BIT_AND_EXPR:
if (code_left == PLUS_EXPR)
warning_at (EXPR_LOC_OR_LOC (arg_left, loc), OPT_Wparentheses,
"suggest parentheses around %<+%> in operand of %<&%>");
else if (code_right == PLUS_EXPR)
warning_at (EXPR_LOC_OR_LOC (arg_right, loc), OPT_Wparentheses,
"suggest parentheses around %<+%> in operand of %<&%>");
else if (code_left == MINUS_EXPR)
warning_at (EXPR_LOC_OR_LOC (arg_left, loc), OPT_Wparentheses,
"suggest parentheses around %<-%> in operand of %<&%>");
else if (code_right == MINUS_EXPR)
warning_at (EXPR_LOC_OR_LOC (arg_right, loc), OPT_Wparentheses,
"suggest parentheses around %<-%> in operand of %<&%>");
/* Check cases like x&y==z */
else if (TREE_CODE_CLASS (code_left) == tcc_comparison)
warning_at (EXPR_LOC_OR_LOC (arg_left, loc), OPT_Wparentheses,
"suggest parentheses around comparison in operand of %<&%>");
else if (TREE_CODE_CLASS (code_right) == tcc_comparison)
warning_at (EXPR_LOC_OR_LOC (arg_right, loc), OPT_Wparentheses,
"suggest parentheses around comparison in operand of %<&%>");
/* Check cases like !x & y */
else if (code_left == TRUTH_NOT_EXPR
&& !APPEARS_TO_BE_BOOLEAN_EXPR_P (code_right, arg_right))
warning_at (EXPR_LOC_OR_LOC (arg_left, loc), OPT_Wparentheses,
"suggest parentheses around operand of "
"%<!%> or change %<&%> to %<&&%> or %<!%> to %<~%>");
return;
case EQ_EXPR:
if (TREE_CODE_CLASS (code_left) == tcc_comparison)
warning_at (EXPR_LOC_OR_LOC (arg_left, loc), OPT_Wparentheses,
"suggest parentheses around comparison in operand of %<==%>");
else if (TREE_CODE_CLASS (code_right) == tcc_comparison)
warning_at (EXPR_LOC_OR_LOC (arg_right, loc), OPT_Wparentheses,
"suggest parentheses around comparison in operand of %<==%>");
return;
case NE_EXPR:
if (TREE_CODE_CLASS (code_left) == tcc_comparison)
warning_at (EXPR_LOC_OR_LOC (arg_left, loc), OPT_Wparentheses,
"suggest parentheses around comparison in operand of %<!=%>");
else if (TREE_CODE_CLASS (code_right) == tcc_comparison)
warning_at (EXPR_LOC_OR_LOC (arg_right, loc), OPT_Wparentheses,
"suggest parentheses around comparison in operand of %<!=%>");
return;
default:
if (TREE_CODE_CLASS (code) == tcc_comparison)
{
if (TREE_CODE_CLASS (code_left) == tcc_comparison
&& code_left != NE_EXPR && code_left != EQ_EXPR
&& INTEGRAL_TYPE_P (TREE_TYPE (arg_left)))
warning_at (EXPR_LOC_OR_LOC (arg_left, loc), OPT_Wparentheses,
"comparisons like %<X<=Y<=Z%> do not "
"have their mathematical meaning");
else if (TREE_CODE_CLASS (code_right) == tcc_comparison
&& code_right != NE_EXPR && code_right != EQ_EXPR
&& INTEGRAL_TYPE_P (TREE_TYPE (arg_right)))
warning_at (EXPR_LOC_OR_LOC (arg_right, loc), OPT_Wparentheses,
"comparisons like %<X<=Y<=Z%> do not "
"have their mathematical meaning");
}
return;
}
#undef NOT_A_BOOLEAN_EXPR_P
}
/* If LABEL (a LABEL_DECL) has not been used, issue a warning. */
void
warn_for_unused_label (tree label)
{
if (!TREE_USED (label))
{
if (DECL_INITIAL (label))
warning (OPT_Wunused_label, "label %q+D defined but not used", label);
else
warning (OPT_Wunused_label, "label %q+D declared but not defined", label);
}
else if (asan_sanitize_use_after_scope ())
{
if (asan_used_labels == NULL)
asan_used_labels = new hash_set<tree> (16);
asan_used_labels->add (label);
}
}
/* Warn for division by zero according to the value of DIVISOR. LOC
is the location of the division operator. */
void
warn_for_div_by_zero (location_t loc, tree divisor)
{
/* If DIVISOR is zero, and has integral or fixed-point type, issue a warning
about division by zero. Do not issue a warning if DIVISOR has a
floating-point type, since we consider 0.0/0.0 a valid way of
generating a NaN. */
if (c_inhibit_evaluation_warnings == 0
&& (integer_zerop (divisor) || fixed_zerop (divisor)))
warning_at (loc, OPT_Wdiv_by_zero, "division by zero");
}
/* Warn for patterns where memset appears to be used incorrectly. The
warning location should be LOC. ARG0, and ARG2 are the first and
