Add compare-output-lines-by-subset flag to compiletest

2 files changed, 68 insertions, 8 deletions

diff --git a/src/tools/compiletest/src/header.rs b/src/tools/compiletest/src/header.rs
index aaa70bf19b2..ccce62bd5b0 100644
--- a/src/tools/compiletest/src/header.rs
+++ b/src/tools/compiletest/src/header.rs
@@ -102,6 +102,9 @@ pub struct TestProps {
     pub dont_check_compiler_stdout: bool,
     // For UI tests, allows compiler to generate arbitrary output to stderr
     pub dont_check_compiler_stderr: bool,
+    // When checking the output of stdout or stderr check
+    // that the lines of expected output are a subset of the actual output.
+    pub compare_output_lines_by_subset: bool,
     // Don't force a --crate-type=dylib flag on the command line
     //
     // Set this for example if you have an auxiliary test file that contains
@@ -209,6 +212,7 @@ mod directives {
     pub const KNOWN_BUG: &'static str = "known-bug";
     pub const MIR_UNIT_TEST: &'static str = "unit-test";
     pub const REMAP_SRC_BASE: &'static str = "remap-src-base";
+    pub const COMPARE_OUTPUT_LINES_BY_SUBSET: &'static str = "compare-output-lines-by-subset";
     // This isn't a real directive, just one that is probably mistyped often
     pub const INCORRECT_COMPILER_FLAGS: &'static str = "compiler-flags";
 }
@@ -233,6 +237,7 @@ impl TestProps {
             check_run_results: false,
             dont_check_compiler_stdout: false,
             dont_check_compiler_stderr: false,
+            compare_output_lines_by_subset: false,
             no_prefer_dynamic: false,
             pretty_expanded: false,
             pretty_mode: "normal".to_string(),
@@ -467,6 +472,11 @@ impl TestProps {
                     s.trim().to_string()
                 });
                 config.set_name_directive(ln, REMAP_SRC_BASE, &mut self.remap_src_base);
+                config.set_name_directive(
+                    ln,
+                    COMPARE_OUTPUT_LINES_BY_SUBSET,
+                    &mut self.compare_output_lines_by_subset,
+                );
             });
         }
 
diff --git a/src/tools/compiletest/src/runtest.rs b/src/tools/compiletest/src/runtest.rs
index 0fa5c54ae8e..aed5641b673 100644
--- a/src/tools/compiletest/src/runtest.rs
+++ b/src/tools/compiletest/src/runtest.rs
@@ -3238,17 +3238,35 @@ impl<'test> TestCx<'test> {
         match output_kind {
             TestOutput::Compile => {
                 if !self.props.dont_check_compiler_stdout {
-                    errors +=
-                        self.compare_output(stdout_kind, &normalized_stdout, &expected_stdout);
+                    errors += self.compare_output(
+                        stdout_kind,
+                        &normalized_stdout,
+                        &expected_stdout,
+                        self.props.compare_output_lines_by_subset,
+                    );
                 }
                 if !self.props.dont_check_compiler_stderr {
-                    errors +=
-                        self.compare_output(stderr_kind, &normalized_stderr, &expected_stderr);
+                    errors += self.compare_output(
+                        stderr_kind,
+                        &normalized_stderr,
+                        &expected_stderr,
+                        self.props.compare_output_lines_by_subset,
+                    );
                 }
             }
             TestOutput::Run => {
-                errors += self.compare_output(stdout_kind, &normalized_stdout, &expected_stdout);
-                errors += self.compare_output(stderr_kind, &normalized_stderr, &expected_stderr);
+                errors += self.compare_output(
+                    stdout_kind,
+                    &normalized_stdout,
+                    &expected_stdout,
+                    self.props.compare_output_lines_by_subset,
+                );
+                errors += self.compare_output(
+                    stderr_kind,
+                    &normalized_stderr,
+                    &expected_stderr,
+                    self.props.compare_output_lines_by_subset,
+                );
             }
         }
         errors
@@ -3332,7 +3350,12 @@ impl<'test> TestCx<'test> {
                 )
             });
 
-            errors += self.compare_output("fixed", &fixed_code, &expected_fixed);
+            errors += self.compare_output(
+                "fixed",
+                &fixed_code,
+                &expected_fixed,
+                self.props.compare_output_lines_by_subset,
+            );
         } else if !expected_fixed.is_empty() {
             panic!(
                 "the `// run-rustfix` directive wasn't found but a `*.fixed` \
@@ -3790,11 +3813,38 @@ impl<'test> TestCx<'test> {
         }
     }
 
-    fn compare_output(&self, kind: &str, actual: &str, expected: &str) -> usize {
+    fn compare_output(
+        &self,
+        kind: &str,
+        actual: &str,
+        expected: &str,
+        compare_output_by_lines: bool,
+    ) -> usize {
         if actual == expected {
             return 0;
         }
 
+        let tmp;
+        let (expected, actual): (&str, &str) = if compare_output_by_lines {
+            let actual_lines: HashSet<_> = actual.lines().collect();
+            let expected_lines: Vec<_> = expected.lines().collect();
+            let mut used = expected_lines.clone();
+            used.retain(|line| actual_lines.contains(line));
+            // check if `expected` contains a subset of the lines of `actual`
+            if used.len() == expected_lines.len() && (expected.is_empty() == actual.is_empty()) {
+                return 0;
+            }
+            if expected_lines.is_empty() {
+                // if we have no lines to check, force a full overwite
+                ("", actual)
+            } else {
+                tmp = (expected_lines.join("\n"), used.join("\n"));
+                (&tmp.0, &tmp.1)
+            }
+        } else {
+            (expected, actual)
+        };
+
         if !self.config.bless {
             if expected.is_empty() {
                 println!("normalized {}:\n{}\n", kind, actual);