From 3561dc948c1a2a24c2b49992099954a96be3c8ee Mon Sep 17 00:00:00 2001
From: Oleksii Lozovskyi <me@ilammy.net>
Date: Sun, 2 Oct 2022 10:55:35 +0900
Subject: [PATCH] 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.
---
 compiler/rustc_error_messages/locales/en-US/session.ftl | 2 ++
 compiler/rustc_session/src/errors.rs                    | 6 ++++++
 compiler/rustc_session/src/session.rs                   | 4 ++++
 tests/ui/instrument-xray/target-not-supported.rs        | 9 +++++++++
 tests/ui/instrument-xray/target-not-supported.stderr    | 4 ++++
 5 files changed, 25 insertions(+)
 create mode 100644 tests/ui/instrument-xray/target-not-supported.rs
 create mode 100644 tests/ui/instrument-xray/target-not-supported.stderr

diff --git a/compiler/rustc_error_messages/locales/en-US/session.ftl b/compiler/rustc_error_messages/locales/en-US/session.ftl
index 5984c201af0..fe553edab42 100644
--- a/compiler/rustc_error_messages/locales/en-US/session.ftl
+++ b/compiler/rustc_error_messages/locales/en-US/session.ftl
@@ -25,6 +25,8 @@ session_profile_sample_use_file_does_not_exist = file `{$path}` passed to `-C pr
 
 session_target_requires_unwind_tables = target requires unwind tables, they cannot be disabled with `-C force-unwind-tables=no`
 
+session_instrumentation_not_supported = {$us} instrumentation is not supported for this target
+
 session_sanitizer_not_supported = {$us} sanitizer is not supported for this target
 
 session_sanitizers_not_supported = {$us} sanitizers are not supported for this target
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
@@ -71,6 +71,12 @@ pub struct ProfileSampleUseFileDoesNotExist<'a> {
 #[diag(session_target_requires_unwind_tables)]
 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 {
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.
diff --git a/tests/ui/instrument-xray/target-not-supported.rs b/tests/ui/instrument-xray/target-not-supported.rs
new file mode 100644
index 00000000000..e6bdd23e8fc
--- /dev/null
+++ b/tests/ui/instrument-xray/target-not-supported.rs
@@ -0,0 +1,9 @@
+// Verifies that `-Z instrument-xray` cannot be used with unsupported targets,
+//
+// needs-llvm-components: x86
+// compile-flags: -Z instrument-xray --target x86_64-apple-darwin
+// error-pattern: error: XRay instrumentation is not supported for this target
+
+#![feature(no_core)]
+#![no_core]
+#![no_main]
diff --git a/tests/ui/instrument-xray/target-not-supported.stderr b/tests/ui/instrument-xray/target-not-supported.stderr
new file mode 100644
index 00000000000..6e3b0c8a380
--- /dev/null
+++ b/tests/ui/instrument-xray/target-not-supported.stderr
@@ -0,0 +1,4 @@
+error: XRay instrumentation is not supported for this target
+
+error: aborting due to previous error
+