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------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- S E M _ E V A L --
-- --
-- S p e c --
-- --
-- Copyright (C) 1992-2021, Free Software Foundation, Inc. --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
-- ware Foundation; either version 3, or (at your option) any later ver- --
-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT 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 distributed with GNAT; see file COPYING3. If not, go to --
-- http://www.gnu.org/licenses for a complete copy of the license. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
-- This package contains various subprograms involved in compile time
-- evaluation of expressions and checks for staticness of expressions and
-- types. It also contains the circuitry for checking for violations of pure
-- and preelaborated conditions (this naturally goes here, since these rules
-- involve consideration of staticness).
-- Note: the static evaluation for attributes is found in Sem_Attr even though
-- logically it belongs here. We have done this so that it is easier to add
-- new attributes to GNAT.
with Types; use Types;
with Uintp; use Uintp;
with Urealp; use Urealp;
package Sem_Eval is
------------------------------------
-- Handling of Static Expressions --
------------------------------------
-- This package contains a set of routines that process individual
-- subexpression nodes with the objective of folding (precomputing) the
-- value of static expressions that are known at compile time and properly
-- computing the setting of two flags that appear in every subexpression
-- node:
-- Is_Static_Expression
-- True for static expressions, as defined in RM-4.9.
-- Raises_Constraint_Error
-- This flag indicates that it is known at compile time that the
-- evaluation of an expression raises constraint error. If the
-- expression is static, and this flag is off, then it is also known at
-- compile time that the expression does not raise constraint error
-- (i.e. the flag is accurate for static expressions, and conservative
-- for non-static expressions.
-- See also Is_OK_Static_Expression, which is True for static
-- expressions that do not raise Constraint_Error. This is used in most
-- legality checks, because static expressions that raise Constraint_Error
-- are usually illegal.
-- See also Compile_Time_Known_Value, which is True for an expression whose
-- value is known at compile time. In this case, the expression is folded
-- to a literal or to a constant that is itself (recursively) either a
-- literal or a constant
-- Is_[OK_]Static_Expression are used for legality checks, whereas
-- Compile_Time_Known_Value is used for optimization purposes.
-- When we are analyzing and evaluating static expressions, we propagate
-- both flags. Usually if a subexpression raises a Constraint_Error, then
-- so will its parent expression, and Raise_Constraint_Error will be
-- propagated to this parent. The exception is conditional cases like
-- (True or else 1/0 = 0), which results in an expression that has the
-- Is_Static_Expression flag True, and Raises_Constraint_Error False. Even
-- though 1/0 would raise an exception, the right operand is never actually
-- executed, so the expression as a whole does not raise CE.
-- Finally, the case of static predicates. These are applied only to entire
-- expressions, not to subexpressions, so we do not have the case of having
-- to propagate this information. We handle this case simply by resetting
-- the Is_Static_Expression flag if a static predicate fails. Note that we
-- can't use this simpler approach for the constraint error case because of
-- the (True or else 1/0 = 0) example discussed above.
-------------------------------
-- Compile-Time Known Values --
-------------------------------
-- For most legality checking purposes the flag Is_Static_Expression
-- defined in Sinfo should be used. This package also provides a routine
-- called Is_OK_Static_Expression which in addition of checking that an
-- expression is static in the RM 4.9 sense, it checks that the expression
-- does not raise constraint error. In fact for certain legality checks not
-- only do we need to ascertain that the expression is static, but we must
-- also ensure that it does not raise constraint error.
-- Neither of Is_Static_Expression and Is_OK_Static_Expression should be
-- used for compile time evaluation purposes. In fact certain expression
-- whose value may be known at compile time are not static in the RM 4.9
-- sense. A typical example is:
-- C : constant Integer := Record_Type'Size;
-- The expression 'C' is not static in the technical RM sense, but for many
-- simple record types, the size is in fact known at compile time. When we
-- are trying to perform compile time constant folding (for instance for
-- expressions like C + 1, Is_Static_Expression or Is_OK_Static_Expression
-- are not the right functions to test if folding is possible. Instead, we
-- use Compile_Time_Known_Value. All static expressions that do not raise
-- constraint error (i.e. those for which Is_OK_Static_Expression is true)
-- are known at compile time, but as shown by the above example, there may
-- be cases of non-static expressions which are known at compile time.
