Auto merge of #129935 - RalfJung:unsupported_calling_conventions, r=

make unsupported_calling_conventions a hard error This has been a future-compat lint (not shown in dependencies) since Rust 1.55, released 3 years ago. Hopefully that was enough time so this can be made a hard error now. Given that long timeframe, I think it's justified to skip the "show in dependencies" stage. There were [not many crates hitting this](#86231 (comment)) even when the PR was landed. This should get cratered, and I assume then it needs a t-compiler FCP. Fixes #88397
rust-lang · Sep 3, 2024 · 498fce2 · 498fce2
2 parents d6c8169 + 0c5a9b3
commit 498fce2
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diff --git a/compiler/rustc_hir_analysis/src/check/check.rs b/compiler/rustc_hir_analysis/src/check/check.rs
@@ -20,7 +20,7 @@ use rustc_middle::ty::{
     AdtDef, GenericArgKind, ParamEnv, RegionKind, TypeSuperVisitable, TypeVisitable,
     TypeVisitableExt,
 };
-use rustc_session::lint::builtin::{UNINHABITED_STATIC, UNSUPPORTED_CALLING_CONVENTIONS};
+use rustc_session::lint::builtin::UNINHABITED_STATIC;
 use rustc_target::abi::FieldIdx;
 use rustc_trait_selection::error_reporting::traits::on_unimplemented::OnUnimplementedDirective;
 use rustc_trait_selection::error_reporting::InferCtxtErrorExt;
@@ -34,23 +34,15 @@ use super::compare_impl_item::{check_type_bounds, compare_impl_method, compare_i
 use super::*;
 use crate::check::intrinsicck::InlineAsmCtxt;
 
-pub fn check_abi(tcx: TyCtxt<'_>, hir_id: hir::HirId, span: Span, abi: Abi) {
-    match tcx.sess.target.is_abi_supported(abi) {
-        Some(true) => (),
-        Some(false) => {
-            struct_span_code_err!(
-                tcx.dcx(),
-                span,
-                E0570,
-                "`{abi}` is not a supported ABI for the current target",
-            )
-            .emit();
-        }
-        None => {
-            tcx.node_span_lint(UNSUPPORTED_CALLING_CONVENTIONS, hir_id, span, |lint| {
-                lint.primary_message("use of calling convention not supported on this target");
-            });
-        }
+pub fn check_abi(tcx: TyCtxt<'_>, span: Span, abi: Abi) {
+    if !tcx.sess.target.is_abi_supported(abi) {
+        struct_span_code_err!(
+            tcx.dcx(),
+            span,
+            E0570,
+            "`{abi}` is not a supported ABI for the current target",
+        )
+        .emit();
     }
 
     // This ABI is only allowed on function pointers
@@ -754,7 +746,7 @@ pub(crate) fn check_item_type(tcx: TyCtxt<'_>, def_id: LocalDefId) {
             let hir::ItemKind::ForeignMod { abi, items } = it.kind else {
                 return;
             };
-            check_abi(tcx, it.hir_id(), it.span, abi);
+            check_abi(tcx, it.span, abi);
 
             match abi {
                 Abi::RustIntrinsic => {

diff --git a/compiler/rustc_hir_typeck/src/lib.rs b/compiler/rustc_hir_typeck/src/lib.rs
@@ -156,7 +156,7 @@ fn typeck_with_fallback<'tcx>(
             tcx.fn_sig(def_id).instantiate_identity()
         };
 
-        check_abi(tcx, id, span, fn_sig.abi());
+        check_abi(tcx, span, fn_sig.abi());
 
