Description of the bug:

On macOS, the treat_warnings_as_errors feature doesn't work because the linker flag is wrong (-fatal-warnings instead of -fatal_warnings).

Which category does this issue belong to?

No response

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

Create a trivial workspace with BUILD:

cc_binary(
    name = "bin",
    srcs = ["bin.cc"],
    features = ["treat_warnings_as_errors"],
)

and bin.cc:

int main() {}

Then bazel build //:bin will fail on macOS with Bazel 7.

Which operating system are you running Bazel on?

macOS

What is the output of bazel info release?

release 7.0.0

If bazel info release returns development version or (@non-git), tell us how you built Bazel.

N/A

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

N/A

Is this a regression? If yes, please try to identify the Bazel commit where the bug was introduced.

I don't think it's a regression

Have you found anything relevant by searching the web?

no

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

Output of bazel build --verbose_failures :all:

[...]
ERROR: /private/tmp/warn/BUILD:1:10: Linking bin failed: (Exit 1): cc_wrapper.sh failed: error executing CppLink command (from target //:bin) 
[...]
external/bazel_tools~cc_configure_extension~local_config_cc/cc_wrapper.sh @bazel-out/darwin_arm64-fastbuild/bin/bin-2.params
[...]
ld: unknown options: -fatal-warnings 
clang: error: linker command failed with exit code 1 (use -v to see invocation)
Target //:bin failed to build

The linker params file contains

-o
bazel-out/darwin_arm64-fastbuild/bin/bin
bazel-out/darwin_arm64-fastbuild/bin/_objs/bin/bin.o
-Wl,-S
-mmacos-version-min=14.2
-no-canonical-prefixes
-fobjc-link-runtime
-headerpad_max_install_names
-lc++
-lm
-Wl,-fatal-warnings

man ld says the correct option would be -fatal_warnings (note the underscore).