-----------------
-- Subprograms --
-----------------
procedure Check_Expression_Against_Static_Predicate
(Expr : Node_Id;
Typ : Entity_Id;
Static_Failure_Is_Error : Boolean := False);
-- Determine whether an arbitrary expression satisfies the static predicate
-- of a type. The routine does nothing if Expr is not known at compile time
-- or Typ lacks a static predicate; otherwise it may emit a warning if the
-- expression is prohibited by the predicate, or if Static_Failure_Is_Error
-- is True then an error will be flagged. If the expression is a static
-- expression, it fails a predicate that was not explicitly stated to be
-- a dynamic predicate, and Static_Failure_Is_Error is False, then an
-- additional warning is given, and the flag Is_Static_Expression is reset
-- on Expr.
procedure Check_Non_Static_Context (N : Node_Id);
-- Deals with the special check required for a static expression that
-- appears in a non-static context, i.e. is not part of a larger static
-- expression (see RM 4.9(35)), i.e. the value of the expression must be
-- within the base range of the base type of its expected type. A check is
-- also made for expressions that are inside the base range, but outside
-- the range of the expected subtype (this is a warning message rather than
-- an illegality).
--
-- Note: most cases of non-static context checks are handled within
-- Sem_Eval itself, including all cases of expressions at the outer level
-- (i.e. those that are not a subexpression). Currently the only outside
-- customer for this procedure is Sem_Attr (because Eval_Attribute is
-- there). There is also one special case arising from ranges (see body of
-- Resolve_Range).
--
-- Note: this procedure is also called by GNATprove on real literals
-- that are not sub-expressions of static expressions, to convert them to
-- machine numbers, as GNATprove cannot perform this conversion contrary
-- to gigi.
procedure Check_String_Literal_Length (N : Node_Id; Ttype : Entity_Id);
-- N is either a string literal, or a constraint error node. In the latter
-- case, the situation is already dealt with, and the call has no effect.
-- In the former case, if the target type, Ttyp is constrained, then a
-- check is made to see if the string literal is of appropriate length.
function Checking_Potentially_Static_Expression return Boolean;
-- Returns True if the checking for potentially static expressions is
-- enabled; otherwise returns False.
procedure Set_Checking_Potentially_Static_Expression (Value : Boolean);
-- Enables checking for potentially static expressions if Value is True,
-- and disables such checking if Value is False.
type Compare_Result is (LT, LE, EQ, GT, GE, NE, Unknown);
subtype Compare_GE is Compare_Result range EQ .. GE;
subtype Compare_LE is Compare_Result range LT .. EQ;
-- Result subtypes for Compile_Time_Compare subprograms
function Compile_Time_Compare
(L, R : Node_Id;
Assume_Valid : Boolean) return Compare_Result;
pragma Inline (Compile_Time_Compare);
-- Given two expression nodes, finds out whether it can be determined at
-- compile time how the runtime values will compare. An Unknown result
-- means that the result of a comparison cannot be determined at compile
-- time, otherwise the returned result indicates the known result of the
-- comparison, given as tightly as possible (i.e. EQ or LT is preferred
-- returned value to LE). If Assume_Valid is true, the result reflects
-- the result of assuming that entities involved in the comparison have
-- valid representations. If Assume_Valid is false, then the base type of
-- any involved entity is used so that no assumption of validity is made.
function Compile_Time_Compare
(L, R : Node_Id;
Diff : access Uint;
Assume_Valid : Boolean;
Rec : Boolean := False) return Compare_Result;
-- This version of Compile_Time_Compare returns extra information if the
-- result is GT or LT. In these cases, if the magnitude of the difference
-- can be determined at compile time, this (positive) magnitude is returned
-- in Diff.all. If the magnitude of the difference cannot be determined
-- then Diff.all contains No_Uint on return. Rec is a parameter that is set
-- True for a recursive call from within Compile_Time_Compare to avoid some
-- infinite recursion cases. It should never be set by a client.
function Compile_Time_Known_Bounds (T : Entity_Id) return Boolean;
-- If T is an array whose index bounds are all known at compile time, then
-- True is returned. If T is not an array type, or one or more of its index
-- bounds is not known at compile time, then False is returned.
function Compile_Time_Known_Value (Op : Node_Id) return Boolean;
-- Returns true if Op is an expression not raising Constraint_Error whose
-- value is known at compile time and for which a call to Expr_Value can
-- be used to determine this value. This is always true if Op is a static
-- expression, but can also be true for expressions which are technically
-- non-static but which are in fact known at compile time. Some examples of
-- such expressions are the static lower bound of a non-static range or the
-- value of a constant object whose initial value is itself compile time
-- known in the sense of this routine. Note that this routine is defended
-- against unanalyzed expressions. Such expressions will not cause a
-- blowup, they may cause pessimistic (i.e. False) results to be returned.
