Bug 1943149 - build(swgl): work around broken (upstream) cc::Tool detection of clang --driver-mode=cl r=#gfx-reviewers

In upstream, a new heuristic for detecting compiler families in
`cc::Tool` was introduced. The heuristic we originally patched upstream
is now the fallback heuristic, and does not get used for our `clang`
compiler. This causes our interaction with default flags and
`cc::Tool::is_like_msvc` to be incorrect in `swgl`, since `clang`'s CLI
to use `cl`-like arguments, and rejects `clang`-like arguments.

Work around this by detecting checking `Tool`s' base command and
"wrapper arguments" to see if we're (1) using `clang` and (2) we have
a wrapper argument matching `--driver-mode=cl`. If so, provide `cl`-like
arguments in `swgl`, rather than `clang`-like arguments.

Author: ErichDonGubler

gfx/wr/swgl/build.rs

@@ -116,7 +116,7 @@ fn translate_shader(
     let mut build = cc::Build::new();
     build.no_default_flags(true);
     if let Ok(tool) = build.try_get_compiler() {
-        if tool.is_like_msvc() {
+        if is_like_msvc(&tool) {
             build.flag("/EP");
             if tool.path().to_str().is_some_and(|p| p.contains("clang")) {
                 build.flag("/clang:-undef");
@@ -185,7 +185,7 @@ fn main() {
     build.cpp(true);
 
     if let Ok(tool) = build.try_get_compiler() {
-        if tool.is_like_msvc() {
+        if is_like_msvc(&tool) {
             build
                 .flag("/std:c++17")
                 .flag("/EHs-")
@@ -212,7 +212,7 @@ fn main() {
         // instructions makes things easier on the processor and in places where it matters we can
         // probably explicitly use reciprocal instructions and avoid the refinement step.
         // Also, allow checks for non-finite values which fast-math may disable.
-        if tool.is_like_msvc() {
+        if is_like_msvc(&tool) {
             build
                 .flag("/fp:fast")
                 .flag("-Xclang")
@@ -252,3 +252,20 @@ impl Drop for EnvVarGuard {
         }
     }
 }
+
+fn is_like_msvc(tool: &cc::Tool) -> bool {
+    tool.is_like_msvc() || {
+        tool.is_like_clang()
+            && tool.to_command().get_args().any(|arg| {
+                // `mozilla-central` does this funky thing where it replaces `clang-cl.exe` with
+                // `clang.exe --driver-mode=cl`, which isn't considered by `Tool::is_like_msvc`, _but_
+                // it forces the CLI to adhere to a `cl`-like interface and reject naively `clang`-like
+                // arguments.
+                //
+                // See also `config/static-checking-config.mk`:
+                // <https://searchfox.org/mozilla-central/rev/dd8b64a6198ff599a5eb2ca096845ebd6997457f/config/static-checking-config.mk>
+                arg.to_str()
+                    .is_some_and(|a| a.starts_with("--driver-mode=cl"))
+            })
+    }
+}