last arguments to the call, while LITERAL_ZERO_MASK has a 1 bit for
each argument that was a literal zero. */
void
warn_for_memset (location_t loc, tree arg0, tree arg2,
int literal_zero_mask)
{
arg0 = fold_for_warn (arg0);
arg2 = fold_for_warn (arg2);
if (warn_memset_transposed_args
&& integer_zerop (arg2)
&& (literal_zero_mask & (1 << 2)) != 0
&& (literal_zero_mask & (1 << 1)) == 0)
warning_at (loc, OPT_Wmemset_transposed_args,
"%<memset%> used with constant zero length "
"parameter; this could be due to transposed "
"parameters");
if (warn_memset_elt_size && TREE_CODE (arg2) == INTEGER_CST)
{
STRIP_NOPS (arg0);
if (TREE_CODE (arg0) == ADDR_EXPR)
arg0 = TREE_OPERAND (arg0, 0);
tree type = TREE_TYPE (arg0);
if (type != NULL_TREE && TREE_CODE (type) == ARRAY_TYPE)
{
tree elt_type = TREE_TYPE (type);
tree domain = TYPE_DOMAIN (type);
if (COMPLETE_TYPE_P (elt_type)
&& !integer_onep (TYPE_SIZE_UNIT (elt_type))
&& domain != NULL_TREE
&& TYPE_MAX_VALUE (domain)
&& TYPE_MIN_VALUE (domain)
&& integer_zerop (TYPE_MIN_VALUE (domain))
&& integer_onep (fold_build2 (MINUS_EXPR, domain,
arg2,
TYPE_MAX_VALUE (domain))))
warning_at (loc, OPT_Wmemset_elt_size,
"%<memset%> used with length equal to "
"number of elements without multiplication "
"by element size");
}
}
}
/* Subroutine of build_binary_op. Give warnings for comparisons
between signed and unsigned quantities that may fail. Do the
checking based on the original operand trees ORIG_OP0 and ORIG_OP1,
so that casts will be considered, but default promotions won't
be.
LOCATION is the location of the comparison operator.
The arguments of this function map directly to local variables
of build_binary_op. */
void
warn_for_sign_compare (location_t location,
tree orig_op0, tree orig_op1,
tree op0, tree op1,
tree result_type, enum tree_code resultcode)
{
if (error_operand_p (orig_op0) || error_operand_p (orig_op1))
return;
int op0_signed = !TYPE_UNSIGNED (TREE_TYPE (orig_op0));
int op1_signed = !TYPE_UNSIGNED (TREE_TYPE (orig_op1));
int unsignedp0, unsignedp1;
/* Do not warn if the comparison is being done in a signed type,
since the signed type will only be chosen if it can represent
all the values of the unsigned type. */
if (!TYPE_UNSIGNED (result_type))
/* OK */;
/* Do not warn if both operands are unsigned. */
else if (op0_signed == op1_signed)
/* OK */;
else
{
tree sop, uop, base_type;
bool ovf;
if (op0_signed)
sop = orig_op0, uop = orig_op1;
else
sop = orig_op1, uop = orig_op0;
sop = fold_for_warn (sop);
uop = fold_for_warn (uop);
STRIP_TYPE_NOPS (sop);
STRIP_TYPE_NOPS (uop);
base_type = (TREE_CODE (result_type) == COMPLEX_TYPE
? TREE_TYPE (result_type) : result_type);
/* Do not warn if the signed quantity is an unsuffixed integer
literal (or some static constant expression involving such
literals or a conditional expression involving such literals)
and it is non-negative. */
if (tree_expr_nonnegative_warnv_p (sop, &ovf))
/* OK */;
/* Do not warn if the comparison is an equality operation, the
unsigned quantity is an integral constant, and it would fit
in the result if the result were signed. */
else if (TREE_CODE (uop) == INTEGER_CST
&& (resultcode == EQ_EXPR || resultcode == NE_EXPR)
&& int_fits_type_p (uop, c_common_signed_type (base_type)))
/* OK */;
/* In C, do not warn if the unsigned quantity is an enumeration
constant and its maximum value would fit in the result if the
result were signed. */
else if (!c_dialect_cxx() && TREE_CODE (uop) == INTEGER_CST
&& TREE_CODE (TREE_TYPE (uop)) == ENUMERAL_TYPE
&& int_fits_type_p (TYPE_MAX_VALUE (TREE_TYPE (uop)),
c_common_signed_type (base_type)))
/* OK */;
else
warning_at (location, OPT_Wsign_compare,
"comparison of integer expressions of different "
"signedness: %qT and %qT", TREE_TYPE (orig_op0),
TREE_TYPE (orig_op1));
}
/* Warn if two unsigned values are being compared in a size larger
than their original size, and one (and only one) is the result of
a `~' operator. This comparison will always fail.
