Fix runtime_solib_name for --incompatible_macos_set_install_name

The `runtime_solib_name` link variable had an incorrect value in the case of a transitive dynamic library. Since non-transitive ("nodeps") dynamic libraries are no longer used on macOS, the `--incompatible_macos_set_install_name` flag didn't have any positive effect.

This PR is intentionally limited to the fix so that it can be cherry-picked into Bazel 7, where it can make the incompatible flag work with the `apple_support` toolchain. A follow-up PR will add the feature to the Unix toolchain and flip the incompatible flag for Bazel 8.

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

@@ -852,7 +852,7 @@ public CppLinkAction build() throws EvalException, InterruptedException {
             output.getExecPathString(),
             SolibSymlinkAction.getDynamicLibrarySoname(
                 output.getRootRelativePath(),
-                /* preserveName= */ false,
+                /* preserveName= */ linkType != LinkTargetType.NODEPS_DYNAMIC_LIBRARY,
                 linkActionConstruction.getContext().getConfiguration().getMnemonic()),
             thinltoParamFile != null ? thinltoParamFile.getExecPathString() : null,
             toolchain,

src/test/shell/bazel/BUILD

@@ -128,6 +128,7 @@ sh_test(
     ],
     tags = [
         "no_windows",  # darwin-specific test
+        "requires-network",  # For Bzlmod
     ],
 )
 

src/test/shell/bazel/cpp_darwin_integration_test.sh

@@ -139,6 +139,8 @@ EOF
   return 0
 }
 
+# TODO: This test passes vacuously as the default Unix toolchain doesn't use
+# the set_install_name feature yet.
 function test_cc_test_with_explicit_install_name() {
   mkdir -p cpp
   cat > cpp/BUILD <<EOF
@@ -147,10 +149,61 @@ cc_library(
   srcs = ["foo.cc"],
   hdrs = ["foo.h"],
 )
+cc_shared_library(
+  name = "foo_shared",
+  deps = [":foo"],
+)
+cc_test(
+  name = "test",
+  srcs = ["test.cc"],
+  deps = [":foo"],
+  dynamic_deps = [":foo_shared"],
+)
+EOF
+  cat > cpp/foo.h <<EOF
+  int foo();
+EOF
+  cat > cpp/foo.cc <<EOF
+  int foo() { return 0; }
+EOF
+  cat > cpp/test.cc <<EOF
+  #include "cpp/foo.h"
+  int main() {
+    return foo();
+  }
+EOF
+
+  bazel test --incompatible_macos_set_install_name //cpp:test || \
+      fail "bazel test //cpp:test failed"
+  # Ensure @rpath is correctly set in the binary.
+  ./bazel-bin/cpp/test || \
+      fail "//cpp:test workspace execution failed, expected return 0, got $?"
+  cd bazel-bin
+  ./cpp/test || \
+      fail "//cpp:test execution failed, expected 0, but $?"
+}
+
+function test_cc_test_with_explicit_install_name_apple_support() {
+  cat > MODULE.bazel <<EOF
+bazel_dep(name = "apple_support", version = "1.16.0")
+EOF
+
+  mkdir -p cpp
+  cat > cpp/BUILD <<EOF
+cc_library(
+  name = "foo",
+  srcs = ["foo.cc"],
+  hdrs = ["foo.h"],
+)
+cc_shared_library(
+  name = "foo_shared",
+  deps = [":foo"],
+)
 cc_test(
   name = "test",
   srcs = ["test.cc"],
   deps = [":foo"],
+  dynamic_deps = [":foo_shared"],
 )
 EOF
   cat > cpp/foo.h <<EOF