-- In general we take a pessimistic view. False does not mean the value
-- could not be known at compile time, but True means that absolutely
-- definition it is known at compile time and it is safe to call
-- Expr_Value[_XX] on the expression Op.
--
-- Note that we don't define precisely the set of expressions that return
-- True. Callers should not make any assumptions regarding the value that
-- is returned for non-static expressions. Functional behavior should never
-- be affected by whether a given non-static expression returns True or
-- False when this function is called. In other words this is purely for
-- efficiency optimization purposes. The code generated can often be more
-- efficient with compile time known values, e.g. range analysis for the
-- purpose of removing checks is more effective if we know precise bounds.
-- WARNING: There is a matching C declaration of this subprogram in fe.h
function Compile_Time_Known_Value_Or_Aggr (Op : Node_Id) return Boolean;
-- Similar to Compile_Time_Known_Value, but also returns True if the value
-- is a compile-time-known aggregate, i.e. an aggregate all of whose
-- constituent expressions are either compile-time-known values (based on
-- calling Compile_Time_Known_Value) or compile-time-known aggregates.
-- Note that the aggregate could still involve run-time checks that might
-- fail (such as for subtype checks in component associations), but the
-- evaluation of the expressions themselves will not raise an exception.
function CRT_Safe_Compile_Time_Known_Value (Op : Node_Id) return Boolean;
-- In the case of configurable run-times, there may be an issue calling
-- Compile_Time_Known_Value with non-static expressions where the legality
-- of the program is not well-defined. Consider this example:
--
-- X := B ** C;
--
-- Now if C is compile time known, and has the value 4, then inline code
-- can be generated at compile time, instead of calling a run-time routine.
-- That's fine in the normal case, but when we have a configurable run-time
-- the run-time routine may not be available. This means that the program
-- will be rejected if C is not known at compile time. We don't want the
-- legality of a program to depend on how clever the implementation of this
-- function is. If the run-time in use lacks the exponentiation routine,
-- then what we say is that exponentiation is permitted if the exponent is
-- officially static and has a value in the range 0 .. 4.
--
-- In a case like this, we use CRT_Safe_Compile_Time_Known_Value to avoid
-- this effect. This routine will return False for a non-static expression
-- if we are in configurable run-time mode, even if the expression would
-- normally be considered compile-time known.
function Expr_Rep_Value (N : Node_Id) return Uint;
-- This is identical to Expr_Value, except in the case of enumeration
-- literals of types for which an enumeration representation clause has
-- been given, in which case it returns the representation value rather
-- than the pos value. This is the value that is needed for generating code
-- sequences, while the Expr_Value value is appropriate for compile time
-- constraint errors or getting the logical value. Note that this function
-- does NOT concern itself with biased values, if the caller needs a
-- properly biased value, the subtraction of the bias must be handled
-- explicitly.
function Expr_Value (N : Node_Id) return Uint;
-- Returns the folded value of the expression N. This function is called in
-- instances where it has already been determined that the expression is
-- static or its value is compile time known (Compile_Time_Known_Value (N)
-- returns True). This version is used for integer values, and enumeration
-- or character literals. In the latter two cases, the value returned is
-- the Pos value in the relevant enumeration type. It can also be used for
-- fixed-point values, in which case it returns the corresponding integer
-- value, but it cannot be used for floating-point values. Finally, it can
-- also be used for the Null access value, as well as for the result of an
-- unchecked conversion of the aforementioned handled values.
function Expr_Value_E (N : Node_Id) return Entity_Id;
-- Returns the folded value of the expression. This function is called in
-- instances where it has already been determined that the expression is
-- static or its value known at compile time. This version is used for
-- enumeration types and returns the corresponding enumeration literal.
function Expr_Value_R (N : Node_Id) return Ureal;
-- Returns the folded value of the expression. This function is called in
-- instances where it has already been determined that the expression is
-- static or its value known at compile time. This version is used for real
-- values (including both the floating-point and fixed-point cases). In the
-- case of a fixed-point type, the real value is returned (cf above version
-- returning Uint).
