[PATCH] D31011: recommend using llvm-ar when finding undefined references and empty archives

[Bob Haarman via Phabricator via llvm-commits]

inglorion created this revision.

When we perform LTO builds with a version of ar that does not
understand LLVM bitcode objects, we end up with undefined references,
because our archive files do not list the bitcode symbols in their
indices. The error messages do not make it clear what the real problem
is. This change adds a note that points out the likely problem and
solution. It is similar in spirit to r282633, but aims to avoid false
positives by only triggering when we see both undefined references and
archives without symbols in their indices.

Fixes PR32281.


https://reviews.llvm.org/D31011

Files:
  ELF/Driver.cpp
  ELF/Error.cpp
  ELF/Error.h
  ELF/InputFiles.cpp
  ELF/InputFiles.h
  ELF/Relocations.cpp
  test/ELF/lto/archive-no-index.ll

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