cc_binary's linkopts should expand labels used with "-Wl,"

[pmuetschard]

Description of the problem / feature request:

Passing options to the linker requires -Wl,<option>. To pass an option with a value, one can do one of the following:

• -Wl,<option> -Wl,<value>
• -Wl,<option>=<value>
• -Wl,<option>,<value>

Bazel's cc_binary rule, however, only expands labels in the linkopts field if the string "does not start with $ or -". This makes it impossible to pass a file that is a label as a value to a link option.

For example, to pass a linker version script, one would need to cause the following flag passed to gcc:
-Wl,--version-script,<script>
However this is impossible:
linkopts = ["-Wl,--version-script,", "script.ldscript"] although performing label expansion, passes the script.ldscript file as a separate argument, which gets ignored.
linkopts = ["-Wl,--version-script", "-Wl,script.ldscript"] doesn't do label expansion, nor does it if using any of the other formats, and $(location script.ldscript) is not allowed.

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

cc_binary(
  ...
  deps = [..., "script.ldscript"],
  linkopts = ["-Wl,--version-script,script.ldscript"]
  ...
)

What operating system are you running Bazel on?

Linux, but this is likely present on all OSs.

What's the output of bazel info release?

0.9.0, but also TOTT

[pmuetschard]

Oops, never mind ["-Wl,--version-script,", "script.ldscript"] actually works. Sorry about that.