Verify llvm-needs-components are not empty and match the --target value

6 files changed, 248 insertions, 66 deletions

diff --git a/src/doc/rustc-dev-guide/src/tests/directives.md b/src/doc/rustc-dev-guide/src/tests/directives.md
index 5c3ae359ba0..89e4d3e9b58 100644
--- a/src/doc/rustc-dev-guide/src/tests/directives.md
+++ b/src/doc/rustc-dev-guide/src/tests/directives.md
@@ -293,8 +293,6 @@ See [Pretty-printer](compiletest.md#pretty-printer-tests).
 
 - `no-auto-check-cfg` — disable auto check-cfg (only for `--check-cfg` tests)
 - [`revisions`](compiletest.md#revisions) — compile multiple times
-- [`unused-revision-names`](compiletest.md#ignoring-unused-revision-names) -
-      suppress tidy checks for mentioning unknown revision names
 -[`forbid-output`](compiletest.md#incremental-tests) — incremental cfail rejects
       output pattern
 - [`should-ice`](compiletest.md#incremental-tests) — incremental cfail should
@@ -315,6 +313,17 @@ test suites that use those tools:
 - `llvm-cov-flags` adds extra flags when running LLVM's `llvm-cov` tool.
   - Used by [coverage tests](compiletest.md#coverage-tests) in `coverage-run` mode.
 
+### Tidy specific directives
+
+The following directives control how the [tidy script](../conventions.md#formatting)
+verifies tests.
+
+- `ignore-tidy-target-specific-tests` disables checking that the appropriate
+  LLVM component is required (via a `needs-llvm-components` directive) when a
+  test is compiled for a specific target (via the `--target` flag in a
+  `compile-flag` directive).
+- [`unused-revision-names`](compiletest.md#ignoring-unused-revision-names) -
+      suppress tidy checks for mentioning unknown revision names.
 
 ## Substitutions
 
diff --git a/src/tools/compiletest/src/directives.rs b/src/tools/compiletest/src/directives.rs
index a1f76a07556..69ff846330e 100644
--- a/src/tools/compiletest/src/directives.rs
+++ b/src/tools/compiletest/src/directives.rs
@@ -59,9 +59,9 @@ impl EarlyProps {
             &mut poisoned,
             testfile,
             rdr,
-            &mut |DirectiveLine { raw_directive: ln, .. }| {
-                parse_and_update_aux(config, ln, &mut props.aux);
-                config.parse_and_update_revisions(testfile, ln, &mut props.revisions);
+            &mut |DirectiveLine { line_number, raw_directive: ln, .. }| {
+                parse_and_update_aux(config, ln, testfile, line_number, &mut props.aux);
+                config.parse_and_update_revisions(testfile, line_number, ln, &mut props.revisions);
             },
         );
 
@@ -351,7 +351,7 @@ impl TestProps {
                 &mut poisoned,
                 testfile,
                 file,
-                &mut |directive @ DirectiveLine { raw_directive: ln, .. }| {
+                &mut |directive @ DirectiveLine { line_number, raw_directive: ln, .. }| {
                     if !directive.applies_to_test_revision(test_revision) {
                         return;
                     }
@@ -361,17 +361,28 @@ impl TestProps {
                     config.push_name_value_directive(
                         ln,
                         ERROR_PATTERN,
+                        testfile,
+                        line_number,
                         &mut self.error_patterns,
                         |r| r,
                     );
                     config.push_name_value_directive(
                         ln,
                         REGEX_ERROR_PATTERN,
+                        testfile,
+                        line_number,
                         &mut self.regex_error_patterns,
                         |r| r,
                     );
 
-                    config.push_name_value_directive(ln, DOC_FLAGS, &mut self.doc_flags, |r| r);
+                    config.push_name_value_directive(
+                        ln,
+                        DOC_FLAGS,
+                        testfile,
+                        line_number,
+                        &mut self.doc_flags,
+                        |r| r,
+                    );
 
                     fn split_flags(flags: &str) -> Vec<String> {
                         // Individual flags can be single-quoted to preserve spaces; see
@@ -386,7 +397,9 @@ impl TestProps {
                             .collect::<Vec<_>>()
                     }
 