Also warn if one operand is a constant, and the constant does not
have all bits set that are set in the ~ operand when it is
extended. */
op0 = c_common_get_narrower (op0, &unsignedp0);
op1 = c_common_get_narrower (op1, &unsignedp1);
if ((TREE_CODE (op0) == BIT_NOT_EXPR)
^ (TREE_CODE (op1) == BIT_NOT_EXPR))
{
if (TREE_CODE (op0) == BIT_NOT_EXPR)
op0 = c_common_get_narrower (TREE_OPERAND (op0, 0), &unsignedp0);
if (TREE_CODE (op1) == BIT_NOT_EXPR)
op1 = c_common_get_narrower (TREE_OPERAND (op1, 0), &unsignedp1);
if (tree_fits_shwi_p (op0) || tree_fits_shwi_p (op1))
{
tree primop;
HOST_WIDE_INT constant, mask;
int unsignedp;
unsigned int bits;
if (tree_fits_shwi_p (op0))
{
primop = op1;
unsignedp = unsignedp1;
constant = tree_to_shwi (op0);
}
else
{
primop = op0;
unsignedp = unsignedp0;
constant = tree_to_shwi (op1);
}
bits = TYPE_PRECISION (TREE_TYPE (primop));
if (bits < TYPE_PRECISION (result_type)
&& bits < HOST_BITS_PER_LONG && unsignedp)
{
mask = HOST_WIDE_INT_M1U << bits;
if ((mask & constant) != mask)
{
if (constant == 0)
warning_at (location, OPT_Wsign_compare,
"promoted bitwise complement of an unsigned "
"value is always nonzero");
else
warning_at (location, OPT_Wsign_compare,
"comparison of promoted bitwise complement "
"of an unsigned value with constant");
}
}
}
else if (unsignedp0 && unsignedp1
&& (TYPE_PRECISION (TREE_TYPE (op0))
< TYPE_PRECISION (result_type))
&& (TYPE_PRECISION (TREE_TYPE (op1))
< TYPE_PRECISION (result_type)))
warning_at (location, OPT_Wsign_compare,
"comparison of promoted bitwise complement "
"of an unsigned value with unsigned");
}
}
/* RESULT_TYPE is the result of converting TYPE1 and TYPE2 to a common
type via c_common_type. If -Wdouble-promotion is in use, and the
conditions for warning have been met, issue a warning. GMSGID is
the warning message. It must have two %T specifiers for the type
that was converted (generally "float") and the type to which it was
converted (generally "double), respectively. LOC is the location
to which the warning should refer. */
void
do_warn_double_promotion (tree result_type, tree type1, tree type2,
const char *gmsgid, location_t loc)
{
tree source_type;
if (!warn_double_promotion)
return;
/* If the conversion will not occur at run-time, there is no need to
warn about it. */
if (c_inhibit_evaluation_warnings)
return;
/* If an invalid conversion has occurred, don't warn. */
if (result_type == error_mark_node)
return;
if (TYPE_MAIN_VARIANT (result_type) != double_type_node
&& TYPE_MAIN_VARIANT (result_type) != complex_double_type_node)
return;
if (TYPE_MAIN_VARIANT (type1) == float_type_node
|| TYPE_MAIN_VARIANT (type1) == complex_float_type_node)
source_type = type1;
else if (TYPE_MAIN_VARIANT (type2) == float_type_node
|| TYPE_MAIN_VARIANT (type2) == complex_float_type_node)
source_type = type2;
else
return;
warning_at (loc, OPT_Wdouble_promotion, gmsgid, source_type, result_type);
}
/* Possibly warn about unused parameters. */
void
do_warn_unused_parameter (tree fn)
{
tree decl;
for (decl = DECL_ARGUMENTS (fn);
decl; decl = DECL_CHAIN (decl))
if (!TREE_USED (decl) && TREE_CODE (decl) == PARM_DECL
&& DECL_NAME (decl) && !DECL_ARTIFICIAL (decl)
&& !warning_suppressed_p (decl, OPT_Wunused_parameter))
warning_at (DECL_SOURCE_LOCATION (decl), OPT_Wunused_parameter,
"unused parameter %qD", decl);
}
/* If DECL is a typedef that is declared in the current function,
record it for the purpose of -Wunused-local-typedefs. */
void
record_locally_defined_typedef (tree decl)
{
struct c_language_function *l;
if (!warn_unused_local_typedefs
|| cfun == NULL
/* if this is not a locally defined typedef then we are not
