https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118117
Bug ID: 118117
Summary: Array Of Nested Structs Makes Inner Struct Anonymous
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: lgomez at windhoverlabs dot com
Target Milestone: ---
Given the following code
```
#define USE_VIRTUAL
#define USE_ARRAY
struct t1
{
typedef struct
{
} t2;
#ifdef USE_VIRTUAL
virtual void f1();
#endif
};
t1::t2 v1
#ifdef USE_ARRAY
[1]
#endif
;
```
"v1" shows up as anonymous on DWARF:
<source>: file format elf32-littlearm
.debug_info contents:
0x00000000: Compile Unit: length = 0x00000051, format = DWARF32, version =
0x0005, unit_type = DW_UT_compile, abbr_offset = 0x0000, addr_size = 0x04 (next
unit at 0x00000055)
0x0000000c: DW_TAG_compile_unit
DW_AT_producer ("GNU C++17 14.2.0 -mcpu=arm7tdmi
-mfloat-abi=soft -marm -march=armv4t -g")
DW_AT_language (DW_LANG_C_plus_plus_14)
DW_AT_name ("/app/example.cpp")
DW_AT_comp_dir ("/app")
DW_AT_stmt_list (0x00000000)
0x0000001e: DW_TAG_structure_type
DW_AT_name ("t1")
DW_AT_declaration (true)
DW_AT_sibling (0x0000002c)
0x00000026: DW_TAG_structure_type
DW_AT_byte_size (0x01)
DW_AT_decl_file ("/app/example.cpp")
DW_AT_decl_line (3)
DW_AT_decl_column (20)
0x0000002b: NULL
0x0000002c: DW_TAG_array_type
DW_AT_type (0x00000026 "t1::structure ")
DW_AT_sibling (0x0000003c)
0x00000035: DW_TAG_subrange_type
DW_AT_type (0x0000003c "unsigned int")
DW_AT_upper_bound (0x00)
0x0000003b: NULL
0x0000003c: DW_TAG_base_type
DW_AT_byte_size (0x04)
DW_AT_encoding (DW_ATE_unsigned)
DW_AT_name ("unsigned int")
0x00000043: DW_TAG_variable
DW_AT_name ("v1")
DW_AT_decl_file ("/app/example.cpp")
DW_AT_decl_line (10)
DW_AT_decl_column (8)
DW_AT_type (0x0000002c "t1::structure [1]")
DW_AT_external (true)
DW_AT_location (DW_OP_addr 0x0)
0x00000054: NULL
Notice that "v1" points to an array which points to an anonymous struct (a
DW_TAG_structure_type with no DW_AT_name attribute)
If I were to undef "USE_ARRAY" I get the following output:
<source>: file format elf32-littlearm
.debug_info contents:
0x00000000: Compile Unit: length = 0x00000049, format = DWARF32, version =
0x0005, unit_type = DW_UT_compile, abbr_offset = 0x0000, addr_size = 0x04 (next
unit at 0x0000004d)
0x0000000c: DW_TAG_compile_unit
DW_AT_producer ("GNU C++17 14.2.0 -mcpu=arm7tdmi
-mfloat-abi=soft -marm -march=armv4t -g")
DW_AT_language (DW_LANG_C_plus_plus_14)
DW_AT_name ("/app/example.cpp")
DW_AT_comp_dir ("/app")
DW_AT_stmt_list (0x00000000)
0x0000001e: DW_TAG_structure_type
DW_AT_name ("t1")
DW_AT_declaration (true)
DW_AT_sibling (0x0000003b)
0x00000026: DW_TAG_structure_type
DW_AT_byte_size (0x01)
DW_AT_decl_file ("/app/example.cpp")
DW_AT_decl_line (3)
DW_AT_decl_column (20)
DW_AT_linkage_name ("N2t12t2E")
0x0000002f: DW_TAG_typedef
DW_AT_name ("t2")
DW_AT_decl_file ("/app/example.cpp")
DW_AT_decl_line (4)
DW_AT_decl_column (7)
DW_AT_type (0x00000026 "t1::structure ")
0x0000003a: NULL
0x0000003b: DW_TAG_variable
DW_AT_name ("v1")
DW_AT_decl_file ("/app/example.cpp")
DW_AT_decl_line (10)
DW_AT_decl_column (8)
DW_AT_type (0x0000002f "t1::t2")
DW_AT_external (true)
DW_AT_location (DW_OP_addr 0x0)
0x0000004c: NULL
Which is one what one would expect since in source code I can refer to the type
"t1::t2" pretty concretely.
I should point out that this DOES NOT happen in clang x86-64 19.10:
```
<source>: file format elf64-x86-64
.debug_info contents:
0x00000000: Compile Unit: length = 0x00000059, format = DWARF32, version =
0x0004, abbr_offset = 0x0000, addr_size = 0x08 (next unit at 0x0000005d)
0x0000000b: DW_TAG_compile_unit
DW_AT_producer ("clang version 19.1.0
(https://github.com/llvm/llvm-project.git
a4bf6cd7cfb1a1421ba92bca9d017b49936c55e4)")
DW_AT_language (DW_LANG_C_plus_plus_14)
DW_AT_name ("/app/example.cpp")
DW_AT_stmt_list (0x00000000)
DW_AT_comp_dir ("/app")
0x0000001e: DW_TAG_variable
DW_AT_name ("v1")
DW_AT_type (0x00000033 "t1::t2[1]")
DW_AT_external (true)
DW_AT_decl_file ("/app/example.cpp")
DW_AT_decl_line (11)
DW_AT_location (DW_OP_addr 0x0)
0x00000033: DW_TAG_array_type
DW_AT_type (0x00000044 "t1::t2")
0x00000038: DW_TAG_subrange_type
DW_AT_type (0x00000055 "__ARRAY_SIZE_TYPE__")
DW_AT_count (0x01)
0x0000003e: NULL
0x0000003f: DW_TAG_structure_type
DW_AT_name ("t1")
DW_AT_declaration (true)
0x00000044: DW_TAG_typedef
DW_AT_type (0x0000004f "t1::structure ")
DW_AT_name ("t2")
DW_AT_decl_file ("/app/example.cpp")
DW_AT_decl_line (4)
0x0000004f: DW_TAG_structure_type
DW_AT_calling_convention (DW_CC_pass_by_value)
DW_AT_byte_size (0x01)
DW_AT_decl_file ("/app/example.cpp")
DW_AT_decl_line (3)
0x00000054: NULL
0x00000055: DW_TAG_base_type
DW_AT_name ("__ARRAY_SIZE_TYPE__")
DW_AT_byte_size (0x08)
DW_AT_encoding (DW_ATE_unsigned)
0x0000005c: NULL
```
If you want to explore the code:https://godbolt.org/z/n6MfoGhGd
Hope this report was clear and concise.
Thanks
Lorenzo
