Rewrite no-input-file.stderr test in Rust and support diff

Cargo.lock

@@ -3343,6 +3343,7 @@ version = "0.0.0"
 dependencies = [
  "object 0.34.0",
  "regex",
+ "similar",
  "wasmparser",
 ]
 
@@ -5138,6 +5139,12 @@ version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0fda2ff0d084019ba4d7c6f371c95d8fd75ce3524c3cb8fb653a3023f6323e64"
 
+[[package]]
+name = "similar"
+version = "2.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fa42c91313f1d05da9b26f267f931cf178d4aba455b4c4622dd7355eb80c6640"
+
 [[package]]
 name = "siphasher"
 version = "0.3.11"

src/tools/run-make-support/Cargo.toml

@@ -5,5 +5,6 @@ edition = "2021"
 
 [dependencies]
 object = "0.34.0"
+similar = "2.5.0"
 wasmparser = "0.118.2"
 regex = "1.8" # 1.8 to avoid memchr 2.6.0, as 2.5.0 is pinned in the workspace

src/tools/run-make-support/src/diff/mod.rs

@@ -0,0 +1,64 @@
+use similar::TextDiff;
+use std::path::Path;
+
+#[cfg(test)]
+mod tests;
+
+pub fn diff() -> Diff {
+    Diff::new()
+}
+
+#[derive(Debug)]
+pub struct Diff {
+    expected: Option<String>,
+    actual: Option<String>,
+}
+
+impl Diff {
+    /// Construct a bare `diff` invocation.
+    pub fn new() -> Self {
+        Self { expected: None, actual: None }
+    }
+
+    /// Specify the expected output for the diff from a file.
+    pub fn expected_file<P: AsRef<Path>>(&mut self, path: P) -> &mut Self {
+        let content = std::fs::read_to_string(path).expect("failed to read file");
+        self.expected = Some(content);
+        self
+    }
+
+    /// Specify the expected output for the diff from a given text string.
+    pub fn expected_text<T: AsRef<[u8]>>(&mut self, text: T) -> &mut Self {
+        self.expected = Some(String::from_utf8_lossy(text.as_ref()).to_string());
+        self
+    }
+
+    /// Specify the actual output for the diff from a file.
+    pub fn actual_file<P: AsRef<Path>>(&mut self, path: P) -> &mut Self {
+        let content = std::fs::read_to_string(path).expect("failed to read file");
+        self.actual = Some(content);
+        self
+    }
+
+    /// Specify the actual output for the diff from a given text string.
+    pub fn actual_text<T: AsRef<[u8]>>(&mut self, text: T) -> &mut Self {
+        self.actual = Some(String::from_utf8_lossy(text.as_ref()).to_string());
+        self
+    }
+
+    /// Executes the diff process, prints any differences to the standard error.
+    pub fn run(&self) {
+        let output = self.do_run();
+        if !output.is_empty() {
+            panic!("{}", output)
+        }
+    }
+
+    /// Compares the expected and actual texts and generates a diff output as a string.
+    fn do_run(&self) -> String {
+        let expected = self.expected.as_ref().expect("expected text not set");
+        let actual = self.actual.as_ref().expect("actual text not set");
+
+        TextDiff::from_lines(expected, actual).unified_diff().header("expect", "actual").to_string()
+    }
+}

src/tools/run-make-support/src/diff/tests.rs

@@ -0,0 +1,38 @@
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_diff() {
+        let expected = "foo\nbar\nbaz\n";
+        let actual = "foo\nbar\nbaz\n";
+        diff().expected_text(expected).actual_text(actual).run();
+    }
+
+    #[test]
+    #[should_panic]
+    fn test_do_run() {
+        let expected = "foo\nbar\nbaz\n";
+        let actual = "foo\nbar\nqux\n";
+        diff().expected_text(expected).actual_text(actual).run();
+    }
+
+    #[test]
+    fn test_do_run_fail() {
+        let expected = "foo\nbar\nbaz\n";
+        let actual = "foo\nbaz\nbar\n";
+        let output = diff().expected_text(expected).actual_text(actual).do_run();
+
+        assert_eq!(
+            output,
+            r#"--- expect
++++ actual
+@@ -1,3 +1,3 @@
+ foo
++baz
+ bar
+-baz
+"#,
+        );
+    }
+}

src/tools/run-make-support/src/lib.rs

@@ -5,6 +5,7 @@
 
 pub mod cc;
 pub mod clang;
+pub mod diff;
 pub mod llvm_readobj;
 pub mod run;
 pub mod rustc;
@@ -20,6 +21,7 @@ pub use wasmparser;
 
 pub use cc::{cc, extra_c_flags, extra_cxx_flags, Cc};
 pub use clang::{clang, Clang};
+pub use diff::{diff, Diff};
 pub use llvm_readobj::{llvm_readobj, LlvmReadobj};
 pub use run::{run, run_fail};
 pub use rustc::{aux_build, rustc, Rustc};

src/tools/tidy/src/allowed_run_make_makefiles.txt

@@ -189,7 +189,6 @@ run-make/no-builtins-attribute/Makefile
 run-make/no-builtins-lto/Makefile
 run-make/no-cdylib-as-rdylib/Makefile
 run-make/no-duplicate-libs/Makefile
-run-make/no-input-file/Makefile
 run-make/no-intermediate-extras/Makefile
 run-make/obey-crate-type-flag/Makefile
 run-make/optimization-remarks-dir-pgo/Makefile

tests/run-make/no-input-file/rmake.rs

@@ -0,0 +1,9 @@
+extern crate run_make_support;
+
+use run_make_support::{diff, rustc};
+
+fn main() {
+    let output = rustc().arg("--print").arg("crate-name").run_fail();
+
+    diff().expected_file("no-input-file.stderr").actual_text(output.stderr).run();
+}