         // Compute the function signature from point of view of inside the fn.
         let fn_sig = tcx.liberate_late_bound_regions(def_id.to_def_id(), fn_sig);

diff --git a/compiler/rustc_lint/src/lib.rs b/compiler/rustc_lint/src/lib.rs
@@ -575,6 +575,7 @@ fn register_builtins(store: &mut LintStore) {
          <https://github.com/rust-lang/rust/issues/107457> for more information",
     );
     store.register_removed("writes_through_immutable_pointer", "converted into hard error");
+    store.register_removed("unsupported_calling_conventions", "converted into hard error");
 }
 
 fn register_internals(store: &mut LintStore) {

diff --git a/compiler/rustc_lint_defs/src/builtin.rs b/compiler/rustc_lint_defs/src/builtin.rs
@@ -124,7 +124,6 @@ declare_lint_pass! {
         UNSAFE_OP_IN_UNSAFE_FN,
         UNSTABLE_NAME_COLLISIONS,
         UNSTABLE_SYNTAX_PRE_EXPANSION,
-        UNSUPPORTED_CALLING_CONVENTIONS,
         UNUSED_ASSIGNMENTS,
         UNUSED_ASSOCIATED_TYPE_BOUNDS,
         UNUSED_ATTRIBUTES,
@@ -3922,53 +3921,6 @@ declare_lint! {
     crate_level_only
 }
 
-declare_lint! {
-    /// The `unsupported_calling_conventions` lint is output whenever there is a use of the
-    /// `stdcall`, `fastcall`, `thiscall`, `vectorcall` calling conventions (or their unwind
-    /// variants) on targets that cannot meaningfully be supported for the requested target.
-    ///
-    /// For example `stdcall` does not make much sense for a x86_64 or, more apparently, powerpc
-    /// code, because this calling convention was never specified for those targets.
-    ///
-    /// Historically MSVC toolchains have fallen back to the regular C calling convention for
-    /// targets other than x86, but Rust doesn't really see a similar need to introduce a similar
-    /// hack across many more targets.
-    ///
-    /// ### Example
-    ///
-    /// ```rust,ignore (needs specific targets)
-    /// extern "stdcall" fn stdcall() {}
-    /// ```
-    ///
-    /// This will produce:
-    ///
-    /// ```text
-    /// warning: use of calling convention not supported on this target
-    ///   --> $DIR/unsupported.rs:39:1
-    ///    |
-    /// LL | extern "stdcall" fn stdcall() {}
-    ///    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-    ///    |
-    ///    = note: `#[warn(unsupported_calling_conventions)]` on by default
-    ///    = 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 ...
-    /// ```
-    ///
-    /// ### Explanation
-    ///
-    /// On most of the targets the behaviour of `stdcall` and similar calling conventions is not
-    /// defined at all, but was previously accepted due to a bug in the implementation of the
-    /// compiler.
-    pub UNSUPPORTED_CALLING_CONVENTIONS,
-    Warn,
-    "use of unsupported calling convention",
-    @future_incompatible = FutureIncompatibleInfo {
-        reason: FutureIncompatibilityReason::FutureReleaseErrorDontReportInDeps,
-        reference: "issue #87678 <https://github.com/rust-lang/rust/issues/87678>",
-    };
-}
-
 declare_lint! {
     /// The `break_with_label_and_loop` lint detects labeled `break` expressions with
     /// an unlabeled loop as their value expression.

diff --git a/compiler/rustc_target/src/spec/mod.rs b/compiler/rustc_target/src/spec/mod.rs
@@ -2660,10 +2660,9 @@ impl Target {
         }
     }
 
-    /// Returns a None if the UNSUPPORTED_CALLING_CONVENTIONS lint should be emitted
-    pub fn is_abi_supported(&self, abi: Abi) -> Option<bool> {
+    pub fn is_abi_supported(&self, abi: Abi) -> bool {
         use Abi::*;
-        Some(match abi {
+        match abi {
             Rust
             | C { .. }
             | System { .. }
@@ -2719,9 +2718,9 @@ impl Target {
             // architectures for which these calling conventions are actually well defined.
             Stdcall { .. } | Fastcall { .. } if self.arch == "x86" => true,
             Vectorcall { .. } if ["x86", "x86_64"].contains(&&self.arch[..]) => true,
-            // Return a `None` for other cases so that we know to emit a future compat lint.
-            Stdcall { .. } | Fastcall { .. } | Vectorcall { .. } => return None,
-        })
+            // Reject these calling conventions everywhere else.
+            Stdcall { .. } | Fastcall { .. } | Vectorcall { .. } => false,
+        }
     }
 