function Expr_Value_S (N : Node_Id) return Node_Id;
-- Returns the folded value of the expression. This function is called
-- in instances where it has already been determined that the expression
-- is static or its value is known at compile time. This version is used
-- for string types and returns the corresponding N_String_Literal node.
procedure Eval_Actual (N : Node_Id);
procedure Eval_Allocator (N : Node_Id);
procedure Eval_Arithmetic_Op (N : Node_Id);
procedure Eval_Call (N : Node_Id);
procedure Eval_Case_Expression (N : Node_Id);
procedure Eval_Character_Literal (N : Node_Id);
procedure Eval_Concatenation (N : Node_Id);
procedure Eval_Entity_Name (N : Node_Id);
procedure Eval_If_Expression (N : Node_Id);
procedure Eval_Indexed_Component (N : Node_Id);
procedure Eval_Integer_Literal (N : Node_Id);
procedure Eval_Logical_Op (N : Node_Id);
procedure Eval_Membership_Op (N : Node_Id);
procedure Eval_Named_Integer (N : Node_Id);
procedure Eval_Named_Real (N : Node_Id);
procedure Eval_Op_Expon (N : Node_Id);
procedure Eval_Op_Not (N : Node_Id);
procedure Eval_Real_Literal (N : Node_Id);
procedure Eval_Relational_Op (N : Node_Id);
procedure Eval_Selected_Component (N : Node_Id);
procedure Eval_Shift (N : Node_Id);
procedure Eval_Short_Circuit (N : Node_Id);
procedure Eval_Slice (N : Node_Id);
procedure Eval_String_Literal (N : Node_Id);
procedure Eval_Qualified_Expression (N : Node_Id);
procedure Eval_Type_Conversion (N : Node_Id);
procedure Eval_Unary_Op (N : Node_Id);
procedure Eval_Unchecked_Conversion (N : Node_Id);
procedure Flag_Non_Static_Expr (Msg : String; Expr : Node_Id);
-- This procedure is called after it has been determined that Expr is not
-- static when it is required to be. Msg is the text of a message that
-- explains the error. This procedure checks if an error is already posted
-- on Expr, if so, it does nothing unless All_Errors_Mode is set in which
-- case this flag is ignored. Otherwise the given message is posted using
-- Error_Msg_F, and then Why_Not_Static is called on Expr to generate
-- additional messages. The string given as Msg should end with ! to make
-- it an unconditional message, to ensure that if it is posted, the entire
-- set of messages is all posted.
procedure Fold_Str (N : Node_Id; Val : String_Id; Static : Boolean);
-- Rewrite N with a new N_String_Literal node as the result of the compile
-- time evaluation of the node N. Val is the resulting string value from
-- the folding operation. The Is_Static_Expression flag is set in the
-- result node. The result is fully analyzed and resolved. Static indicates
-- whether the result should be considered static or not (True = consider
-- static). The point here is that normally all string literals are static,
-- but if this was the result of some sequence of evaluation where values
-- were known at compile time but not static, then the result is not
-- static. The call has no effect if Raises_Constraint_Error (N) is True,
-- since there is no point in folding if we have an error.
procedure Fold_Uint (N : Node_Id; Val : Uint; Static : Boolean);
-- Rewrite N with a (N_Integer_Literal, N_Identifier, N_Character_Literal)
-- node as the result of the compile time evaluation of the node N. Val is
-- the result in the integer case and is the position of the literal in the
-- literals list for the enumeration case. Is_Static_Expression is set True
-- in the result node. The result is fully analyzed/resolved. Static
-- indicates whether the result should be considered static or not (True =
-- consider static). The point here is that normally all integer literals
-- are static, but if this was the result of some sequence of evaluation
-- where values were known at compile time but not static, then the result
-- is not static. The call has no effect if Raises_Constraint_Error (N) is
-- True, since there is no point in folding if we have an error.
procedure Fold_Ureal (N : Node_Id; Val : Ureal; Static : Boolean);
-- Rewrite N with a new N_Real_Literal node as the result of the compile
-- time evaluation of the node N. Val is the resulting real value from the
-- folding operation. The Is_Static_Expression flag is set in the result
-- node. The result is fully analyzed and result. Static indicates whether
-- the result should be considered static or not (True = consider static).
-- The point here is that normally all string literals are static, but if
-- this was the result of some sequence of evaluation where values were
-- known at compile time but not static, then the result is not static.