-                    if let Some(flags) = config.parse_name_value_directive(ln, COMPILE_FLAGS) {
+                    if let Some(flags) =
+                        config.parse_name_value_directive(ln, COMPILE_FLAGS, testfile, line_number)
+                    {
                         let flags = split_flags(&flags);
                         for flag in &flags {
                             if flag == "--edition" || flag.starts_with("--edition=") {
@@ -395,25 +408,40 @@ impl TestProps {
                         }
                         self.compile_flags.extend(flags);
                     }
-                    if config.parse_name_value_directive(ln, INCORRECT_COMPILER_FLAGS).is_some() {
+                    if config
+                        .parse_name_value_directive(
+                            ln,
+                            INCORRECT_COMPILER_FLAGS,
+                            testfile,
+                            line_number,
+                        )
+                        .is_some()
+                    {
                         panic!("`compiler-flags` directive should be spelled `compile-flags`");
                     }
 
-                    if let Some(edition) = config.parse_edition(ln) {
+                    if let Some(edition) = config.parse_edition(ln, testfile, line_number) {
                         // The edition is added at the start, since flags from //@compile-flags must
                         // be passed to rustc last.
                         self.compile_flags.insert(0, format!("--edition={}", edition.trim()));
                         has_edition = true;
                     }
 
-                    config.parse_and_update_revisions(testfile, ln, &mut self.revisions);
+                    config.parse_and_update_revisions(
+                        testfile,
+                        line_number,
+                        ln,
+                        &mut self.revisions,
+                    );
 
-                    if let Some(flags) = config.parse_name_value_directive(ln, RUN_FLAGS) {
+                    if let Some(flags) =
+                        config.parse_name_value_directive(ln, RUN_FLAGS, testfile, line_number)
+                    {
                         self.run_flags.extend(split_flags(&flags));
                     }
 
                     if self.pp_exact.is_none() {
-                        self.pp_exact = config.parse_pp_exact(ln, testfile);
+                        self.pp_exact = config.parse_pp_exact(ln, testfile, line_number);
                     }
 
                     config.set_name_directive(ln, SHOULD_ICE, &mut self.should_ice);
@@ -435,7 +463,9 @@ impl TestProps {
                     );
                     config.set_name_directive(ln, NO_PREFER_DYNAMIC, &mut self.no_prefer_dynamic);
 
-                    if let Some(m) = config.parse_name_value_directive(ln, PRETTY_MODE) {
+                    if let Some(m) =
+                        config.parse_name_value_directive(ln, PRETTY_MODE, testfile, line_number)
+                    {
                         self.pretty_mode = m;
                     }
 
@@ -446,35 +476,45 @@ impl TestProps {
                     );
 
                     // Call a helper method to deal with aux-related directives.
-                    parse_and_update_aux(config, ln, &mut self.aux);
+                    parse_and_update_aux(config, ln, testfile, line_number, &mut self.aux);
 
                     config.push_name_value_directive(
                         ln,
                         EXEC_ENV,
+                        testfile,
+                        line_number,
                         &mut self.exec_env,
                         Config::parse_env,
                     );
                     config.push_name_value_directive(
                         ln,
                         UNSET_EXEC_ENV,
+                        testfile,
+                        line_number,
                         &mut self.unset_exec_env,
                         |r| r.trim().to_owned(),
                     );
                     config.push_name_value_directive(
                         ln,
                         RUSTC_ENV,
+                        testfile,
+                        line_number,
                         &mut self.rustc_env,
                         Config::parse_env,
                     );
                     config.push_name_value_directive(
                         ln,
                         UNSET_RUSTC_ENV,
+                        testfile,
+                        line_number,
                         &mut self.unset_rustc_env,
                         |r| r.trim().to_owned(),
                     );
                     config.push_name_value_directive(
                         ln,
                         FORBID_OUTPUT,
+                        testfile,
+                        line_number,
                         &mut self.forbid_output,
                         |r| r,
                     );
@@ -510,7 +550,7 @@ impl TestProps {
                     }
 
                     if let Some(code) = config
-                        .parse_name_value_directive(ln, FAILURE_STATUS)
+                        .parse_name_value_directive(ln, FAILURE_STATUS, testfile, line_number)
                         .and_then(|code| code.trim().parse::<i32>().ok())
                     {
                         self.failure_status = Some(code);
@@ -531,6 +571,8 @@ impl TestProps {
                     config.set_name_value_directive(
                         ln,
                         ASSEMBLY_OUTPUT,
+                        testfile,
+                        line_number,
                         &mut self.assembly_output,
                         |r| r.trim().to_string(),
                     );
@@ -543,7 +585,9 @@ impl TestProps {
 
