Rollup merge of #106557 - Ezrashaw:ui-test-fixups-1, r=GuillaumeGomez

Add some UI tests and reword error-code docs

Added UI tests for `E0013` and `E0015`. Error code docs for `E0015` were a bit unclear (they referred to all non-const errors in const context, when only non-const functions applied), so I touched them up a bit.

I also fixed up some issues in the new `error_codes.rs` tidy check (linked #106341), that I overlooked previously.

r? ``@GuillaumeGomez``

1 files changed, 15 insertions, 12 deletions

diff --git a/src/tools/tidy/src/error_codes.rs b/src/tools/tidy/src/error_codes.rs
index fdc9d789905..4b0a62fac83 100644
--- a/src/tools/tidy/src/error_codes.rs
+++ b/src/tools/tidy/src/error_codes.rs
@@ -15,8 +15,6 @@
 //!
 //! 4. We check that the error code is actually emitted by the compiler.
 //!   - This is done by searching `compiler/` with a regex.
-//!
-//! This tidy check was merged and refactored from two others. See #PR_NUM for information about linting changes that occurred during this refactor.
 
 use std::{ffi::OsStr, fs, path::Path};
 
@@ -57,7 +55,7 @@ pub fn check(root_path: &Path, search_paths: &[&Path], verbose: bool, bad: &mut
     let no_longer_emitted = check_error_codes_docs(root_path, &error_codes, &mut errors, verbose);
 
     // Stage 3: check list has UI tests
-    check_error_codes_tests(root_path, &error_codes, &mut errors, verbose);
+    check_error_codes_tests(root_path, &error_codes, &mut errors, verbose, &no_longer_emitted);
 
     // Stage 4: check list is emitted by compiler
     check_error_codes_used(search_paths, &error_codes, &mut errors, &no_longer_emitted, verbose);
@@ -174,8 +172,9 @@ fn check_error_codes_docs(
             return;
         }
 
-        let (found_code_example, found_proper_doctest, emit_ignore_warning, emit_no_longer_warning) =
+        let (found_code_example, found_proper_doctest, emit_ignore_warning, no_longer_emitted) =
             check_explanation_has_doctest(&contents, &err_code);
+
         if emit_ignore_warning {
             verbose_print!(
                 verbose,
@@ -183,13 +182,11 @@ fn check_error_codes_docs(
                 `IGNORE_DOCTEST_CHECK` constant instead."
             );
         }
-        if emit_no_longer_warning {
+
+        if no_longer_emitted {
             no_longer_emitted_codes.push(err_code.to_owned());
-            verbose_print!(
-                verbose,
-                "warning: Error code `{err_code}` is no longer emitted and should be removed entirely."
-            );
         }
+
         if !found_code_example {
             verbose_print!(
                 verbose,
@@ -226,7 +223,7 @@ fn check_explanation_has_doctest(explanation: &str, err_code: &str) -> (bool, bo
     let mut found_proper_doctest = false;
 
     let mut emit_ignore_warning = false;
-    let mut emit_no_longer_warning = false;
+    let mut no_longer_emitted = false;
 
     for line in explanation.lines() {
         let line = line.trim();
@@ -246,13 +243,13 @@ fn check_explanation_has_doctest(explanation: &str, err_code: &str) -> (bool, bo
         } else if line
             .starts_with("#### Note: this error code is no longer emitted by the compiler")
         {
-            emit_no_longer_warning = true;
+            no_longer_emitted = true;
             found_code_example = true;
             found_proper_doctest = true;
         }
     }
 
-    (found_code_example, found_proper_doctest, emit_ignore_warning, emit_no_longer_warning)
+    (found_code_example, found_proper_doctest, emit_ignore_warning, no_longer_emitted)
 }
 
 // Stage 3: Checks that each error code has a UI test in the correct directory
@@ -261,6 +258,7 @@ fn check_error_codes_tests(
     error_codes: &[String],
     errors: &mut Vec<String>,
     verbose: bool,
+    no_longer_emitted: &[String],
 ) {
     let tests_path = root_path.join(Path::new(ERROR_TESTS_PATH));
 
@@ -295,6 +293,11 @@ fn check_error_codes_tests(
             }
         };
 
+        if no_longer_emitted.contains(code) {
+            // UI tests *can't* contain error codes that are no longer emitted.
+            continue;
+        }
+
         let mut found_code = false;
 
         for line in file.lines() {