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`.

1 files changed, 11 insertions, 0 deletions

diff --git a/config.example.toml b/config.example.toml
index c1939933850..4fbdccba911 100644
--- a/config.example.toml
+++ b/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
 #