     /// Minimum integer size in bits that this target can perform atomic

diff --git a/src/tools/clippy/tests/ui/missing_const_for_fn/could_be_const_with_const_extern_fn.rs b/src/tools/clippy/tests/ui/missing_const_for_fn/could_be_const_with_const_extern_fn.rs
@@ -1,14 +1,14 @@
 #![warn(clippy::missing_const_for_fn)]
-#![allow(unsupported_calling_conventions)]
 #![feature(const_extern_fn)]
 
+
 extern "C-unwind" fn c_unwind() {}
 //~^ ERROR: this could be a `const fn`
 extern "system" fn system() {}
 //~^ ERROR: this could be a `const fn`
 extern "system-unwind" fn system_unwind() {}
 //~^ ERROR: this could be a `const fn`
-pub extern "stdcall" fn std_call() {}
+pub extern "vectorcall" fn vector_call() {}
 //~^ ERROR: this could be a `const fn`
-pub extern "stdcall-unwind" fn std_call_unwind() {}
+pub extern "vectorcall-unwind" fn vector_call_unwind() {}
 //~^ ERROR: this could be a `const fn`
diff --git a/src/tools/clippy/tests/ui/missing_const_for_fn/could_be_const_with_const_extern_fn.stderr b/src/tools/clippy/tests/ui/missing_const_for_fn/could_be_const_with_const_extern_fn.stderr
@@ -36,23 +36,23 @@ LL | const extern "system-unwind" fn system_unwind() {}
 error: this could be a `const fn`
   --> tests/ui/missing_const_for_fn/could_be_const_with_const_extern_fn.rs:11:1
    |
-LL | pub extern "stdcall" fn std_call() {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL | pub extern "vectorcall" fn vector_call() {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
 help: make the function `const`
    |
-LL | pub const extern "stdcall" fn std_call() {}
+LL | pub const extern "vectorcall" fn vector_call() {}
    |     +++++
 
 error: this could be a `const fn`
   --> tests/ui/missing_const_for_fn/could_be_const_with_const_extern_fn.rs:13:1
    |
-LL | pub extern "stdcall-unwind" fn std_call_unwind() {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL | pub extern "vectorcall-unwind" fn vector_call_unwind() {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
 help: make the function `const`
    |
-LL | pub const extern "stdcall-unwind" fn std_call_unwind() {}
+LL | pub const extern "vectorcall-unwind" fn vector_call_unwind() {}
    |     +++++
 
 error: aborting due to 5 previous errors

diff --git a/tests/ui/abi/unsupported.aarch64.stderr b/tests/ui/abi/unsupported.aarch64.stderr
@@ -40,16 +40,12 @@ error[E0570]: `"thiscall"` is not a supported ABI for the current target
 LL | extern "thiscall" fn thiscall() {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-warning: use of calling convention not supported on this target
+error[E0570]: `"stdcall"` is not a supported ABI for the current target
   --> $DIR/unsupported.rs:56:1
    |
 LL | extern "stdcall" fn stdcall() {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = 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 #87678 <https://github.com/rust-lang/rust/issues/87678>
-   = note: `#[warn(unsupported_calling_conventions)]` on by default
 
-error: aborting due to 7 previous errors; 1 warning emitted
+error: aborting due to 8 previous errors
 
 For more information about this error, try `rustc --explain E0570`.
diff --git a/tests/ui/abi/unsupported.arm.stderr b/tests/ui/abi/unsupported.arm.stderr
@@ -34,16 +34,12 @@ error[E0570]: `"thiscall"` is not a supported ABI for the current target
 LL | extern "thiscall" fn thiscall() {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-warning: use of calling convention not supported on this target
+error[E0570]: `"stdcall"` is not a supported ABI for the current target
   --> $DIR/unsupported.rs:56:1
    |
 LL | extern "stdcall" fn stdcall() {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = 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 #87678 <https://github.com/rust-lang/rust/issues/87678>
-   = note: `#[warn(unsupported_calling_conventions)]` on by default
 
