Alexandre Ganea 27ebc844f5 [clang][CodeView] Prevent the input name from appearing in LF_BUILDINFO (#194140) ...

The implicit contract of an `LF_BUILDINFO` record (represented in LLVM
by
[`BuildInfoRecord`](6f0b55ec55/llvm/include/llvm/DebugInfo/CodeView/TypeRecord.h (L667)))
is that its `CommandLine` field should not contain the input source file
— a separate `SourceFile` field is reserved for that.

When the command-line flattening was moved from `llvm/` to `clang/` in
#106369, the comparison value used to identify and strip the source
positional was switched from `MainSourceFile->getFilename()` (the full
input path resolved by clang) to `CodeGenOpts.MainFileName` (just the
basename, set via `-main-file-name`). As a result, when the driver is
invoked with an absolute source path the cc1 positional is that absolute
path and no longer matches `MainFileName`, so the source filename leaks
into `CommandLine` as a trailing positional cc1 argument.

This is a regression in Clang 20. It breaks downstream tooling such as
Live++, whose unity-splitting feature relies on the embedded command
line being the cc1 invocation minus the source. Reported in #193900.

This PR restores the previous behavior by passing the resolved frontend
input path(s) to `flattenClangCommandLine` and including them in the
equality check that strips the source positional. The basename match
against `MainFileName` is kept for the relative-input case. A regression
test (and a symmetric relative-path test) is added to
`clang/test/DebugInfo/Generic/codeview-buildinfo.c`.

Should fix #193900.

2026-04-27 07:21:49 -04:00

63 KiB

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