Allow tests to ignore individual test modes

Normally, each test in `tests/coverage` is automatically run in both
`coverage-map` mode and `coverage-run` mode.

This new family of directives allows an individual test to specify that it
should not be run in a particular mode.

src/tools/compiletest/src/header/cfg.rs

@@ -1,4 +1,4 @@
-use crate::common::{CompareMode, Config, Debugger};
+use crate::common::{CompareMode, Config, Debugger, Mode};
 use crate::header::IgnoreDecision;
 use std::collections::HashSet;
 
@@ -208,6 +208,17 @@ pub(super) fn parse_cfg_name_directive<'a>(
         },
         message: "when comparing with {name}",
     }
+    // Coverage tests run the same test file in multiple modes.
+    // If a particular test should not be run in one of the modes, ignore it
+    // with "ignore-mode-coverage-map" or "ignore-mode-coverage-run".
+    condition! {
+        name: format!("mode-{}", config.mode.to_str()),
+        allowed_names: ContainsPrefixed {
+            prefix: "mode-",
+            inner: Mode::STR_VARIANTS,
+        },
+        message: "when the test mode is {name}",
+    }
 
     if prefix == "ignore" && outcome == MatchOutcome::Invalid {
         // Don't error out for ignore-tidy-* diretives, as those are not handled by compiletest.

src/tools/compiletest/src/header/tests.rs

@@ -1,7 +1,8 @@
 use std::io::Read;
 use std::path::Path;
+use std::str::FromStr;
 
-use crate::common::{Config, Debugger};
+use crate::common::{Config, Debugger, Mode};
 use crate::header::{parse_normalization_string, EarlyProps, HeadersCache};
 
 fn make_test_description<R: Read>(
@@ -55,6 +56,7 @@ fn test_parse_normalization_string() {
 
 #[derive(Default)]
 struct ConfigBuilder {
+    mode: Option<String>,
     channel: Option<String>,
     host: Option<String>,
     target: Option<String>,
@@ -66,6 +68,11 @@ struct ConfigBuilder {
 }
 
 impl ConfigBuilder {
+    fn mode(&mut self, s: &str) -> &mut Self {
+        self.mode = Some(s.to_owned());
+        self
+    }
+
     fn channel(&mut self, s: &str) -> &mut Self {
         self.channel = Some(s.to_owned());
         self
@@ -109,7 +116,8 @@ impl ConfigBuilder {
     fn build(&mut self) -> Config {
         let args = &[
             "compiletest",
-            "--mode=ui",
+            "--mode",
+            self.mode.as_deref().unwrap_or("ui"),
             "--suite=ui",
             "--compile-lib-path=",
             "--run-lib-path=",
@@ -548,3 +556,17 @@ fn families() {
         assert!(!check_ignore(&config, &format!("// ignore-{other}")));
     }
 }
+
+#[test]
+fn ignore_mode() {
+    for &mode in Mode::STR_VARIANTS {
+        // Indicate profiler support so that "coverage-run" tests aren't skipped.
+        let config: Config = cfg().mode(mode).profiler_support(true).build();
+        let other = if mode == "coverage-run" { "coverage-map" } else { "coverage-run" };
+        assert_ne!(mode, other);
+        assert_eq!(config.mode, Mode::from_str(mode).unwrap());
+        assert_ne!(config.mode, Mode::from_str(other).unwrap());
+        assert!(check_ignore(&config, &format!("// ignore-mode-{mode}")));
+        assert!(!check_ignore(&config, &format!("// ignore-mode-{other}")));
+    }
+}

tests/coverage/ignore_map.coverage

@@ -0,0 +1,4 @@
+   LL|       |// ignore-mode-coverage-map
+   LL|       |
+   LL|      1|fn main() {}
+

tests/coverage/ignore_map.rs

@@ -0,0 +1,3 @@
+// ignore-mode-coverage-map
+
+fn main() {}

tests/coverage/ignore_run.cov-map

@@ -0,0 +1,8 @@
+Function name: ignore_run::main
+Raw bytes (9): 0x[01, 01, 00, 01, 01, 03, 01, 00, 0d]
+Number of files: 1
+- file 0 => global file 1
+Number of expressions: 0
+Number of file 0 mappings: 1
+- Code(Counter(0)) at (prev + 3, 1) to (start + 0, 13)
+

tests/coverage/ignore_run.rs

@@ -0,0 +1,3 @@
+// ignore-mode-coverage-run
+
+fn main() {}