[gdb/testsuite] Fix gdb.dwarf2/enum-type-c++.exp with clang

When running test-case gdb.dwarf2/enum-type-c++.exp with clang, we get:
...
FAIL: gdb.dwarf2/enum-type-c++.exp: val1 has a parent
FAIL: gdb.dwarf2/enum-type-c++.exp: print ns::A::val1
FAIL: gdb.dwarf2/enum-type-c++.exp: val2 has correct parent
FAIL: gdb.dwarf2/enum-type-c++.exp: print ns::ec::val2
...

The problem is that the debug info produced by clang does not contain any
references to enumerators val1 and val2, or the corresponding enumeration
types.

Instead, the variables u1 and u2 are considered to be simply of type int:
...
 <1><fb>: Abbrev Number: 2 (DW_TAG_variable)
    <fc>   DW_AT_name        : u1
    <fd>   DW_AT_type        : <0x106>
    <101>   DW_AT_external    : 1
    <103>   DW_AT_location    : (DW_OP_addrx <0>)
 <1><106>: Abbrev Number: 3 (DW_TAG_base_type)
    <107>   DW_AT_name        : int
    <108>   DW_AT_encoding    : 5       (signed)
    <109>   DW_AT_byte_size   : 4
 <1><10a>: Abbrev Number: 2 (DW_TAG_variable)
    <10b>   DW_AT_name        : u2
    <10c>   DW_AT_type        : <0x106>
    <110>   DW_AT_external    : 1
    <112>   DW_AT_location    : (DW_OP_addrx <0x1>)
...

Fix this by checking whether val1 and val2 are present in the cooked index
before checking whether they have the correct parent.

This cannot be expressed efficiently with gdb_test_lines, so factor out
gdb_get_lines and use that instead.

The test-case still calls "maint print objfiles" twice, but the first time is
for have_index.  We should probably use a gdb_caching_proc for this.

Tested on aarch64-linux.

Reported-By: Guinevere Larsen <guinevere@redhat.com>
Reviewed-By: Keith Seitz <keiths@redhat.com>
Tested-By: Guinevere Larsen <guinevere@redhat.com>
2 files changed