Auto merge of #132152 - lqd:revert-127731, r=compiler-errors

Revert #127731 "Emit error when calling/declaring functions with unavailable …"

This reverts #127731 due to the unexpected [perf regressions](#127731 (comment)) and to give time to mitigate the regressions before re-landing it.

r? `@RalfJung` cc `@veluca93`

Author: bors

compiler/rustc_lint_defs/src/builtin.rs

@@ -16,7 +16,6 @@ declare_lint_pass! {
     /// that are used by other parts of the compiler.
     HardwiredLints => [
         // tidy-alphabetical-start
-        ABI_UNSUPPORTED_VECTOR_TYPES,
         ABSOLUTE_PATHS_NOT_STARTING_WITH_CRATE,
         AMBIGUOUS_ASSOCIATED_ITEMS,
         AMBIGUOUS_GLOB_IMPORTS,
@@ -5029,69 +5028,3 @@ declare_lint! {
     };
     crate_level_only
 }
-
-declare_lint! {
-    /// The `abi_unsupported_vector_types` lint detects function definitions and calls
-    /// whose ABI depends on enabling certain target features, but those features are not enabled.
-    ///
-    /// ### Example
-    ///
-    /// ```rust,ignore (fails on non-x86_64)
-    /// extern "C" fn missing_target_feature(_: std::arch::x86_64::__m256) {
-    ///   todo!()
-    /// }
-    ///
-    /// #[target_feature(enable = "avx")]
-    /// unsafe extern "C" fn with_target_feature(_: std::arch::x86_64::__m256) {
-    ///   todo!()
-    /// }
-    ///
-    /// fn main() {
-    ///   let v = unsafe { std::mem::zeroed() };
-    ///   unsafe { with_target_feature(v); }
-    /// }
-    /// ```
-    ///
-    /// ```text
-    /// warning: ABI error: this function call uses a avx vector type, which is not enabled in the caller
-    ///  --> lint_example.rs:18:12
-    ///   |
-    ///   |   unsafe { with_target_feature(v); }
-    ///   |            ^^^^^^^^^^^^^^^^^^^^^^ function called here
-    ///   |
-    ///   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
-    ///   = note: for more information, see issue #116558 <https://github.com/rust-lang/rust/issues/116558>
-    ///   = help: consider enabling it globally (-C target-feature=+avx) or locally (#[target_feature(enable="avx")])
-    ///   = note: `#[warn(abi_unsupported_vector_types)]` on by default
-    ///
-    ///
-    /// warning: ABI error: this function definition uses a avx vector type, which is not enabled
-    ///  --> lint_example.rs:3:1
-    ///   |
-    ///   | pub extern "C" fn with_target_feature(_: std::arch::x86_64::__m256) {
-    ///   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ function defined here
-    ///   |
-    ///   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
-    ///   = note: for more information, see issue #116558 <https://github.com/rust-lang/rust/issues/116558>
-    ///   = help: consider enabling it globally (-C target-feature=+avx) or locally (#[target_feature(enable="avx")])
-    /// ```
-    ///
-    ///
-    ///
-    /// ### Explanation
-    ///
-    /// The C ABI for `__m256` requires the value to be passed in an AVX register,
-    /// which is only possible when the `avx` target feature is enabled.
-    /// Therefore, `missing_target_feature` cannot be compiled without that target feature.
-    /// A similar (but complementary) message is triggered when `with_target_feature` is called
-    /// by a function that does not enable the `avx` target feature.
-    ///
-    /// Note that this lint is very similar to the `-Wpsabi` warning in `gcc`/`clang`.
-    pub ABI_UNSUPPORTED_VECTOR_TYPES,
-    Warn,
-    "this function call or definition uses a vector type which is not enabled",
-    @future_incompatible = FutureIncompatibleInfo {
-        reason: FutureIncompatibilityReason::FutureReleaseErrorDontReportInDeps,
-        reference: "issue #116558 <https://github.com/rust-lang/rust/issues/116558>",
-    };
-}

compiler/rustc_monomorphize/messages.ftl

@@ -1,12 +1,3 @@
-monomorphize_abi_error_disabled_vector_type_call =
-  ABI error: this function call uses a vector type that requires the `{$required_feature}` target feature, which is not enabled in the caller
-  .label = function called here
-  .help = consider enabling it globally (`-C target-feature=+{$required_feature}`) or locally (`#[target_feature(enable="{$required_feature}")]`)
-monomorphize_abi_error_disabled_vector_type_def =
-  ABI error: this function definition uses a vector type that requires the `{$required_feature}` target feature, which is not enabled
-  .label = function defined here
-  .help = consider enabling it globally (`-C target-feature=+{$required_feature}`) or locally (`#[target_feature(enable="{$required_feature}")]`)
-
 monomorphize_couldnt_dump_mono_stats =
     unexpected error occurred while dumping monomorphization stats: {$error}
 

compiler/rustc_monomorphize/src/collector.rs

@@ -205,7 +205,6 @@
 //! this is not implemented however: a mono item will be produced
 //! regardless of whether it is actually needed or not.
 
