Rollup merge of #136147 - RalfJung:required-target-features-check-not-add, r=workingjubilee

ABI-required target features: warn when they are missing in base CPU

Part of https://github.com/rust-lang/rust/pull/135408:
instead of adding ABI-required features to the target we build for LLVM, check that they are already there. Crucially we check this after applying `-Ctarget-cpu` and `-Ctarget-feature`, by reading `sess.unstable_target_features`. This means we can tweak the ABI target feature check without changing the behavior for any existing user; they will get warnings but the target features behave as before.

The test changes here show that we are un-doing the "add all required target features" part. Without the full #135408, there is no way to take a way an ABI-required target feature with `-Ctarget-cpu`, so we cannot yet test that part.

Cc ``@workingjubilee``

1 files changed, 9 insertions, 0 deletions

diff --git a/compiler/rustc_interface/src/errors.rs b/compiler/rustc_interface/src/errors.rs
index 939980a932f..b62950d6709 100644
--- a/compiler/rustc_interface/src/errors.rs
+++ b/compiler/rustc_interface/src/errors.rs
@@ -103,3 +103,12 @@ pub struct IgnoringOutDir;
 #[derive(Diagnostic)]
 #[diag(interface_multiple_output_types_to_stdout)]
 pub struct MultipleOutputTypesToStdout;
+
+#[derive(Diagnostic)]
+#[diag(interface_abi_required_feature)]
+#[note]
+#[note(interface_abi_required_feature_issue)]
+pub(crate) struct AbiRequiredTargetFeature<'a> {
+    pub feature: &'a str,
+    pub enabled: &'a str,
+}