-- The call has no effect if Raises_Constraint_Error (N) is True, since
-- there is no point in folding if we have an error.
procedure Fold (N : Node_Id);
-- Rewrite N with the relevant value if Compile_Time_Known_Value (N) is
-- True, otherwise a no-op.
function Is_In_Range
(N : Node_Id;
Typ : Entity_Id;
Assume_Valid : Boolean := False;
Fixed_Int : Boolean := False;
Int_Real : Boolean := False) return Boolean;
-- Returns True if it can be guaranteed at compile time that expression
-- N is known to be in range of the subtype Typ. A result of False does
-- not mean that the expression is out of range, merely that it cannot be
-- determined at compile time that it is in range. If Typ is a floating
-- point type or Int_Real is set, any integer value is treated as though it
-- was a real value (i.e. the underlying real value is used). In this case
-- we use the corresponding real value, both for the bounds of Typ, and for
-- the value of the expression N. If Typ is a fixed type or a discrete type
-- and Int_Real is False but flag Fixed_Int is True then any fixed-point
-- value is treated as though it was discrete value (i.e. the underlying
-- integer value is used). In this case we use the corresponding integer
-- value, both for the bounds of Typ, and for the value of the expression
-- N. If Typ is a discrete type and Fixed_Int as well as Int_Real are
-- false, integer values are used throughout.
--
-- If Assume_Valid is set True, then N is always assumed to contain a valid
-- value. If Assume_Valid is set False, then N may be invalid (unless there
-- is some independent way of knowing that it is valid, i.e. either it is
-- an entity with Is_Known_Valid set, or Assume_No_Invalid_Values is True.
function Is_Null_Range (Lo : Node_Id; Hi : Node_Id) return Boolean;
-- Returns True if it can guarantee that Lo .. Hi is a null range. If it
-- cannot (because the value of Lo or Hi is not known at compile time) then
-- it returns False.
function Is_OK_Static_Expression (N : Node_Id) return Boolean;
-- An OK static expression is one that is static in the RM definition sense
-- and which does not raise constraint error. For most legality checking
-- purposes you should use Is_Static_Expression. For those legality checks
-- where the expression N should not raise constraint error use this
-- routine. This routine is *not* to be used in contexts where the test is
-- for compile time evaluation purposes. Use Compile_Time_Known_Value
-- instead (see section on "Compile-Time Known Values" above).
function Is_OK_Static_Range (N : Node_Id) return Boolean;
-- Determines if range is static, as defined in RM 4.9(26), and also checks
-- that neither bound of the range raises constraint error, thus ensuring
-- that both bounds of the range are compile-time evaluable (i.e. do not
-- raise constraint error). A result of true means that the bounds are
-- compile time evaluable. A result of false means they are not (either
-- because the range is not static, or because one or the other bound
-- raises CE).
function Is_OK_Static_Subtype (Typ : Entity_Id) return Boolean;
-- Determines whether a subtype fits the definition of an Ada static
-- subtype as given in (RM 4.9(26)) with the additional check that neither
-- bound raises constraint error (meaning that Expr_Value[_R|S] can be used
-- on these bounds).
--
-- This differs from Is_Static_Subtype in that it includes the constraint
-- error checks, which are missing from Is_Static_Subtype.
function Is_Out_Of_Range
(N : Node_Id;
Typ : Entity_Id;
Assume_Valid : Boolean := False;
Fixed_Int : Boolean := False;
Int_Real : Boolean := False) return Boolean;
-- Returns True if it can be guaranteed at compile time that expression is
-- known to be out of range of the subtype Typ. True is returned if Typ is
-- a scalar type, and the value of N can be determined to be outside the
-- range of Typ. A result of False does not mean that the expression is in
-- range, but rather merely that it cannot be determined at compile time
-- that it is out of range. The parameters Assume_Valid, Fixed_Int, and
-- Int_Real are as described for Is_In_Range above.
function Is_Static_Subtype (Typ : Entity_Id) return Boolean;
-- Determines whether a subtype fits the definition of an Ada static
-- subtype as given in (RM 4.9(26)).
