Bazel hardcodes passing -static-libgcc even if you don't use libgcc

[dapirian]

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Description of the problem / feature request:

Bazel hardcodes passing -static-libgcc even if you compile with -rtlib=compiler-rt. This doesn't particularly hurt anything, but it causes warnings to be spammed:
clang: warning: argument unused during compilation: '-static-libgcc' [-Wunused-command-line-argument]

Looks like this happens here:

bazel/src/main/java/com/google/devtools/build/lib/rules/cpp/CcBinary.java

Line 329 in aaba6fe

linkActionBuilder.addLinkopt("-static-libgcc");

This should be configurable somewhere toolchain/crosstool related.

Feature requests: what underlying problem are you trying to solve with this feature?

Trying to use compiler-rt with bazel

Bugs: what's the simplest, easiest way to reproduce this bug? Please provide a minimal example if possible.

Build with clang and pass -rtlib=compiler-rt

What operating system are you running Bazel on?

Ubuntu 14.04

What's the output of bazel info release?

release 0.16.0

What's the output of git remote get-url origin ; git rev-parse master ; git rev-parse HEAD ?

Not a public repo

Have you found anything relevant by searching the web?

No

Any other information, logs, or outputs that you want to share?

No

[benjaminp]

You can pass --experimental_dont_emit_static_libgcc to inhibit that.