Emit an error if -Z instrument-xray is not supported

This is somewhat important because LLVM enables the pass based on
target architecture, but support by the target OS also matters.

For example, XRay attributes are processed by codegen for macOS
targets, but Apple linker fails to process relocations in XRay
data sections, so the feature as a whole is not supported there
for the time being.

2 files changed, 10 insertions, 0 deletions

diff --git a/compiler/rustc_session/src/errors.rs b/compiler/rustc_session/src/errors.rs
index 8e8fba5e236..c851145440b 100644
--- a/compiler/rustc_session/src/errors.rs
+++ b/compiler/rustc_session/src/errors.rs
@@ -72,6 +72,12 @@ pub struct ProfileSampleUseFileDoesNotExist<'a> {
 pub struct TargetRequiresUnwindTables;
 
 #[derive(Diagnostic)]
+#[diag(session_instrumentation_not_supported)]
+pub struct InstrumentationNotSupported {
+    pub us: String,
+}
+
+#[derive(Diagnostic)]
 #[diag(session_sanitizer_not_supported)]
 pub struct SanitizerNotSupported {
     pub us: String,
diff --git a/compiler/rustc_session/src/session.rs b/compiler/rustc_session/src/session.rs
index 8a0176f6391..fe6ac80fde6 100644
--- a/compiler/rustc_session/src/session.rs
+++ b/compiler/rustc_session/src/session.rs
@@ -1589,6 +1589,10 @@ fn validate_commandline_args_with_session_available(sess: &Session) {
     {
         sess.emit_err(errors::SplitDebugInfoUnstablePlatform { debuginfo: sess.split_debuginfo() });
     }
+
+    if sess.opts.unstable_opts.instrument_xray.is_some() && !sess.target.options.supports_xray {
+        sess.emit_err(errors::InstrumentationNotSupported { us: "XRay".to_string() });
+    }
 }
 
 /// Holds data on the current incremental compilation session, if there is one.