[PATCH] D93023: Replace deprecated %T in 2 tests.

[Hafiz Abid Qadeer via Phabricator via cfe-commits]

abidh added a comment.

It seems that testcase I added has brought to surface a hidden issue. If you
look at the end of Generic_GCC::GCCInstallationDetector::AddDefaultGCCPrefixes,
it adds sysroot/usr to the Prefixes. If the sysroot is empty, this will end up
using the toolchain that you installed in /usr.

This code path is only taken if --gcc-toolchain is empty (or not given). The
mips-reduced-toolchain.cpp is a good example as testcase is dependent on this
behavior. If user provides a non-empty gcc-toolchain path, even if that path is
non-existent, this code path is not taken. This is why riscv32-toolchain-extra.c
did not fail before because it used an invalid path and not empty path for
--gcc-toolchain.

As a result of this behavior, if the user of RISCVToolChain does not provide a
--gcc-toolchain, what happens is dependent of whether user had a riscv
toolchain in /usr directory.

1. If a toolchain was present then clang will pick it
2. Otherwise clang will try clang_dir/../ (see RISCVToolChain::computeSysRoot())

For cross toolchains, this seems fragile to me. In this case, clang is picking
runtime bits from a riscv64-linux-gnu for riscv32/64-unknown-elf target. This
may cause difficult to debug problem.

I would wait for users of RISCVToolChain to comment if this is expected behavior.
If yes then I can probably update the test on the pattern of mips-reduced-toolchain.cpp.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D93023/new/

https://reviews.llvm.org/D93023