Wrong/missing debuginfo for struct with default constructor and nested struct declaration

[m-mueller678]

#include<cstdlib>

struct A  {
    int x;

    A(){};

    struct Inner {
        int inner_inner = 0;
    };

    Inner inner;  // exclusive
};

int main(){
    A* a=reinterpret_cast<A*>(malloc(sizeof(A)));
    a->x=0;
}

Compiling this with clang and debugging with either gdb or lldb, A is reported as incomplete type or as 'no such type' depending on situation.
clang++-17 sample.cpp -g -std=c++20 && gdb a.out -ex 'ptype A'

GNU gdb (Ubuntu 12.1-0ubuntu1~22.04) 12.1
Copyright (C) 2022 Free Software Foundation, Inc.
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Reading symbols from a.out...
No symbol "A" in current context.
(gdb) 

If the constructor is removed, it works as expected.

tested with both of these:

Ubuntu clang version 17.0.6 (++20231209124227+6009708b4367-1~exp1~20231209124336.77)
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin

Ubuntu clang version 15.0.7
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin

[llvmbot]

@llvm/issue-subscribers-clang-codegen

Author: None (m-mueller678)

Details

``` #include<cstdlib>

struct A {
int x;

A(){};

struct Inner {
    int inner_inner = 0;
};

Inner inner;  // exclusive

};

int main(){
A* a=reinterpret_cast<A*>(malloc(sizeof(A)));
a->x=0;
}

Compiling this with clang and debugging with either gdb or lldb, A is reported as incomplete type or as 'no such type' depending on situation.
`clang++-17 sample.cpp -g -std=c++20 && gdb a.out -ex 'ptype A'`

GNU gdb (Ubuntu 12.1-0ubuntu1~22.04) 12.1
Copyright (C) 2022 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Type "show copying" and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<https://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.

For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from a.out...
No symbol "A" in current context.
(gdb)

If the constructor is removed, it works as expected.

tested with both of these:

Ubuntu clang version 17.0.6 (++20231209124227+6009708b4367-1exp120231209124336.77)
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin

Ubuntu clang version 15.0.7
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin

</details>

[EugeneZelenko]

Could you please try 18 or main branch?

[m-mueller678]

Will "Install (qualification branch)" from llvm.org work?

[eoineoineoin]

I've encountered something very similar without the need for a nested struct. Tested with the latest (530d4c9) git build

struct Incomplete
{
    Incomplete() { set(0); }
    void set(int a) { VeryImportantField = a; }
    int VeryImportantField;
};

int main()
{
    char buffer[1024];
    Incomplete* bla = (Incomplete*)buffer;
    bla->set(0x1234);
    return 0;
}

Compiling and testing with clang:

eoin@eoinlz40~/incompletetypes $ ~/code/llvm-project/build/bin/clang++ -ggdb bla.cpp -o a.out-clang && gdb a.out-clang -ex 'ptype Incomplete'
Reading symbols from a.out-clang...
No symbol "Incomplete" in current context.
(gdb) quit

Compared to compiling with gcc:

eoin@eoinlz40~/incompletetypes $ g++ -ggdb ./bla.cpp -o a.out-g++ && gdb a.out-g++ -ex 'ptype Incomplete'
Reading symbols from a.out-g++...
type = struct Incomplete {
    int VeryImportantField;
  public:
    Incomplete(void);
    void set(int);
}
(gdb) quit

Using lvm-dwarfdump on the gcc executable, I see an entry for VeryImportantField:

0x00000070:     DW_TAG_member
                  DW_AT_name	("VeryImportantField")
                  DW_AT_decl_file	("/home/eoin/incompletetypes/./bla.cpp")
                  DW_AT_decl_line	(5)
                  DW_AT_decl_column	(9)
                  DW_AT_type	(0x00000089 "int")
                  DW_AT_data_member_location	(0x00)

But this information is not existent in the llvm executable.

Seems to be caused by the inlined constructor, despite not being called in this repro. If the constructor of Incomplete is omitted, or if it's not declared as implicitly inline, then llvm does emit the debug info.