interested. */
|| !is_typedef_decl (decl)
|| !decl_function_context (decl))
return;
l = (struct c_language_function *) cfun->language;
vec_safe_push (l->local_typedefs, decl);
}
/* If T is a TYPE_DECL declared locally, mark it as used. */
void
maybe_record_typedef_use (tree t)
{
if (!is_typedef_decl (t))
return;
TREE_USED (t) = true;
}
/* Warn if there are some unused locally defined typedefs in the
current function. */
void
maybe_warn_unused_local_typedefs (void)
{
int i;
tree decl;
/* The number of times we have emitted -Wunused-local-typedefs
warnings. If this is different from errorcount, that means some
unrelated errors have been issued. In which case, we'll avoid
emitting "unused-local-typedefs" warnings. */
static int unused_local_typedefs_warn_count;
struct c_language_function *l;
if (cfun == NULL)
return;
if ((l = (struct c_language_function *) cfun->language) == NULL)
return;
if (warn_unused_local_typedefs
&& errorcount == unused_local_typedefs_warn_count)
{
FOR_EACH_VEC_SAFE_ELT (l->local_typedefs, i, decl)
if (!TREE_USED (decl))
warning_at (DECL_SOURCE_LOCATION (decl),
OPT_Wunused_local_typedefs,
"typedef %qD locally defined but not used", decl);
unused_local_typedefs_warn_count = errorcount;
}
vec_free (l->local_typedefs);
}
/* If we're creating an if-else-if condition chain, first see if we
already have this COND in the CHAIN. If so, warn and don't add COND
into the vector, otherwise add the COND there. LOC is the location
of COND. */
void
warn_duplicated_cond_add_or_warn (location_t loc, tree cond, vec<tree> **chain)
{
/* No chain has been created yet. Do nothing. */
if (*chain == NULL)
return;
if (TREE_SIDE_EFFECTS (cond))
{
/* Uh-oh! This condition has a side-effect, thus invalidates
the whole chain. */
delete *chain;
*chain = NULL;
return;
}
unsigned int ix;
tree t;
bool found = false;
FOR_EACH_VEC_ELT (**chain, ix, t)
if (operand_equal_p (cond, t, 0))
{
auto_diagnostic_group d;
if (warning_at (loc, OPT_Wduplicated_cond,
"duplicated %<if%> condition"))
inform (EXPR_LOCATION (t), "previously used here");
found = true;
break;
}
if (!found
&& !CONSTANT_CLASS_P (cond)
/* Don't infinitely grow the chain. */
&& (*chain)->length () < 512)
(*chain)->safe_push (cond);
}
/* Check and possibly warn if two declarations have contradictory
attributes, such as always_inline vs. noinline. */
bool
diagnose_mismatched_attributes (tree olddecl, tree newdecl)
{
bool warned = false;
tree a1 = lookup_attribute ("optimize", DECL_ATTRIBUTES (olddecl));
tree a2 = lookup_attribute ("optimize", DECL_ATTRIBUTES (newdecl));
/* An optimization attribute applied on a declaration after the
definition is likely not what the user wanted. */
if (a2 != NULL_TREE
&& DECL_SAVED_TREE (olddecl) != NULL_TREE
&& (a1 == NULL_TREE || !attribute_list_equal (a1, a2)))
warned |= warning (OPT_Wattributes,
"optimization attribute on %qD follows "
"definition but the attribute doesn%'t match",
newdecl);
/* Diagnose inline __attribute__ ((noinline)) which is silly. */
if (DECL_DECLARED_INLINE_P (newdecl)
&& DECL_UNINLINABLE (olddecl)
&& lookup_attribute ("noinline", DECL_ATTRIBUTES (olddecl)))
warned |= warning (OPT_Wattributes, "inline declaration of %qD follows "
"declaration with attribute %<noinline%>", newdecl);
else if (DECL_DECLARED_INLINE_P (olddecl)
&& DECL_UNINLINABLE (newdecl)
&& lookup_attribute ("noinline", DECL_ATTRIBUTES (newdecl)))
warned |= warning (OPT_Wattributes, "declaration of %q+D with attribute "
"%<noinline%> follows inline declaration", newdecl);
return warned;
}
/* Warn if signed left shift overflows. We don't warn
about left-shifting 1 into the sign bit in C++14; cf.