                     // Unlike the other `name_value_directive`s this needs to be handled manually,
                     // because it sets a `bool` flag.
-                    if let Some(known_bug) = config.parse_name_value_directive(ln, KNOWN_BUG) {
+                    if let Some(known_bug) =
+                        config.parse_name_value_directive(ln, KNOWN_BUG, testfile, line_number)
+                    {
                         let known_bug = known_bug.trim();
                         if known_bug == "unknown"
                             || known_bug.split(',').all(|issue_ref| {
@@ -571,16 +615,25 @@ impl TestProps {
                     config.set_name_value_directive(
                         ln,
                         TEST_MIR_PASS,
+                        testfile,
+                        line_number,
                         &mut self.mir_unit_test,
                         |s| s.trim().to_string(),
                     );
                     config.set_name_directive(ln, REMAP_SRC_BASE, &mut self.remap_src_base);
 
-                    if let Some(flags) = config.parse_name_value_directive(ln, LLVM_COV_FLAGS) {
+                    if let Some(flags) =
+                        config.parse_name_value_directive(ln, LLVM_COV_FLAGS, testfile, line_number)
+                    {
                         self.llvm_cov_flags.extend(split_flags(&flags));
                     }
 
-                    if let Some(flags) = config.parse_name_value_directive(ln, FILECHECK_FLAGS) {
+                    if let Some(flags) = config.parse_name_value_directive(
+                        ln,
+                        FILECHECK_FLAGS,
+                        testfile,
+                        line_number,
+                    ) {
                         self.filecheck_flags.extend(split_flags(&flags));
                     }
 
@@ -588,9 +641,12 @@ impl TestProps {
 
                     self.update_add_core_stubs(ln, config);
 
-                    if let Some(err_kind) =
-                        config.parse_name_value_directive(ln, DONT_REQUIRE_ANNOTATIONS)
-                    {
+                    if let Some(err_kind) = config.parse_name_value_directive(
+                        ln,
+                        DONT_REQUIRE_ANNOTATIONS,
+                        testfile,
+                        line_number,
+                    ) {
                         self.dont_require_annotations
                             .insert(ErrorKind::expect_from_user_str(err_kind.trim()));
                     }
@@ -1206,6 +1262,7 @@ impl Config {
     fn parse_and_update_revisions(
         &self,
         testfile: &Utf8Path,
+        line_number: usize,
         line: &str,
         existing: &mut Vec<String>,
     ) {
@@ -1219,7 +1276,8 @@ impl Config {
         const FILECHECK_FORBIDDEN_REVISION_NAMES: [&str; 9] =
             ["CHECK", "COM", "NEXT", "SAME", "EMPTY", "NOT", "COUNT", "DAG", "LABEL"];
 
-        if let Some(raw) = self.parse_name_value_directive(line, "revisions") {
+        if let Some(raw) = self.parse_name_value_directive(line, "revisions", testfile, line_number)
+        {
             if self.mode == TestMode::RunMake {
                 panic!("`run-make` tests do not support revisions: {}", testfile);
             }
@@ -1264,8 +1322,13 @@ impl Config {
         (name.to_owned(), value.to_owned())
     }
 
-    fn parse_pp_exact(&self, line: &str, testfile: &Utf8Path) -> Option<Utf8PathBuf> {
-        if let Some(s) = self.parse_name_value_directive(line, "pp-exact") {
+    fn parse_pp_exact(
+        &self,
+        line: &str,
+        testfile: &Utf8Path,
+        line_number: usize,
+    ) -> Option<Utf8PathBuf> {
+        if let Some(s) = self.parse_name_value_directive(line, "pp-exact", testfile, line_number) {
             Some(Utf8PathBuf::from(&s))
         } else if self.parse_name_directive(line, "pp-exact") {
             testfile.file_name().map(Utf8PathBuf::from)
@@ -1306,19 +1369,31 @@ impl Config {
         line.starts_with("no-") && self.parse_name_directive(&line[3..], directive)
     }
 