-error: aborting due to 6 previous errors; 1 warning emitted
+error: aborting due to 7 previous errors
 
 For more information about this error, try `rustc --explain E0570`.
diff --git a/tests/ui/abi/unsupported.riscv32.stderr b/tests/ui/abi/unsupported.riscv32.stderr
@@ -34,16 +34,12 @@ error[E0570]: `"thiscall"` is not a supported ABI for the current target
 LL | extern "thiscall" fn thiscall() {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-warning: use of calling convention not supported on this target
+error[E0570]: `"stdcall"` is not a supported ABI for the current target
   --> $DIR/unsupported.rs:56:1
    |
 LL | extern "stdcall" fn stdcall() {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = 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 #87678 <https://github.com/rust-lang/rust/issues/87678>
-   = note: `#[warn(unsupported_calling_conventions)]` on by default
 
-error: aborting due to 6 previous errors; 1 warning emitted
+error: aborting due to 7 previous errors
 
 For more information about this error, try `rustc --explain E0570`.
diff --git a/tests/ui/abi/unsupported.riscv64.stderr b/tests/ui/abi/unsupported.riscv64.stderr
@@ -34,16 +34,12 @@ error[E0570]: `"thiscall"` is not a supported ABI for the current target
 LL | extern "thiscall" fn thiscall() {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-warning: use of calling convention not supported on this target
+error[E0570]: `"stdcall"` is not a supported ABI for the current target
   --> $DIR/unsupported.rs:56:1
    |
 LL | extern "stdcall" fn stdcall() {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = 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 #87678 <https://github.com/rust-lang/rust/issues/87678>
-   = note: `#[warn(unsupported_calling_conventions)]` on by default
 
-error: aborting due to 6 previous errors; 1 warning emitted
+error: aborting due to 7 previous errors
 
 For more information about this error, try `rustc --explain E0570`.
diff --git a/tests/ui/abi/unsupported.rs b/tests/ui/abi/unsupported.rs
@@ -54,13 +54,8 @@ extern "thiscall" fn thiscall() {}
 //[riscv32]~^^^^ ERROR is not a supported ABI
 //[riscv64]~^^^^^ ERROR is not a supported ABI
 extern "stdcall" fn stdcall() {}
-//[x64]~^ WARN use of calling convention not supported
-//[x64]~^^ WARN this was previously accepted
-//[arm]~^^^ WARN use of calling convention not supported
-//[arm]~^^^^ WARN this was previously accepted
-//[aarch64]~^^^^^ WARN use of calling convention not supported
-//[aarch64]~^^^^^^ WARN this was previously accepted
-//[riscv32]~^^^^^^^ WARN use of calling convention not supported
-//[riscv32]~^^^^^^^^ WARN this was previously accepted
-//[riscv64]~^^^^^^^^^ WARN use of calling convention not supported
-//[riscv64]~^^^^^^^^^^ WARN this was previously accepted
+//[x64]~^ ERROR is not a supported ABI
+//[arm]~^^ ERROR is not a supported ABI
+//[aarch64]~^^^ ERROR is not a supported ABI
+//[riscv32]~^^^^ ERROR is not a supported ABI
+//[riscv64]~^^^^^ ERROR is not a supported ABI
diff --git a/tests/ui/abi/unsupported.x64.stderr b/tests/ui/abi/unsupported.x64.stderr
@@ -34,16 +34,12 @@ error[E0570]: `"thiscall"` is not a supported ABI for the current target
 LL | extern "thiscall" fn thiscall() {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-warning: use of calling convention not supported on this target
+error[E0570]: `"stdcall"` is not a supported ABI for the current target
   --> $DIR/unsupported.rs:56:1
    |
 LL | extern "stdcall" fn stdcall() {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = 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 #87678 <https://github.com/rust-lang/rust/issues/87678>
-   = note: `#[warn(unsupported_calling_conventions)]` on by default
 
-error: aborting due to 6 previous errors; 1 warning emitted
+error: aborting due to 7 previous errors
 
 For more information about this error, try `rustc --explain E0570`.