<http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2012/n3367.html#1457>
and don't warn for C++20 at all, as signed left shifts never
overflow.
LOC is a location of the shift; OP0 and OP1 are the operands.
Return true if an overflow is detected, false otherwise. */
bool
maybe_warn_shift_overflow (location_t loc, tree op0, tree op1)
{
if (TREE_CODE (op0) != INTEGER_CST
|| TREE_CODE (op1) != INTEGER_CST)
return false;
tree type0 = TREE_TYPE (op0);
unsigned int prec0 = TYPE_PRECISION (type0);
/* Left-hand operand must be signed. */
if (TYPE_UNSIGNED (type0) || cxx_dialect >= cxx20)
return false;
unsigned int min_prec = (wi::min_precision (wi::to_wide (op0), SIGNED)
+ TREE_INT_CST_LOW (op1));
/* Handle the case of left-shifting 1 into the sign bit.
* However, shifting 1 _out_ of the sign bit, as in
* INT_MIN << 1, is considered an overflow.
*/
if (!tree_int_cst_sign_bit (op0) && min_prec == prec0 + 1)
{
/* Never warn for C++14 onwards. */
if (cxx_dialect >= cxx14)
return false;
/* Otherwise only if -Wshift-overflow=2. But return
true to signal an overflow for the sake of integer
constant expressions. */
if (warn_shift_overflow < 2)
return true;
}
bool overflowed = min_prec > prec0;
if (overflowed && c_inhibit_evaluation_warnings == 0)
warning_at (loc, OPT_Wshift_overflow_,
"result of %qE requires %u bits to represent, "
"but %qT only has %u bits",
build2_loc (loc, LSHIFT_EXPR, type0, op0, op1),
min_prec, type0, prec0);
return overflowed;
}
/* Warn about boolean expression compared with an integer value different
from true/false. Warns also e.g. about "(i1 == i2) == 2".
LOC is the location of the comparison, CODE is its code, OP0 and OP1
are the operands of the comparison. The caller must ensure that
either operand is a boolean expression. */
void
maybe_warn_bool_compare (location_t loc, enum tree_code code, tree op0,
tree op1)
{
if (TREE_CODE_CLASS (code) != tcc_comparison)
return;
tree f, cst;
if (f = fold_for_warn (op0),
TREE_CODE (f) == INTEGER_CST)
cst = op0 = f;
else if (f = fold_for_warn (op1),
TREE_CODE (f) == INTEGER_CST)
cst = op1 = f;
else
return;
if (!integer_zerop (cst) && !integer_onep (cst))
{
int sign = (TREE_CODE (op0) == INTEGER_CST
? tree_int_cst_sgn (cst) : -tree_int_cst_sgn (cst));
if (code == EQ_EXPR
|| ((code == GT_EXPR || code == GE_EXPR) && sign < 0)
|| ((code == LT_EXPR || code == LE_EXPR) && sign > 0))
warning_at (loc, OPT_Wbool_compare, "comparison of constant %qE "
"with boolean expression is always false", cst);
else
warning_at (loc, OPT_Wbool_compare, "comparison of constant %qE "
"with boolean expression is always true", cst);
}
else if (integer_zerop (cst) || integer_onep (cst))
{
/* If the non-constant operand isn't of a boolean type, we
don't want to warn here. */
tree noncst = TREE_CODE (op0) == INTEGER_CST ? op1 : op0;
/* Handle booleans promoted to integers. */
if (bool_promoted_to_int_p (noncst))
/* Warn. */;
else if (TREE_CODE (TREE_TYPE (noncst)) != BOOLEAN_TYPE
&& !truth_value_p (TREE_CODE (noncst)))
return;
/* Do some magic to get the right diagnostics. */
bool flag = TREE_CODE (op0) == INTEGER_CST;
flag = integer_zerop (cst) ? flag : !flag;
if ((code == GE_EXPR && !flag) || (code == LE_EXPR && flag))
warning_at (loc, OPT_Wbool_compare, "comparison of constant %qE "
"with boolean expression is always true", cst);
else if ((code == LT_EXPR && !flag) || (code == GT_EXPR && flag))
warning_at (loc, OPT_Wbool_compare, "comparison of constant %qE "
"with boolean expression is always false", cst);
}
}
/* Warn if an argument at position param_pos is passed to a
restrict-qualified param, and it aliases with another argument.