-    pub fn parse_name_value_directive(&self, line: &str, directive: &str) -> Option<String> {
+    pub fn parse_name_value_directive(
+        &self,
+        line: &str,
+        directive: &str,
+        testfile: &Utf8Path,
+        line_number: usize,
+    ) -> Option<String> {
         let colon = directive.len();
         if line.starts_with(directive) && line.as_bytes().get(colon) == Some(&b':') {
             let value = line[(colon + 1)..].to_owned();
             debug!("{}: {}", directive, value);
-            Some(expand_variables(value, self))
+            let value = expand_variables(value, self);
+            if value.is_empty() {
+                error!("{testfile}:{line_number}: empty value for directive `{directive}`");
+                help!("expected syntax is: `{directive}: value`");
+                panic!("empty directive value detected");
+            }
+            Some(value)
         } else {
             None
         }
     }
 
-    fn parse_edition(&self, line: &str) -> Option<String> {
-        self.parse_name_value_directive(line, "edition")
+    fn parse_edition(&self, line: &str, testfile: &Utf8Path, line_number: usize) -> Option<String> {
+        self.parse_name_value_directive(line, "edition", testfile, line_number)
     }
 
     fn set_name_directive(&self, line: &str, directive: &str, value: &mut bool) {
@@ -1340,11 +1415,14 @@ impl Config {
         &self,
         line: &str,
         directive: &str,
+        testfile: &Utf8Path,
+        line_number: usize,
         value: &mut Option<T>,
         parse: impl FnOnce(String) -> T,
     ) {
         if value.is_none() {
-            *value = self.parse_name_value_directive(line, directive).map(parse);
+            *value =
+                self.parse_name_value_directive(line, directive, testfile, line_number).map(parse);
         }
     }
 
@@ -1352,10 +1430,14 @@ impl Config {
         &self,
         line: &str,
         directive: &str,
+        testfile: &Utf8Path,
+        line_number: usize,
         values: &mut Vec<T>,
         parse: impl FnOnce(String) -> T,
     ) {
-        if let Some(value) = self.parse_name_value_directive(line, directive).map(parse) {
+        if let Some(value) =
+            self.parse_name_value_directive(line, directive, testfile, line_number).map(parse)
+        {
             values.push(value);
         }
     }
@@ -1672,9 +1754,9 @@ pub(crate) fn make_test_description<R: Read>(
             decision!(cfg::handle_ignore(config, ln));
             decision!(cfg::handle_only(config, ln));
             decision!(needs::handle_needs(&cache.needs, config, ln));
-            decision!(ignore_llvm(config, path, ln));
-            decision!(ignore_backends(config, path, ln));
-            decision!(needs_backends(config, path, ln));
+            decision!(ignore_llvm(config, path, ln, line_number));
+            decision!(ignore_backends(config, path, ln, line_number));
+            decision!(needs_backends(config, path, ln, line_number));
             decision!(ignore_cdb(config, ln));
             decision!(ignore_gdb(config, ln));
             decision!(ignore_lldb(config, ln));
@@ -1801,8 +1883,15 @@ fn ignore_lldb(config: &Config, line: &str) -> IgnoreDecision {
     IgnoreDecision::Continue
 }
 
-fn ignore_backends(config: &Config, path: &Utf8Path, line: &str) -> IgnoreDecision {
-    if let Some(backends_to_ignore) = config.parse_name_value_directive(line, "ignore-backends") {
+fn ignore_backends(
+    config: &Config,
+    path: &Utf8Path,
+    line: &str,
+    line_number: usize,
+) -> IgnoreDecision {
+    if let Some(backends_to_ignore) =
+        config.parse_name_value_directive(line, "ignore-backends", path, line_number)
+    {
         for backend in backends_to_ignore.split_whitespace().map(|backend| {
             match CodegenBackend::try_from(backend) {
                 Ok(backend) => backend,
@@ -1821,8 +1910,15 @@ fn ignore_backends(config: &Config, path: &Utf8Path, line: &str) -> IgnoreDecisi
     IgnoreDecision::Continue
 }
 
-fn needs_backends(config: &Config, path: &Utf8Path, line: &str) -> IgnoreDecision {
-    if let Some(needed_backends) = config.parse_name_value_directive(line, "needs-backends") {
+fn needs_backends(
+    config: &Config,
+    path: &Utf8Path,
+    line: &str,
+    line_number: usize,
+) -> IgnoreDecision {
+    if let Some(needed_backends) =
+        config.parse_name_value_directive(line, "needs-backends", path, line_number)
+    {
         if !needed_backends
             .split_whitespace()
             .map(|backend| match CodegenBackend::try_from(backend) {
@@ -1844,9 +1940,9 @@ fn needs_backends(config: &Config, path: &Utf8Path, line: &str) -> IgnoreDecisio
     IgnoreDecision::Continue
 }
 
