Thanks for working on this!

Unrelated to this PR, but while trying to test this PR I noticed that with DWARFv5 anonymous sources get invalid file names. They are supposed to be called <anon>, but get called /path/to/working_directory/<anon> instead by gdb. By the way do you know of any debugger that already supports this? Even the gdb of Fedora Rawhide doesn't seem to support it.

Unrelated to this PR, but while trying to test this PR I noticed that with DWARFv5 anonymous sources get invalid file names. They are supposed to be called <anon>, but get called /path/to/working_directory/<anon> instead by gdb.

The fix might be FileName::prefer_remapped_unconditionally - internal files and all that.

How do you check the output? With what RUSTFLAGS do you compile a binary? Can you give me a repro?

I used dist/rustc-clif -g -Zdwarf-version=5 -Zembed-source foo.rs and then removing foo.rs for trying to test -Zembed-source.

echo 'fn main() {}' | dist/rustc-clif -g -Zdwarf-version=5 - reproduces the <anon> issue.

both GDB and LLDB seem to not have DWARFv5 embedded source support :/

When using

echo 'fn main() {}' | ./dist/rustc-clif -g -Zdwarf-version=5 - 2>&1
echo 'int main() { return 0; }' | gcc -x c -gdwarf-5 - -o gcc_test

echo "y" | gdb -batch -ex "file rust_out" -ex "b main" -ex "list" 2>&1 | tail -1`
echo "y" | gdb -batch -ex "file gcc_test" -ex "b main" -ex "list" 2>&1 | tail -1

(after the latest change) I get:

warning: 1      <anon>: No such file or directory
warning: 1      <stdin>: No such file or directory

which looks okay!

which looks okay!

I really hate this solution, though, and I think it should be reverted - I can't seem to find a better approach here.

This is what cg_llvm does for determining the file name: https://github.com/rust-lang/rust/blob/caccb4d0368bd918ef6668af8e13834d07040417/compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs#L552-L648 It should be lifted into cg_ssa at some point, but for now what you have LGTM. Thanks!