--
-- This differs from Is_OK_Static_Subtype (which is what must be used by
-- clients) in that it does not care whether the bounds raise a constraint
-- error exception or not. Used for checking whether expressions are static
-- in the 4.9 sense (without worrying about exceptions).
function Is_Statically_Unevaluated (Expr : Node_Id) return Boolean;
-- This function returns True if the given expression Expr is statically
-- unevaluated, as defined in (RM 4.9 (32.1-32.6)).
function In_Subrange_Of
(T1 : Entity_Id;
T2 : Entity_Id;
Fixed_Int : Boolean := False) return Boolean;
-- Returns True if it can be guaranteed at compile time that the range of
-- values for scalar type T1 are always in the range of scalar type T2. A
-- result of False does not mean that T1 is not in T2's subrange, only that
-- it cannot be determined at compile time. Flag Fixed_Int is used as in
-- routine Is_In_Range above.
function Not_Null_Range (Lo : Node_Id; Hi : Node_Id) return Boolean;
-- Returns True if it can guarantee that Lo .. Hi is not a null range. If
-- it cannot (because the value of Lo or Hi is not known at compile time)
-- then it returns False.
function Predicates_Compatible (T1, T2 : Entity_Id) return Boolean;
-- In Ada 2012, subtypes are statically compatible if the predicates are
-- compatible as well. This function performs the required check that
-- predicates are compatible. Split from Subtypes_Statically_Compatible
-- so that it can be used in specializing error messages.
function Predicates_Match (T1, T2 : Entity_Id) return Boolean;
-- In Ada 2012, subtypes statically match if their predicates match as
-- as well. This function performs the required check that predicates
-- match. Separated out from Subtypes_Statically_Match so that it can
-- be used in specializing error messages.
function Subtypes_Statically_Compatible
(T1 : Entity_Id;
T2 : Entity_Id;
Formal_Derived_Matching : Boolean := False) return Boolean;
-- Returns true if the subtypes are unconstrained or the constraint on
-- on T1 is statically compatible with T2 (as defined by 4.9.1(4)).
-- Otherwise returns false. Formal_Derived_Matching indicates whether
-- the type T1 is a generic actual being checked against ancestor T2
-- in a formal derived type association.
function Subtypes_Statically_Match
(T1 : Entity_Id;
T2 : Entity_Id;
Formal_Derived_Matching : Boolean := False) return Boolean;
-- Determine whether two types T1, T2, which have the same base type,
-- are statically matching subtypes (RM 4.9.1(1-2)). Also includes the
-- extra GNAT rule that object sizes must match (this can be false for
-- types that match in the RM sense because of use of 'Object_Size),
-- except when testing a generic actual T1 against an ancestor T2 in a
-- formal derived type association (indicated by Formal_Derived_Matching).
procedure Test_Comparison
(Op : Node_Id;
Assume_Valid : Boolean;
True_Result : out Boolean;
False_Result : out Boolean);
-- Determine the outcome of evaluating comparison operator Op using routine
-- Compile_Time_Compare. Assume_Valid should be set when the operands are
-- to be assumed valid. Flags True_Result and False_Result are set when the
-- comparison evaluates to True or False respectively.
procedure Why_Not_Static (Expr : Node_Id);
-- This procedure may be called after generating an error message that
-- complains that something is non-static. If it finds good reasons, it
-- generates one or more error messages pointing the appropriate offending
-- component of the expression. If no good reasons can be figured out, then
-- no messages are generated. The expectation here is that the caller has
-- already issued a message complaining that the expression is non-static.
-- Note that this message should be placed using Error_Msg_F or
-- Error_Msg_FE, so that it will sort before any messages placed by this
-- call. Note that it is fine to call Why_Not_Static with something that
-- is not an expression, and usually this has no effect, but in some cases
-- (N_Parameter_Association or N_Range), it makes sense for the internal
-- recursive calls.
--
-- Note that these messages are not continuation messages, instead they are
-- separate unconditional messages, marked with '!'. The reason for this is
-- that they can be posted at a different location from the main message as
-- documented above ("appropriate offending component"), and continuation
-- messages must always point to the same location as the parent message.
procedure Initialize;
-- Initializes the internal data structures
private
-- The Eval routines are all marked inline, since they are called once
pragma Inline (Eval_Actual);
pragma Inline (Eval_Allocator);
pragma Inline (Eval_Character_Literal);
pragma Inline (Eval_If_Expression);
pragma Inline (Eval_Indexed_Component);
pragma Inline (Eval_Named_Integer);
pragma Inline (Eval_Named_Real);
pragma Inline (Eval_Real_Literal);
pragma Inline (Eval_Shift);
pragma Inline (Eval_Slice);
pragma Inline (Eval_String_Literal);
pragma Inline (Eval_Unchecked_Conversion);
pragma Inline (Is_OK_Static_Expression);
end Sem_Eval;