-fn ignore_llvm(config: &Config, path: &Utf8Path, line: &str) -> IgnoreDecision {
+fn ignore_llvm(config: &Config, path: &Utf8Path, line: &str, line_number: usize) -> IgnoreDecision {
     if let Some(needed_components) =
-        config.parse_name_value_directive(line, "needs-llvm-components")
+        config.parse_name_value_directive(line, "needs-llvm-components", path, line_number)
     {
         let components: HashSet<_> = config.llvm_components.split_whitespace().collect();
         if let Some(missing_component) = needed_components
@@ -1867,7 +1963,9 @@ fn ignore_llvm(config: &Config, path: &Utf8Path, line: &str) -> IgnoreDecision {
     if let Some(actual_version) = &config.llvm_version {
         // Note that these `min` versions will check for not just major versions.
 
-        if let Some(version_string) = config.parse_name_value_directive(line, "min-llvm-version") {
+        if let Some(version_string) =
+            config.parse_name_value_directive(line, "min-llvm-version", path, line_number)
+        {
             let min_version = extract_llvm_version(&version_string);
             // Ignore if actual version is smaller than the minimum required version.
             if *actual_version < min_version {
@@ -1878,7 +1976,7 @@ fn ignore_llvm(config: &Config, path: &Utf8Path, line: &str) -> IgnoreDecision {
                 };
             }
         } else if let Some(version_string) =
-            config.parse_name_value_directive(line, "max-llvm-major-version")
+            config.parse_name_value_directive(line, "max-llvm-major-version", path, line_number)
         {
             let max_version = extract_llvm_version(&version_string);
             // Ignore if actual major version is larger than the maximum required major version.
@@ -1892,7 +1990,7 @@ fn ignore_llvm(config: &Config, path: &Utf8Path, line: &str) -> IgnoreDecision {
                 };
             }
         } else if let Some(version_string) =
-            config.parse_name_value_directive(line, "min-system-llvm-version")
+            config.parse_name_value_directive(line, "min-system-llvm-version", path, line_number)
         {
             let min_version = extract_llvm_version(&version_string);
             // Ignore if using system LLVM and actual version
@@ -1905,7 +2003,7 @@ fn ignore_llvm(config: &Config, path: &Utf8Path, line: &str) -> IgnoreDecision {
                 };
             }
         } else if let Some(version_range) =
-            config.parse_name_value_directive(line, "ignore-llvm-version")
+            config.parse_name_value_directive(line, "ignore-llvm-version", path, line_number)
         {
             // Syntax is: "ignore-llvm-version: <version1> [- <version2>]"
             let (v_min, v_max) =
@@ -1931,7 +2029,7 @@ fn ignore_llvm(config: &Config, path: &Utf8Path, line: &str) -> IgnoreDecision {
                 }
             }
         } else if let Some(version_string) =
-            config.parse_name_value_directive(line, "exact-llvm-major-version")
+            config.parse_name_value_directive(line, "exact-llvm-major-version", path, line_number)
         {
             // Syntax is "exact-llvm-major-version: <version>"
             let version = extract_llvm_version(&version_string);
diff --git a/src/tools/compiletest/src/directives/auxiliary.rs b/src/tools/compiletest/src/directives/auxiliary.rs
index cdb75f6ffa9..7c1ed2e7006 100644
--- a/src/tools/compiletest/src/directives/auxiliary.rs
+++ b/src/tools/compiletest/src/directives/auxiliary.rs
@@ -3,6 +3,8 @@
 
 use std::iter;
 
+use camino::Utf8Path;
+
 use super::directives::{AUX_BIN, AUX_BUILD, AUX_CODEGEN_BACKEND, AUX_CRATE, PROC_MACRO};
 use crate::common::Config;
 
@@ -41,17 +43,42 @@ impl AuxProps {
 
 /// If the given test directive line contains an `aux-*` directive, parse it
 /// and update [`AuxProps`] accordingly.
-pub(super) fn parse_and_update_aux(config: &Config, ln: &str, aux: &mut AuxProps) {
+pub(super) fn parse_and_update_aux(
+    config: &Config,
+    ln: &str,
+    testfile: &Utf8Path,
+    line_number: usize,
+    aux: &mut AuxProps,
+) {
     if !(ln.starts_with("aux-") || ln.starts_with("proc-macro")) {
         return;
     }
 
