test: ensure clang --driver-mode=cl is MSVC- and clang-cl-like (#1381)

Author: ErichDonGubler

src/bin/gcc-shim.rs renamed to src/bin/cc-shim.rs

@@ -8,14 +8,16 @@ use std::env;
 use std::fs::File;
 use std::io::{self, prelude::*};
 use std::path::PathBuf;
+use std::process::ExitCode;
 
-fn main() {
-    let mut args = env::args();
+fn main() -> ExitCode {
+    let args = env::args().collect::<Vec<_>>();
+    let mut args = args.iter();
     let program = args.next().expect("Unexpected empty args");
 
     let out_dir = PathBuf::from(
-        env::var_os("GCCTEST_OUT_DIR")
-            .unwrap_or_else(|| panic!("{}: GCCTEST_OUT_DIR not found", program)),
+        env::var_os("CC_SHIM_OUT_DIR")
+            .unwrap_or_else(|| panic!("{}: CC_SHIM_OUT_DIR not found", program)),
     );
 
     // Find the first nonexistent candidate file to which the program's args can be written.
@@ -42,7 +44,7 @@ fn main() {
     let mut f = io::BufWriter::new(f);
 
     (|| {
-        for arg in args {
+        for arg in args.clone() {
             writeln!(f, "{}", arg)?;
         }
 
@@ -61,6 +63,27 @@ fn main() {
         )
     });
 
+    if program.starts_with("clang") {
+        // Validate that we got no `-?` without a preceding `--driver-mode=cl`. Compiler family
+        // detection depends on this.
+        if let Some(cl_like_help_option_idx) = args.clone().position(|a| a == "-?") {
+            let has_cl_clang_driver_before_cl_like_help_option = args
+                .clone()
+                .take(cl_like_help_option_idx)
+                .rev()
+                .find_map(|a| a.strip_prefix("--driver-mode="))
+                .is_some_and(|a| a == "cl");
+            if has_cl_clang_driver_before_cl_like_help_option {
+                return ExitCode::SUCCESS;
+            } else {
+                eprintln!(
+                    "Found `-?` argument, but it was not preceded by a `--driver-mode=cl` argument."
+                );
+                return ExitCode::FAILURE;
+            }
+        }
+    }
+
     // Create a file used by some tests.
     let path = &out_dir.join("libfoo.a");
     File::create(path).unwrap_or_else(|e| {
@@ -71,4 +94,6 @@ fn main() {
             e
         )
     });
+
+    ExitCode::SUCCESS
 }

tests/cc_env.rs

@@ -15,6 +15,7 @@ fn main() {
     extra_flags();
     path_to_ccache();
     more_spaces();
+    clang_cl();
 }
 
 fn ccache() {
@@ -110,3 +111,18 @@ fn more_spaces() {
     let compiler = test.gcc().file("foo.c").get_compiler();
     assert_eq!(compiler.path(), Path::new("cc"));
 }
+
+fn clang_cl() {
+    for exe_suffix in ["", ".exe"] {
+        let test = Test::clang();
+        let bin = format!("clang{exe_suffix}");
+        env::set_var("CC", &format!("{bin} --driver-mode=cl"));
+        let test_compiler = |build: cc::Build| {
+            let compiler = build.get_compiler();
+            assert_eq!(compiler.path(), Path::new(&*bin));
+            assert!(compiler.is_like_msvc());
+            assert!(compiler.is_like_clang_cl());
+        };
+        test_compiler(test.gcc());
+    }
+}

tests/support/mod.rs

@@ -44,8 +44,11 @@ impl Test {
         if gcc.ends_with("deps") {
             gcc.pop();
         }
-        let td = Builder::new().prefix("gcc-test").tempdir_in(&gcc).unwrap();
-        gcc.push(format!("gcc-shim{}", env::consts::EXE_SUFFIX));
+        let td = Builder::new()
+            .prefix("cc-shim-test")
+            .tempdir_in(&gcc)
+            .unwrap();
+        gcc.push(format!("cc-shim{}", env::consts::EXE_SUFFIX));
         Test {
             td,
             gcc,
@@ -98,7 +101,7 @@ impl Test {
             .debug(false)
             .out_dir(self.td.path())
             .__set_env("PATH", self.path())
-            .__set_env("GCCTEST_OUT_DIR", self.td.path());
+            .__set_env("CC_SHIM_OUT_DIR", self.td.path());
         if self.msvc {
             cfg.compiler(self.td.path().join("cl"));
             cfg.archiver(self.td.path().join("lib.exe"));