Rollup merge of #148510 - Zalathar:known-directives, r=jieyouxu

compiletest: Do the known-directives check only once, and improve its error message

This PR is a combination of three changes:
- Store the list of known directives in a set, so that checking a directive name doesn't require a linear scan
- Extract the known-directives check out of `iter_directives` and do it only once, instead of multiple times per file
- Improve the error message for unknown directives, [as requested on Zulip](https://rust-lang.zulipchat.com/#narrow/channel/326414-t-infra.2Fbootstrap/topic/Compiletest.20directive.20parsing.20error/with/553598083)

The change to error messages is fused with the extraction, since doing it independently would have been more awkward.

---

## Before

```text
Testing stage1 with compiletest suite=coverage mode=coverage-map (aarch64-apple-darwin)
errors encountered during EarlyProps parsing: /Users/stuart/Dev/rust/rust/tests/coverage/trivial.rs
2025-11-05T01:55:46.440012Z ERROR compiletest::directives: /Users/stuart/Dev/rust/rust/tests/coverage/trivial.rs:2: detected unknown compiletest test directive `add-core-stubs`

thread '<unnamed>' (36268582) panicked at src/tools/compiletest/src/directives.rs:72:13:
errors encountered during EarlyProps parsing
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
```

## After

```text
Testing stage1 with compiletest suite=coverage mode=coverage-map (aarch64-apple-darwin)

thread '<unnamed>' (36270772) panicked at src/tools/compiletest/src/lib.rs:876:9:
directives check failed:
ERROR: unknown compiletest directive `add-core-stubs` at /Users/stuart/Dev/rust/rust/tests/coverage/trivial.rs:2
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
```

Author: matthiaskrgr

src/tools/compiletest/src/directives.rs

@@ -11,7 +11,7 @@ use crate::debuggers::{extract_cdb_version, extract_gdb_version};
 pub(crate) use crate::directives::auxiliary::AuxProps;
 use crate::directives::auxiliary::parse_and_update_aux;
 use crate::directives::directive_names::{
-    KNOWN_DIRECTIVE_NAMES, KNOWN_HTMLDOCCK_DIRECTIVE_NAMES, KNOWN_JSONDOCCK_DIRECTIVE_NAMES,
+    KNOWN_DIRECTIVE_NAMES_SET, KNOWN_HTMLDOCCK_DIRECTIVE_NAMES, KNOWN_JSONDOCCK_DIRECTIVE_NAMES,
 };
 pub(crate) use crate::directives::file::FileDirectives;
 use crate::directives::line::{DirectiveLine, line_directive};
@@ -53,25 +53,17 @@ impl EarlyProps {
         config: &Config,
         file_directives: &FileDirectives<'_>,
     ) -> Self {
-        let testfile = file_directives.path;
         let mut props = EarlyProps::default();
-        let mut poisoned = false;
 
         iter_directives(
             config.mode,
-            &mut poisoned,
             file_directives,
             // (dummy comment to force args into vertical layout)
             &mut |ln: &DirectiveLine<'_>| {
                 config.parse_and_update_revisions(ln, &mut props.revisions);
             },
         );
 
-        if poisoned {
-            eprintln!("errors encountered during EarlyProps parsing: {}", testfile);
-            panic!("errors encountered during EarlyProps parsing");
-        }
-
         props
     }
 }
@@ -358,12 +350,10 @@ impl TestProps {
             let file_contents = fs::read_to_string(testfile).unwrap();
             let file_directives = FileDirectives::from_file_contents(testfile, &file_contents);
 
-            let mut poisoned = false;
-
             iter_directives(
                 config.mode,
-                &mut poisoned,
                 &file_directives,
+                // (dummy comment to force args into vertical layout)
                 &mut |ln: &DirectiveLine<'_>| {
                     if !ln.applies_to_test_revision(test_revision) {
                         return;
@@ -634,11 +624,6 @@ impl TestProps {
                     );
                 },
             );
-
-            if poisoned {
-                eprintln!("errors encountered during TestProps parsing: {}", testfile);
-                panic!("errors encountered during TestProps parsing");
-            }
         }
 
         if self.should_ice {
@@ -775,6 +760,34 @@ impl TestProps {
     }
 }
 
+pub(crate) fn do_early_directives_check(
+    mode: TestMode,
+    file_directives: &FileDirectives<'_>,
+) -> Result<(), String> {
+    let testfile = file_directives.path;
+
+    for directive_line @ DirectiveLine { line_number, .. } in &file_directives.lines {
+        let CheckDirectiveResult { is_known_directive, trailing_directive } =
+            check_directive(directive_line, mode);
+
+        if !is_known_directive {
+            return Err(format!(
+                "ERROR: unknown compiletest directive `{directive}` at {testfile}:{line_number}",
+                directive = directive_line.display(),
+            ));
+        }
+
+        if let Some(trailing_directive) = &trailing_directive {
+            return Err(format!(
+                "ERROR: detected trailing compiletest directive `{trailing_directive}` at {testfile}:{line_number}\n\
+                HELP: put the directive on its own line: `//@ {trailing_directive}`"
+            ));
+        }
+    }
+
+    Ok(())
+}
+
 pub(crate) struct CheckDirectiveResult<'ln> {
     is_known_directive: bool,
     trailing_directive: Option<&'ln str>,
@@ -786,7 +799,7 @@ fn check_directive<'a>(
 ) -> CheckDirectiveResult<'a> {
     let &DirectiveLine { name: directive_name, .. } = directive_ln;
 
