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

9 files changed, 146 insertions, 5 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 552b446a1e7..8a9701acae1 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -3343,6 +3343,7 @@ version = "0.0.0"
 dependencies = [
  "object 0.34.0",
  "regex",
+ "similar",
  "wasmparser",
 ]
 
@@ -5139,6 +5140,12 @@ 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"
 source = "registry+https://github.com/rust-lang/crates.io-index"
diff --git a/src/tools/run-make-support/Cargo.toml b/src/tools/run-make-support/Cargo.toml
index 3ea35c7940c..61a24c97e77 100644
--- a/src/tools/run-make-support/Cargo.toml
+++ b/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
diff --git a/src/tools/run-make-support/src/diff/mod.rs b/src/tools/run-make-support/src/diff/mod.rs
new file mode 100644
index 00000000000..54532c6e35b
--- /dev/null
+++ b/src/tools/run-make-support/src/diff/mod.rs
@@ -0,0 +1,81 @@
+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>,
+    expected_name: Option<String>,
+    actual: Option<String>,
+    actual_name: Option<String>,
+}
+
+impl Diff {
+    /// Construct a bare `diff` invocation.
+    pub fn new() -> Self {
+        Self { expected: None, expected_name: None, actual: None, actual_name: 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 path = path.as_ref();
+        let content = std::fs::read_to_string(path).expect("failed to read file");
+        let name = path.to_string_lossy().to_string();
+
+        self.expected = Some(content);
+        self.expected_name = Some(name);
+        self
+    }
+
+    /// Specify the expected output for the diff from a given text string.
+    pub fn expected_text<T: AsRef<[u8]>>(&mut self, name: &str, text: T) -> &mut Self {
+        self.expected = Some(String::from_utf8_lossy(text.as_ref()).to_string());
+        self.expected_name = Some(name.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 path = path.as_ref();
+        let content = std::fs::read_to_string(path).expect("failed to read file");
+        let name = path.to_string_lossy().to_string();
+
+        self.actual = Some(content);
+        self.actual_name = Some(name);
+        self
+    }
+
+    /// Specify the actual output for the diff from a given text string.
+    pub fn actual_text<T: AsRef<[u8]>>(&mut self, name: &str, text: T) -> &mut Self {
+        self.actual = Some(String::from_utf8_lossy(text.as_ref()).to_string());
+        self.actual_name = Some(name.to_string());
+        self
+    }
+
+    /// Executes the diff process, prints any differences to the standard error.
+    #[track_caller]
+    pub fn run(&self) {
+        let expected = self.expected.as_ref().expect("expected text not set");
+        let actual = self.actual.as_ref().expect("actual text not set");
+        let expected_name = self.expected_name.as_ref().unwrap();
+        let actual_name = self.actual_name.as_ref().unwrap();
+
+        let output = TextDiff::from_lines(expected, actual)
+            .unified_diff()
+            .header(expected_name, actual_name)
+            .to_string();
+
+        if !output.is_empty() {
+            panic!(
+                "test failed: `{}` is different from `{}`\n\n{}",
+                expected_name, actual_name, output
+            )
+        }
+    }
+}
diff --git a/src/tools/run-make-support/src/diff/tests.rs b/src/tools/run-make-support/src/diff/tests.rs
new file mode 100644
index 00000000000..e6d72544b7e
--- /dev/null
+++ b/src/tools/run-make-support/src/diff/tests.rs
@@ -0,0 +1,39 @@
+#[cfg(test)]
+mod tests {
+    use crate::*;
+
+    #[test]
+    fn test_diff() {
+        let expected = "foo\nbar\nbaz\n";
+        let actual = "foo\nbar\nbaz\n";
+        diff().expected_text("EXPECTED_TEXT", expected).actual_text("ACTUAL_TEXT", actual).run();
+    }
+
+    #[test]
+    fn test_should_panic() {
+        let expected = "foo\nbar\nbaz\n";
+        let actual = "foo\nbaz\nbar\n";
+
+        let output = std::panic::catch_unwind(|| {
+            diff()
+                .expected_text("EXPECTED_TEXT", expected)
+                .actual_text("ACTUAL_TEXT", actual)
+                .run();
+        })
+        .unwrap_err();
+
+        let expected_output = "\
+test failed: `EXPECTED_TEXT` is different from `ACTUAL_TEXT`
+
+--- EXPECTED_TEXT
++++ ACTUAL_TEXT
+@@ -1,3 +1,3 @@
+ foo
++baz
+ bar
+-baz
+";
+
+        assert_eq!(output.downcast_ref::<String>().unwrap(), expected_output);
+    }
+}
diff --git a/src/tools/run-make-support/src/lib.rs b/src/tools/run-make-support/src/lib.rs
index e723e824ed6..76e8838d27c 100644
--- a/src/tools/run-make-support/src/lib.rs
+++ b/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};
diff --git a/src/tools/run-make-support/src/rustc.rs b/src/tools/run-make-support/src/rustc.rs
index 9bf41c6e2e9..ddaae3236c2 100644
--- a/src/tools/run-make-support/src/rustc.rs
+++ b/src/tools/run-make-support/src/rustc.rs
@@ -148,6 +148,13 @@ impl Rustc {
         self
     }
 
+    /// Specify the print request.
+    pub fn print(&mut self, request: &str) -> &mut Self {
+        self.cmd.arg("--print");
+        self.cmd.arg(request);
+        self
+    }
+
     /// Add an extra argument to the linker invocation, via `-Clink-arg`.
     pub fn link_arg(&mut self, link_arg: &str) -> &mut Self {
         self.cmd.arg(format!("-Clink-arg={link_arg}"));
diff --git a/src/tools/tidy/src/allowed_run_make_makefiles.txt b/src/tools/tidy/src/allowed_run_make_makefiles.txt
index f0ed0ae806f..4598a658b31 100644
--- a/src/tools/tidy/src/allowed_run_make_makefiles.txt
+++ b/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
diff --git a/tests/run-make/no-input-file/Makefile b/tests/run-make/no-input-file/Makefile
deleted file mode 100644
index a754573a524..00000000000
--- a/tests/run-make/no-input-file/Makefile
+++ /dev/null
@@ -1,4 +0,0 @@
-include ../tools.mk
-
-all:
-	$(RUSTC) --print crate-name 2>&1 | diff - no-input-file.stderr
diff --git a/tests/run-make/no-input-file/rmake.rs b/tests/run-make/no-input-file/rmake.rs
new file mode 100644
index 00000000000..26df7e80dfb
--- /dev/null
+++ b/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().print("crate-name").run_fail_assert_exit_code(1);
+
+    diff().expected_file("no-input-file.stderr").actual_text("output", output.stderr).run();
+}