-    config.push_name_value_directive(ln, AUX_BUILD, &mut aux.builds, |r| r.trim().to_string());
-    config.push_name_value_directive(ln, AUX_BIN, &mut aux.bins, |r| r.trim().to_string());
-    config.push_name_value_directive(ln, AUX_CRATE, &mut aux.crates, parse_aux_crate);
-    config
-        .push_name_value_directive(ln, PROC_MACRO, &mut aux.proc_macros, |r| r.trim().to_string());
-    if let Some(r) = config.parse_name_value_directive(ln, AUX_CODEGEN_BACKEND) {
+    config.push_name_value_directive(ln, AUX_BUILD, testfile, line_number, &mut aux.builds, |r| {
+        r.trim().to_string()
+    });
+    config.push_name_value_directive(ln, AUX_BIN, testfile, line_number, &mut aux.bins, |r| {
+        r.trim().to_string()
+    });
+    config.push_name_value_directive(
+        ln,
+        AUX_CRATE,
+        testfile,
+        line_number,
+        &mut aux.crates,
+        parse_aux_crate,
+    );
+    config.push_name_value_directive(
+        ln,
+        PROC_MACRO,
+        testfile,
+        line_number,
+        &mut aux.proc_macros,
+        |r| r.trim().to_string(),
+    );
+    if let Some(r) =
+        config.parse_name_value_directive(ln, AUX_CODEGEN_BACKEND, testfile, line_number)
+    {
         aux.codegen_backend = Some(r.trim().to_owned());
     }
 }
diff --git a/src/tools/compiletest/src/runtest/debugger.rs b/src/tools/compiletest/src/runtest/debugger.rs
index a4103c5b4a9..ba824124e87 100644
--- a/src/tools/compiletest/src/runtest/debugger.rs
+++ b/src/tools/compiletest/src/runtest/debugger.rs
@@ -47,10 +47,14 @@ impl DebuggerCommands {
                 continue;
             };
 
-            if let Some(command) = config.parse_name_value_directive(&line, &command_directive) {
+            if let Some(command) =
+                config.parse_name_value_directive(&line, &command_directive, file, line_no)
+            {
                 commands.push(command);
             }
-            if let Some(pattern) = config.parse_name_value_directive(&line, &check_directive) {
+            if let Some(pattern) =
+                config.parse_name_value_directive(&line, &check_directive, file, line_no)
+            {
                 check_lines.push((line_no, pattern));
             }
         }
diff --git a/src/tools/tidy/src/style.rs b/src/tools/tidy/src/style.rs
index 35ed61eacc7..fca097c091b 100644
--- a/src/tools/tidy/src/style.rs
+++ b/src/tools/tidy/src/style.rs
@@ -519,8 +519,11 @@ pub fn check(path: &Path, bad: &mut bool) {
                         .any(|directive| matches!(directive, Directive::Ignore(_)));
                 let has_alphabetical_directive = line.contains("tidy-alphabetical-start")
                     || line.contains("tidy-alphabetical-end");
-                let has_recognized_directive =
-                    has_recognized_ignore_directive || has_alphabetical_directive;
+                let has_other_tidy_ignore_directive =
+                    line.contains("ignore-tidy-target-specific-tests");
+                let has_recognized_directive = has_recognized_ignore_directive
+                    || has_alphabetical_directive
+                    || has_other_tidy_ignore_directive;
                 if contains_potential_directive && (!has_recognized_directive) {
                     err("Unrecognized tidy directive")
                 }
diff --git a/src/tools/tidy/src/target_specific_tests.rs b/src/tools/tidy/src/target_specific_tests.rs
index f4a6783abb6..b2d5f259eb2 100644
--- a/src/tools/tidy/src/target_specific_tests.rs
+++ b/src/tools/tidy/src/target_specific_tests.rs
@@ -12,12 +12,16 @@ const COMPILE_FLAGS_HEADER: &str = "compile-flags:";
 