-mod abi_check;
 mod move_check;
 
 use std::path::PathBuf;
@@ -767,7 +766,6 @@ impl<'a, 'tcx> MirVisitor<'tcx> for MirUsedCollector<'a, 'tcx> {
                 self.used_mentioned_items.insert(MentionedItem::Fn(callee_ty));
                 let callee_ty = self.monomorphize(callee_ty);
                 self.check_fn_args_move_size(callee_ty, args, *fn_span, location);
-                abi_check::check_call_site_abi(tcx, callee_ty, *fn_span, self.body.source.instance);
                 visit_fn_use(self.tcx, callee_ty, true, source, &mut self.used_items)
             }
             mir::TerminatorKind::Drop { ref place, .. } => {
@@ -1209,9 +1207,6 @@ fn collect_items_of_instance<'tcx>(
     mentioned_items: &mut MonoItems<'tcx>,
     mode: CollectionMode,
 ) {
-    // Check the instance for feature-dependent ABI.
-    abi_check::check_instance_abi(tcx, instance);
-
     let body = tcx.instance_mir(instance.def);
     // Naively, in "used" collection mode, all functions get added to *both* `used_items` and
     // `mentioned_items`. Mentioned items processing will then notice that they have already been

compiler/rustc_monomorphize/src/collector/abi_check.rs

@@ -92,21 +92,3 @@ pub(crate) struct StartNotFound;
 pub(crate) struct UnknownCguCollectionMode<'a> {
     pub mode: &'a str,
 }
-
-#[derive(LintDiagnostic)]
-#[diag(monomorphize_abi_error_disabled_vector_type_def)]
-#[help]
-pub(crate) struct AbiErrorDisabledVectorTypeDef<'a> {
-    #[label]
-    pub span: Span,
-    pub required_feature: &'a str,
-}
-
-#[derive(LintDiagnostic)]
-#[diag(monomorphize_abi_error_disabled_vector_type_call)]
-#[help]
-pub(crate) struct AbiErrorDisabledVectorTypeCall<'a> {
-    #[label]
-    pub span: Span,
-    pub required_feature: &'a str,
-}

compiler/rustc_monomorphize/src/errors.rs

@@ -522,13 +522,6 @@ pub fn all_known_features() -> impl Iterator<Item = (&'static str, Stability)> {
         .map(|(f, s, _)| (f, s))
 }
 
-// These arrays represent the least-constraining feature that is required for vector types up to a
-// certain size to have their "proper" ABI on each architecture.
-// Note that they must be kept sorted by vector size.
-const X86_FEATURES_FOR_CORRECT_VECTOR_ABI: &'static [(u64, &'static str)] =
-    &[(128, "sse"), (256, "avx"), (512, "avx512f")];
-const AARCH64_FEATURES_FOR_CORRECT_VECTOR_ABI: &'static [(u64, &'static str)] = &[(128, "neon")];
-
 impl super::spec::Target {
     pub fn supported_target_features(
         &self,
@@ -550,16 +543,6 @@ impl super::spec::Target {
         }
     }
 
-    // Returns None if we do not support ABI checks on the given target yet.
-    pub fn features_for_correct_vector_abi(&self) -> Option<&'static [(u64, &'static str)]> {
-        match &*self.arch {
-            "x86" | "x86_64" => Some(X86_FEATURES_FOR_CORRECT_VECTOR_ABI),
-            "aarch64" => Some(AARCH64_FEATURES_FOR_CORRECT_VECTOR_ABI),
-            // FIXME: add support for non-tier1 architectures
-            _ => None,
-        }
-    }
-
     pub fn tied_target_features(&self) -> &'static [&'static [&'static str]] {
         match &*self.arch {
             "aarch64" | "arm64ec" => AARCH64_TIED_FEATURES,

compiler/rustc_target/src/target_features.rs

@@ -0,0 +1,40 @@
+//@ known-bug: #131342
+// see also: 131342.rs
+
+fn main() {
+    problem_thingy(Once);
+}
+
+struct Once;
+
+impl Iterator for Once {
+    type Item = ();
+}
+
+fn problem_thingy(items: impl Iterator) {
+    let peeker = items.peekable();
+    problem_thingy(&peeker);
+}
+
+trait Iterator {
+    type Item;
+
+    fn peekable(self) -> Peekable<Self>
+    where
+        Self: Sized,
+    {
+        loop {}
+    }
+}
+
+struct Peekable<I: Iterator> {
+    _peeked: I::Item,
+}
+
+impl<I: Iterator> Iterator for Peekable<I> {
+    type Item = I::Item;
+}
+
+impl<I: Iterator + ?Sized> Iterator for &I {
+    type Item = I::Item;
+}

tests/crashes/131342-2.rs

@@ -1,4 +1,5 @@
 //@ known-bug: #131342
+// see also: 131342-2.rs
 
 fn main() {
   let mut items = vec![1, 2, 3, 4, 5].into_iter();

tests/crashes/131342.rs

@@ -45,6 +45,7 @@ where
     T: Blah,
 {
     async fn ice(&mut self) {
+        //~^ ERROR a cycle occurred during layout computation
         let arr: [(); 0] = [];
         self.t.iter(arr.into_iter()).await;
     }

tests/ui/layout/post-mono-layout-cycle-2.rs

@@ -12,12 +12,12 @@ LL |           Blah::iter(self, iterator).await
    |
    = note: a recursive `async fn` call must introduce indirection such as `Box::pin` to avoid an infinitely sized future
 
-note: the above error was encountered while instantiating `fn main::{closure#0}`
-  --> $DIR/post-mono-layout-cycle-2.rs:16:15
+error: a cycle occurred during layout computation
+  --> $DIR/post-mono-layout-cycle-2.rs:47:5
    |
-LL |         match fut.as_mut().poll(ctx) {
-   |               ^^^^^^^^^^^^^^^^^^^^^^
+LL |     async fn ice(&mut self) {
+   |     ^^^^^^^^^^^^^^^^^^^^^^^
 
-error: aborting due to 1 previous error
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0733`.