Add target.*.runner configuration for targets

This commit adds a `runner` field configuration to `config.toml` for
specifying a wrapper executable when executing binaries for a target.
This is pulled out of #122036 where a WebAssembly runtime is used, for
example, to execute tests for `wasm32-wasip1`.

The name "runner" here is chosen to match Cargo's `CARGO_*_RUNNER`
configuration, and to make things a bit more consistent this
additionally renames compiletest's `--runtool` argument to `--runner`.

config.example.toml

@@ -842,6 +842,17 @@
 # See that option for more info.
 #codegen-backends = rust.codegen-backends (array)
 
+# This is a "runner" to pass to `compiletest` when executing tests. Tests will
+# execute this tool where the binary-to-test is passed as an argument. Can
+# be useful for situations such as when WebAssembly is being tested and a
+# runtime needs to be configured. This value is similar to
+# Cargo's `CARGO_$target_RUNNER` configuration.
+#
+# This configuration is a space-separated list of arguments so `foo bar` would
+# execute the program `foo` with the first argument as `bar` and the second
+# argument as the test binary.
+#runner = <none> (string)
+
 # =============================================================================
 # Distribution options
 #

src/bootstrap/src/core/build_steps/test.rs

@@ -1970,6 +1970,8 @@ NOTE: if you're sure you want to do this, please open an issue as to why. In the
 
         if builder.remote_tested(target) {
             cmd.arg("--remote-test-client").arg(builder.tool_exe(Tool::RemoteTestClient));
+        } else if let Some(tool) = builder.runner(target) {
+            cmd.arg("--runner").arg(tool);
         }
 
         if suite != "mir-opt" {
@@ -2519,6 +2521,8 @@ fn prepare_cargo_test(
             format!("CARGO_TARGET_{}_RUNNER", envify(&target.triple)),
             format!("{} run 0", builder.tool_exe(Tool::RemoteTestClient).display()),
         );
+    } else if let Some(tool) = builder.runner(target) {
+        cargo.env(format!("CARGO_TARGET_{}_RUNNER", envify(&target.triple)), tool);
     }
 
     cargo

src/bootstrap/src/core/config/config.rs

@@ -579,6 +579,7 @@ pub struct Target {
     pub musl_libdir: Option<PathBuf>,
     pub wasi_root: Option<PathBuf>,
     pub qemu_rootfs: Option<PathBuf>,
+    pub runner: Option<String>,
     pub no_std: bool,
     pub codegen_backends: Option<Vec<Interned<String>>>,
 }
@@ -1142,6 +1143,7 @@ define_config! {
         qemu_rootfs: Option<String> = "qemu-rootfs",
         no_std: Option<bool> = "no-std",
         codegen_backends: Option<Vec<String>> = "codegen-backends",
+        runner: Option<String> = "runner",
     }
 }
 
@@ -1862,6 +1864,7 @@ impl Config {
                 target.musl_libdir = cfg.musl_libdir.map(PathBuf::from);
                 target.wasi_root = cfg.wasi_root.map(PathBuf::from);
                 target.qemu_rootfs = cfg.qemu_rootfs.map(PathBuf::from);
+                target.runner = cfg.runner;
                 target.sanitizers = cfg.sanitizers;
                 target.profiler = cfg.profiler;
                 target.rpath = cfg.rpath;

src/bootstrap/src/lib.rs

@@ -1353,6 +1353,17 @@ impl Build {
             || env::var_os("TEST_DEVICE_ADDR").is_some()
     }
 
+    /// Returns an optional "runner" to pass to `compiletest` when executing
+    /// test binaries.
+    ///
+    /// An example of this would be a WebAssembly runtime when testing the wasm
+    /// targets.
+    fn runner(&self, target: TargetSelection) -> Option<String> {
+        let target = self.config.target_config.get(&target)?;
+        let runner = target.runner.as_ref()?;
+        Some(runner.to_owned())
+    }
+
     /// Returns the root of the "rootfs" image that this target will be using,
     /// if one was configured.
     ///

src/tools/compiletest/src/common.rs

@@ -266,8 +266,10 @@ pub struct Config {
     pub logfile: Option<PathBuf>,
 
     /// A command line to prefix program execution with,
-    /// for running under valgrind
+    /// for running under valgrind for example.
-    pub runtool: Option<String>,
+    ///
+    /// Similar to `CARGO_*_RUNNER` configuration.
+    pub runner: Option<String>,
 
     /// Flags to pass to the compiler when building for the host
     pub host_rustcflags: Vec<String>,

src/tools/compiletest/src/lib.rs

@@ -86,7 +86,7 @@ pub fn parse_config(args: Vec<String>) -> Config {
         .optflag("", "exact", "filters match exactly")
         .optopt(
             "",
-            "runtool",
+            "runner",
             "supervisor program to run tests under \
              (eg. emulator, valgrind)",
             "PROGRAM",
@@ -256,7 +256,7 @@ pub fn parse_config(args: Vec<String>) -> Config {
             _ => panic!("unknown `--run` option `{}` given", mode),
         }),
         logfile: matches.opt_str("logfile").map(|s| PathBuf::from(&s)),
-        runtool: matches.opt_str("runtool"),
+        runner: matches.opt_str("runner"),
         host_rustcflags: matches.opt_strs("host-rustcflags"),
         target_rustcflags: matches.opt_strs("target-rustcflags"),
         optimize_tests: matches.opt_present("optimize-tests"),
@@ -341,7 +341,7 @@ pub fn log_config(config: &Config) {
         c,
         format!("force_pass_mode: {}", opt_str(&config.force_pass_mode.map(|m| format!("{}", m))),),
     );
-    logv(c, format!("runtool: {}", opt_str(&config.runtool)));
+    logv(c, format!("runner: {}", opt_str(&config.runner)));
     logv(c, format!("host-rustcflags: {:?}", config.host_rustcflags));
     logv(c, format!("target-rustcflags: {:?}", config.target_rustcflags));
     logv(c, format!("target: {}", config.target));

src/tools/compiletest/src/runtest.rs

@@ -461,7 +461,7 @@ impl<'test> TestCx<'test> {
         }
 
         let mut new_config = self.config.clone();
-        new_config.runtool = new_config.valgrind_path.clone();
+        new_config.runner = new_config.valgrind_path.clone();
         let new_cx = TestCx { config: &new_config, ..*self };
         proc_res = new_cx.exec_compiled_test();
 
@@ -2647,7 +2647,7 @@ impl<'test> TestCx<'test> {
     fn make_run_args(&self) -> ProcArgs {
         // If we've got another tool to run under (valgrind),
         // then split apart its command
-        let mut args = self.split_maybe_args(&self.config.runtool);
+        let mut args = self.split_maybe_args(&self.config.runner);
 
         // If this is emscripten, then run tests under nodejs
         if self.config.target.contains("emscripten") {