 #[derive(Default, Debug)]
 struct RevisionInfo<'a> {
-    target_arch: Option<&'a str>,
+    target_arch: Option<Option<&'a str>>,
     llvm_components: Option<Vec<&'a str>>,
 }
 
 pub fn check(tests_path: &Path, bad: &mut bool) {
     crate::walk::walk(tests_path, |path, _is_dir| filter_not_rust(path), &mut |entry, content| {
+        if content.contains("// ignore-tidy-target-specific-tests") {
+            return;
+        }
+
         let file = entry.path().display();
         let mut header_map = BTreeMap::new();
         iter_header(content, &mut |HeaderLine { revision, directive, .. }| {
@@ -34,10 +38,11 @@ pub fn check(tests_path: &Path, bad: &mut bool) {
                 && let Some((_, v)) = compile_flags.split_once("--target")
             {
                 let v = v.trim_start_matches([' ', '=']);
-                let v = if v == "{{target}}" { Some((v, v)) } else { v.split_once("-") };
-                if let Some((arch, _)) = v {
-                    let info = header_map.entry(revision).or_insert(RevisionInfo::default());
-                    info.target_arch.replace(arch);
+                let info = header_map.entry(revision).or_insert(RevisionInfo::default());
+                if v.starts_with("{{") {
+                    info.target_arch.replace(None);
+                } else if let Some((arch, _)) = v.split_once("-") {
+                    info.target_arch.replace(Some(arch));
                 } else {
                     eprintln!("{file}: seems to have a malformed --target value");
                     *bad = true;
@@ -54,9 +59,11 @@ pub fn check(tests_path: &Path, bad: &mut bool) {
             let rev = rev.unwrap_or("[unspecified]");
             match (target_arch, llvm_components) {
                 (None, None) => {}
-                (Some(_), None) => {
+                (Some(target_arch), None) => {
+                    let llvm_component =
+                        target_arch.map_or_else(|| "<arch>".to_string(), arch_to_llvm_component);
                     eprintln!(
-                        "{file}: revision {rev} should specify `{LLVM_COMPONENTS_HEADER}` as it has `--target` set"
+                        "{file}: revision {rev} should specify `{LLVM_COMPONENTS_HEADER} {llvm_component}` as it has `--target` set"
                     );
                     *bad = true;
                 }
@@ -66,11 +73,45 @@ pub fn check(tests_path: &Path, bad: &mut bool) {
                     );
                     *bad = true;
                 }
-                (Some(_), Some(_)) => {
-                    // FIXME: check specified components against the target architectures we
-                    // gathered.
+                (Some(target_arch), Some(llvm_components)) => {
+                    if let Some(target_arch) = target_arch {
+                        let llvm_component = arch_to_llvm_component(target_arch);
+                        if !llvm_components.contains(&llvm_component.as_str()) {
+                            eprintln!(
+                                "{file}: revision {rev} should specify `{LLVM_COMPONENTS_HEADER} {llvm_component}` as it has `--target` set"
+                            );
+                            *bad = true;
+                        }
+                    }
                 }
             }
         }
     });
 }
+
+fn arch_to_llvm_component(arch: &str) -> String {
+    // NOTE: This is an *approximate* mapping of Rust's `--target` architecture to LLVM component
+    // names. It is not intended to be an authoritative source, but rather a best-effort that's good
+    // enough for the purpose of this tidy check.
+    match arch {
+        "amdgcn" => "amdgpu".into(),
+        "aarch64_be" | "arm64_32" | "arm64e" | "arm64ec" => "aarch64".into(),
+        "i386" | "i586" | "i686" | "x86" | "x86_64" | "x86_64h" => "x86".into(),
+        "loongarch32" | "loongarch64" => "loongarch".into(),
+        "nvptx64" => "nvptx".into(),
+        "s390x" => "systemz".into(),
+        "sparc64" | "sparcv9" => "sparc".into(),
+        "wasm32" | "wasm32v1" | "wasm64" => "webassembly".into(),
+        _ if arch.starts_with("armeb")
+            || arch.starts_with("armv")
+            || arch.starts_with("thumbv") =>
+        {
+            "arm".into()
+        }
+        _ if arch.starts_with("bpfe") => "bpf".into(),
+        _ if arch.starts_with("mips") => "mips".into(),
+        _ if arch.starts_with("powerpc") => "powerpc".into(),
+        _ if arch.starts_with("riscv") => "riscv".into(),
+        _ => arch.to_ascii_lowercase(),
+    }
+}