Path map tool paths in compilation actions

This is required for toolchains where tools are generated files, e.g. wrappers around compilers.

Closes #25035.

PiperOrigin-RevId: 719209649
Change-Id: Iaa10a066bf271ffb485d25f38f8db87a020144c6

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

@@ -94,7 +94,13 @@ List<String> getArguments(
     List<String> commandLine = new ArrayList<>();
 
     // first: The command name.
-    commandLine.add(getToolPath());
+    if (pathMapper.isNoop()) {
+      commandLine.add(getToolPath());
+    } else {
+      // getToolPath() ultimately returns a PathFragment's getSafePathString(), so its safe to
+      // reparse it here with no risk of e.g. altering a user-specified absolute path.
+      commandLine.add(pathMapper.map(PathFragment.create(getToolPath())).getSafePathString());
+    }
 
     // second: The compiler options.
     if (parameterFilePath != null) {