-    let is_known_directive = KNOWN_DIRECTIVE_NAMES.contains(&directive_name)
+    let is_known_directive = KNOWN_DIRECTIVE_NAMES_SET.contains(&directive_name)
         || match mode {
             TestMode::Rustdoc => KNOWN_HTMLDOCCK_DIRECTIVE_NAMES.contains(&directive_name),
             TestMode::RustdocJson => KNOWN_JSONDOCCK_DIRECTIVE_NAMES.contains(&directive_name),
@@ -799,7 +812,7 @@ fn check_directive<'a>(
     let trailing_directive = directive_ln
         .remark_after_space()
         .map(|remark| remark.trim_start().split(' ').next().unwrap())
-        .filter(|token| KNOWN_DIRECTIVE_NAMES.contains(token));
+        .filter(|token| KNOWN_DIRECTIVE_NAMES_SET.contains(token));
 
     // FIXME(Zalathar): Consider emitting specialized error/help messages for
     // bogus directive names that are similar to real ones, e.g.:
@@ -811,7 +824,6 @@ fn check_directive<'a>(
 
 fn iter_directives(
     mode: TestMode,
-    poisoned: &mut bool,
     file_directives: &FileDirectives<'_>,
     it: &mut dyn FnMut(&DirectiveLine<'_>),
 ) {
@@ -837,36 +849,7 @@ fn iter_directives(
         }
     }
 
-    for directive_line @ &DirectiveLine { line_number, .. } in &file_directives.lines {
-        // Perform unknown directive check on Rust files.
-        if testfile.extension() == Some("rs") {
-            let CheckDirectiveResult { is_known_directive, trailing_directive } =
-                check_directive(directive_line, mode);
-
-            if !is_known_directive {
-                *poisoned = true;
-
-                error!(
-                    "{testfile}:{line_number}: detected unknown compiletest test directive `{}`",
-                    directive_line.display(),
-                );
-
-                return;
-            }
-
-            if let Some(trailing_directive) = &trailing_directive {
-                *poisoned = true;
-
-                error!(
-                    "{testfile}:{line_number}: detected trailing compiletest test directive `{}`",
-                    trailing_directive,
-                );
-                help!("put the trailing directive in its own line: `//@ {}`", trailing_directive);
-
-                return;
-            }
-        }
-
+    for directive_line in &file_directives.lines {
         it(directive_line);
     }
 }
@@ -1304,12 +1287,9 @@ pub(crate) fn make_test_description(
     let mut ignore_message = None;
     let mut should_fail = false;
 
-    let mut local_poisoned = false;
-
     // Scan through the test file to handle `ignore-*`, `only-*`, and `needs-*` directives.
     iter_directives(
         config.mode,
-        &mut local_poisoned,
         file_directives,
         &mut |ln @ &DirectiveLine { line_number, .. }| {
             if !ln.applies_to_test_revision(test_revision) {
@@ -1358,11 +1338,6 @@ pub(crate) fn make_test_description(
         },
     );
 
-    if local_poisoned {
-        eprintln!("errors encountered when trying to make test description: {}", path);
-        panic!("errors encountered when trying to make test description");
-    }
-
     // The `should-fail` annotation doesn't apply to pretty tests,
     // since we run the pretty printer across all tests by default.
     // If desired, we could add a `should-fail-pretty` annotation.

src/tools/compiletest/src/directives/directive_names.rs

@@ -1,3 +1,9 @@
+use std::collections::HashSet;
+use std::sync::LazyLock;
+
+pub(crate) static KNOWN_DIRECTIVE_NAMES_SET: LazyLock<HashSet<&str>> =
+    LazyLock::new(|| KNOWN_DIRECTIVE_NAMES.iter().copied().collect());
+
 /// This was originally generated by collecting directives from ui tests and then extracting their
 /// directive names. This is **not** an exhaustive list of all possible directives. Instead, this is
 /// a best-effort approximation for diagnostics. Add new directives to this list when needed.

src/tools/compiletest/src/directives/tests.rs

@@ -3,8 +3,8 @@ use semver::Version;
 
 use crate::common::{Config, Debugger, TestMode};
 use crate::directives::{
-    AuxProps, DirectivesCache, EarlyProps, Edition, EditionRange, FileDirectives,
-    extract_llvm_version, extract_version_range, iter_directives, line_directive, parse_edition,
+    self, AuxProps, DirectivesCache, EarlyProps, Edition, EditionRange, FileDirectives,
+    extract_llvm_version, extract_version_range, line_directive, parse_edition,
     parse_normalize_rule,
 };
 use crate::executor::{CollectedTestDesc, ShouldFail};
@@ -767,7 +767,10 @@ fn threads_support() {
 
 fn run_path(poisoned: &mut bool, path: &Utf8Path, file_contents: &str) {
     let file_directives = FileDirectives::from_file_contents(path, file_contents);
-    iter_directives(TestMode::Ui, poisoned, &file_directives, &mut |_| {});
+    let result = directives::do_early_directives_check(TestMode::Ui, &file_directives);
+    if result.is_err() {
+        *poisoned = true;
+    }
 }
 
 #[test]

src/tools/compiletest/src/lib.rs

@@ -869,6 +869,12 @@ fn make_test(cx: &TestCollectorCx, collector: &mut TestCollector, testpaths: &Te
     let file_contents =
         fs::read_to_string(&test_path).expect("reading test file for directives should succeed");
     let file_directives = FileDirectives::from_file_contents(&test_path, &file_contents);
+
+    if let Err(message) = directives::do_early_directives_check(cx.config.mode, &file_directives) {
+        // FIXME(Zalathar): Overhaul compiletest error handling so that we
+        // don't have to resort to ad-hoc panics everywhere.
+        panic!("directives check failed:\n{message}");
+    }
     let early_props = EarlyProps::from_file_directives(&cx.config, &file_directives);
 
     // Normally we create one structure per revision, with two exceptions: