test: create clang-like Test shim binary that validates -? options

Author: ErichDonGubler

src/bin/clang-shim.rs

@@ -0,0 +1,102 @@
+//! This bin target is only used for this crate's tests.
+//! It is not intended for users and is not published with the library code to crates.io.
+
+#![cfg_attr(test, allow(dead_code))]
+#![allow(clippy::disallowed_methods)]
+
+use core::hash;
+use std::env;
+use std::fs::File;
+use std::io::{self, prelude::*};
+use std::path::PathBuf;
+use std::process::ExitCode;
+
+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)),
+    );
+
+    let mut passed_cli_validation = true;
+
+    // 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 {
+            eprintln!(
+                "Found `-?` argument, but it was not preceded by a `--driver-mode=cl` argument."
+            );
+        }
+        passed_cli_validation &= has_cl_clang_driver_before_cl_like_help_option;
+    }
+
+    // Find the first nonexistent candidate file to which the program's args can be written.
+    let candidate = (0..).find_map(|i| {
+        let candidate = out_dir.join(format!("out{}", i));
+
+        if candidate.exists() {
+            // If the file exists, commands have already run. Try again.
+            None
+        } else {
+            Some(candidate)
+        }
+    }).unwrap_or_else(|| panic!("Cannot find the first nonexistent candidate file to which the program's args can be written under out_dir '{}'", out_dir.display()));
+
+    // Create a file and record the args passed to the command.
+    let f = File::create(&candidate).unwrap_or_else(|e| {
+        panic!(
+            "{}: can't create candidate: {}, error: {}",
+            program,
+            candidate.display(),
+            e
+        )
+    });
+    let mut f = io::BufWriter::new(f);
+
+    (|| {
+        for arg in args {
+            writeln!(f, "{}", arg)?;
+        }
+
+        f.flush()?;
+
+        let mut f = f.into_inner()?;
+        f.flush()?;
+        f.sync_all()
+    })()
+    .unwrap_or_else(|e| {
+        panic!(
+            "{}: can't write to candidate: {}, error: {}",
+            program,
+            candidate.display(),
+            e
+        )
+    });
+
+    // Create a file used by some tests.
+    let path = &out_dir.join("libfoo.a");
+    File::create(path).unwrap_or_else(|e| {
+        panic!(
+            "{}: can't create libfoo.a: {}, error: {}",
+            program,
+            path.display(),
+            e
+        )
+    });
+
+    if passed_cli_validation {
+        ExitCode::SUCCESS
+    } else {
+        ExitCode::FAILURE
+    }
+}

tests/support/mod.rs

@@ -67,7 +67,9 @@ impl Test {
     }
 
     pub fn clang() -> Test {
-        let t = Test::new();
+        let mut t = Test::new();
+        t.gcc.pop();
+        t.gcc.push(format!("clang-shim{}", env::consts::EXE_SUFFIX));
         t.shim("clang").shim("clang++").shim("ar");
         t
     }