be more specific about what the pattern expects

Author: RalfJung

src/status_emitter.rs

@@ -419,10 +419,13 @@ fn print_error(error: &Error, path: &Path) {
         Error::PatternNotFound(pattern) => {
             let msg = match &**pattern {
                 Pattern::SubString(s) => {
-                    format!("substring `{s}` {} in stderr output", "not found")
+                    format!("`{s}` not found in diagnostics for line {}", pattern.line())
                 }
                 Pattern::Regex(r) => {
-                    format!("`/{r}/` does {} stderr output", "not match")
+                    format!(
+                        "`/{r}/` does not match diagnostics for line {}",
+                        pattern.line()
+                    )
                 }
             };
             create_error(

tests/integrations/basic-fail/Cargo.stdout

@@ -17,7 +17,7 @@ tests/actual_tests/rustc_ice.rs ... FAILED
 tests/actual_tests/bad_pattern.rs FAILED:
 command: "rustc" "--error-format=json" "--extern" "basic_fail=$DIR/$DIR/../../../target/$TMP/$TRIPLE/debug/libbasic_fail.rlib" "--extern" "basic_fail=$DIR/$DIR/../../../target/$TMP/$TRIPLE/debug/libbasic_fail-$HASH.rmeta" "-L" "$DIR/$DIR/../../../target/$TMP/$TRIPLE/debug" "-L" "$DIR/$DIR/../../../target/$TMP/$TRIPLE/debug" "--out-dir" "$TMP "tests/actual_tests/bad_pattern.rs" "--edition" "2021"
 
-error: substring `miesmätsched types` not found in stderr output
+error: `miesmätsched types` not found in diagnostics for line 5
  --> tests/actual_tests/bad_pattern.rs:5:17
   |
 5 |     //~^ ERROR: miesmätsched types
@@ -234,7 +234,7 @@ command: "rustc" "--error-format=json" "--extern" "basic_fail=$DIR/$DIR/../../..
 
 fail test got exit status: 101, but expected 1
 
-error: substring `mismatched types` not found in stderr output
+error: `mismatched types` not found in diagnostics for line 11
   --> tests/actual_tests/rustc_ice.rs:11:17
    |
 11 |     //~^ ERROR: mismatched types
@@ -539,7 +539,7 @@ full stdout:
 tests/actual_tests_bless/pass_with_annotation.rs FAILED:
 command: "rustc" "--error-format=json" "--extern" "basic_fail=$DIR/$DIR/../../../target/$TMP/$TRIPLE/debug/libbasic_fail.rlib" "--extern" "basic_fail=$DIR/$DIR/../../../target/$TMP/$TRIPLE/debug/libbasic_fail-$HASH.rmeta" "-L" "$DIR/$DIR/../../../target/$TMP/$TRIPLE/debug" "-L" "$DIR/$DIR/../../../target/$TMP/$TRIPLE/debug" "--out-dir" "$TMP "tests/actual_tests_bless/pass_with_annotation.rs" "--edition" "2021"
 
-error: substring `the cake is a lie` not found in stderr output
+error: `the cake is a lie` not found in diagnostics for line 3
  --> tests/actual_tests_bless/pass_with_annotation.rs:3:12
   |
 3 | //~ ERROR: the cake is a lie
@@ -605,7 +605,7 @@ full stdout:
 tests/actual_tests_bless/revisions_bad.rs (revision `bar`) FAILED:
 command: "rustc" "--error-format=json" "--extern" "basic_fail=$DIR/$DIR/../../../target/$TMP/$TRIPLE/debug/libbasic_fail.rlib" "--extern" "basic_fail=$DIR/$DIR/../../../target/$TMP/$TRIPLE/debug/libbasic_fail-$HASH.rmeta" "-L" "$DIR/$DIR/../../../target/$TMP/$TRIPLE/debug" "-L" "$DIR/$DIR/../../../target/$TMP/$TRIPLE/debug" "--out-dir" "$TMP "tests/actual_tests_bless/revisions_bad.rs" "--cfg=bar" "--edition" "2021"
 
-error: substring ``main` function not found in crate `revisions_bad`` not found in stderr output
+error: ``main` function not found in crate `revisions_bad`` not found in diagnostics for line 4
  --> tests/actual_tests_bless/revisions_bad.rs:4:31
   |
 4 | //@[bar] error-in-other-file: `main` function not found in crate `revisions_bad`
@@ -787,7 +787,7 @@ tests/actual_tests_bless_yolo/rustfix-maybe-incorrect.rs ... ok
 tests/actual_tests_bless_yolo/revisions_bad.rs (revision `bar`) FAILED:
 command: "rustc" "--error-format=json" "--extern" "basic_fail=$DIR/$DIR/../../../target/$TMP/$TRIPLE/debug/libbasic_fail.rlib" "--extern" "basic_fail=$DIR/$DIR/../../../target/$TMP/$TRIPLE/debug/libbasic_fail-$HASH.rmeta" "-L" "$DIR/$DIR/../../../target/$TMP/$TRIPLE/debug" "-L" "$DIR/$DIR/../../../target/$TMP/$TRIPLE/debug" "--out-dir" "$TMP "tests/actual_tests_bless_yolo/revisions_bad.rs" "--cfg=bar" "--edition" "2021"
 
-error: substring ``main` function not found in crate `revisions_bad`` not found in stderr output
+error: ``main` function not found in crate `revisions_bad`` not found in diagnostics for line 4
  --> tests/actual_tests_bless_yolo/revisions_bad.rs:4:31
   |
 4 | //@[bar] error-in-other-file: `main` function not found in crate `revisions_bad`