Return true if a warning has been issued. */
bool
warn_for_restrict (unsigned param_pos, tree *argarray, unsigned nargs)
{
tree arg = argarray[param_pos];
if (TREE_VISITED (arg) || integer_zerop (arg))
return false;
location_t loc = EXPR_LOC_OR_LOC (arg, input_location);
gcc_rich_location richloc (loc);
unsigned i;
auto_vec<int, 16> arg_positions;
for (i = 0; i < nargs; i++)
{
if (i == param_pos)
continue;
tree current_arg = argarray[i];
if (operand_equal_p (arg, current_arg, 0))
{
TREE_VISITED (current_arg) = 1;
arg_positions.safe_push (i + 1);
}
}
if (arg_positions.is_empty ())
return false;
int pos;
FOR_EACH_VEC_ELT (arg_positions, i, pos)
{
arg = argarray[pos - 1];
if (EXPR_HAS_LOCATION (arg))
richloc.add_range (EXPR_LOCATION (arg));
}
return warning_n (&richloc, OPT_Wrestrict, arg_positions.length (),
"passing argument %i to %qs-qualified parameter"
" aliases with argument %Z",
"passing argument %i to %qs-qualified parameter"
" aliases with arguments %Z",
param_pos + 1, "restrict", arg_positions.address (),
arg_positions.length ());
}
/* Callback function to determine whether an expression TP or one of its
subexpressions comes from macro expansion. Used to suppress bogus
warnings. */
static tree
expr_from_macro_expansion_r (tree *tp, int *, void *)
{
if (CAN_HAVE_LOCATION_P (*tp)
&& from_macro_expansion_at (EXPR_LOCATION (*tp)))
return integer_zero_node;
return NULL_TREE;
}
/* Possibly warn when an if-else has identical branches. */
static void
do_warn_duplicated_branches (tree expr)
{
tree thenb = COND_EXPR_THEN (expr);
tree elseb = COND_EXPR_ELSE (expr);
/* Don't bother if any of the branches is missing. */
if (thenb == NULL_TREE || elseb == NULL_TREE)
return;
/* And don't warn for empty statements. */
if (TREE_CODE (thenb) == NOP_EXPR
&& TREE_TYPE (thenb) == void_type_node
&& TREE_OPERAND (thenb, 0) == size_zero_node)
return;
/* ... or empty branches. */
if (TREE_CODE (thenb) == STATEMENT_LIST
&& STATEMENT_LIST_HEAD (thenb) == NULL)
return;
/* Compute the hash of the then branch. */
inchash::hash hstate0 (0);
inchash::add_expr (thenb, hstate0);
hashval_t h0 = hstate0.end ();
/* Compute the hash of the else branch. */
inchash::hash hstate1 (0);
inchash::add_expr (elseb, hstate1);
hashval_t h1 = hstate1.end ();
/* Compare the hashes. */
if (h0 == h1
&& operand_equal_p (thenb, elseb, OEP_LEXICOGRAPHIC
| OEP_ADDRESS_OF_SAME_FIELD)
/* Don't warn if any of the branches or their subexpressions comes
from a macro. */
&& !walk_tree_without_duplicates (&thenb, expr_from_macro_expansion_r,
NULL)
&& !walk_tree_without_duplicates (&elseb, expr_from_macro_expansion_r,
NULL))
warning_at (EXPR_LOCATION (expr), OPT_Wduplicated_branches,
"this condition has identical branches");
}
/* Callback for c_genericize to implement -Wduplicated-branches. */