[lld] [llvm] [DTLTO][LLD][ELF] Support bitcode members of thin archives (PR #149425)

[Fangrui Song via llvm-commits]

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@@ -0,0 +1,97 @@
+REQUIRES: ld.lld,llvm-ar
+
+## Test that a DTLTO link succeeds and outputs the expected set of files
+## correctly when thin archives are present.
+
+RUN: rm -rf %t && split-file %s %t && cd %t
+
+## Compile bitcode. -O2 is required for cross-module importing.
+RUN: %clang -O2 --target=x86_64-linux-gnu -flto=thin -c \
+RUN:   foo.c bar.c dog.c cat.c start.c
+
+## Generate thin archives.
+RUN: llvm-ar rcs foo.a foo.o --thin
+## Create this bitcode thin archive in a subdirectory to test the expansion of
+## the path to a bitcode file that is referenced using "..", e.g., in this case
+## "../bar.o".
+RUN: mkdir lib
+RUN: llvm-ar rcs lib/bar.a bar.o --thin
+## Create this bitcode thin archive with an absolute path entry containing "..".
+RUN: llvm-ar rcs dog.a %t/lib/../dog.o --thin
+## The bitcode member of cat.a will not be used in the link.
+RUN: llvm-ar rcs cat.a cat.o --thin
+RUN: llvm-ar rcs start.a start.o --thin
+
+## Link from a different directory to ensure that thin archive member paths are
+## resolved correctly relative to the archive locations.
+RUN: mkdir %t/out && cd %t/out
+
+RUN: %clang --target=x86_64-linux-gnu -flto=thin -fuse-ld=lld %t/foo.a %t/lib/bar.a ../start.a %t/cat.a \
+RUN:   -Wl,--whole-archive ../dog.a \
+RUN:   -fthinlto-distributor=%python \
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MaskRay wrote:

does %python need quoting?

https://github.com/llvm/llvm-project/pull/149425