Rollup merge of #86148 - FabianWolff:issue-85855, r=varkor

Check the number of generic lifetime and const parameters of intrinsics

This pull request fixes #85855. The current code for type checking intrinsics only checks the number of generic _type_ parameters, but does not check for an incorrect number of lifetime or const parameters, which can cause problems later on, such as the ICE in #85855, where the code thought that it was looking at a type parameter but found a lifetime parameter:
```
error: internal compiler error: compiler/rustc_middle/src/ty/generics.rs:188:18:
    expected type parameter, but found another generic parameter
```

The changes in this PR add checks for the number of lifetime and const parameters, expand the scope of `E0094` to also apply to these cases, and improve the error message by properly pluralizing the number of expected generic parameters.

5 files changed, 81 insertions, 30 deletions

diff --git a/compiler/rustc_error_codes/src/error_codes/E0094.md b/compiler/rustc_error_codes/src/error_codes/E0094.md
index 42baa65bf9f..ec86ec44ece 100644
--- a/compiler/rustc_error_codes/src/error_codes/E0094.md
+++ b/compiler/rustc_error_codes/src/error_codes/E0094.md
@@ -1,4 +1,4 @@
-An invalid number of type parameters was given to an intrinsic function.
+An invalid number of generic parameters was passed to an intrinsic function.
 
 Erroneous code example:
 
diff --git a/compiler/rustc_typeck/src/check/intrinsic.rs b/compiler/rustc_typeck/src/check/intrinsic.rs
index a259fc6a488..a56aefcef9c 100644
--- a/compiler/rustc_typeck/src/check/intrinsic.rs
+++ b/compiler/rustc_typeck/src/check/intrinsic.rs
@@ -3,11 +3,11 @@
 
 use crate::errors::{
     SimdShuffleMissingLength, UnrecognizedAtomicOperation, UnrecognizedIntrinsicFunction,
-    WrongNumberOfTypeArgumentsToInstrinsic,
+    WrongNumberOfGenericArgumentsToIntrinsic,
 };
 use crate::require_same_types;
 
-use rustc_errors::struct_span_err;
+use rustc_errors::{pluralize, struct_span_err};
 use rustc_hir as hir;
 use rustc_middle::traits::{ObligationCause, ObligationCauseCode};
 use rustc_middle::ty::subst::Subst;
@@ -21,36 +21,45 @@ fn equate_intrinsic_type<'tcx>(
     tcx: TyCtxt<'tcx>,
     it: &hir::ForeignItem<'_>,
     n_tps: usize,
+    n_lts: usize,
     sig: ty::PolyFnSig<'tcx>,
 ) {
-    match it.kind {
-        hir::ForeignItemKind::Fn(..) => {}
+    let (own_counts, span) = match &it.kind {
+        hir::ForeignItemKind::Fn(.., generics) => {
+            let own_counts = tcx.generics_of(it.def_id.to_def_id()).own_counts();
+            (own_counts, generics.span)
+        }
         _ => {
             struct_span_err!(tcx.sess, it.span, E0622, "intrinsic must be a function")
                 .span_label(it.span, "expected a function")
                 .emit();
             return;
         }
-    }
+    };
 
-    let i_n_tps = tcx.generics_of(it.def_id).own_counts().types;
-    if i_n_tps != n_tps {
-        let span = match it.kind {
-            hir::ForeignItemKind::Fn(_, _, ref generics) => generics.span,
-            _ => bug!(),
-        };
+    let gen_count_ok = |found: usize, expected: usize, descr: &str| -> bool {
+        if found != expected {
+            tcx.sess.emit_err(WrongNumberOfGenericArgumentsToIntrinsic {
+                span,
+                found,
+                expected,
+                expected_pluralize: pluralize!(expected),
+                descr,
+            });
+            false
+        } else {
+            true
+        }
+    };
 
-        tcx.sess.emit_err(WrongNumberOfTypeArgumentsToInstrinsic {
-            span,
-            found: i_n_tps,
-            expected: n_tps,
-        });
-        return;
+    if gen_count_ok(own_counts.lifetimes, n_lts, "lifetime")
+        && gen_count_ok(own_counts.types, n_tps, "type")
+        && gen_count_ok(own_counts.consts, 0, "const")
+    {
+        let fty = tcx.mk_fn_ptr(sig);
+        let cause = ObligationCause::new(it.span, it.hir_id(), ObligationCauseCode::IntrinsicType);
+        require_same_types(tcx, &cause, tcx.mk_fn_ptr(tcx.fn_sig(it.def_id)), fty);
     }
-
-    let fty = tcx.mk_fn_ptr(sig);
-    let cause = ObligationCause::new(it.span, it.hir_id(), ObligationCauseCode::IntrinsicType);
-    require_same_types(tcx, &cause, tcx.mk_fn_ptr(tcx.fn_sig(it.def_id)), fty);
 }
 
 /// Returns the unsafety of the given intrinsic.
@@ -121,7 +130,7 @@ pub fn check_intrinsic_type(tcx: TyCtxt<'_>, it: &hir::ForeignItem<'_>) {
         })
     };
 
-    let (n_tps, inputs, output, unsafety) = if name_str.starts_with("atomic_") {
+    let (n_tps, n_lts, inputs, output, unsafety) = if name_str.starts_with("atomic_") {
         let split: Vec<&str> = name_str.split('_').collect();
         assert!(split.len() >= 2, "Atomic intrinsic in an incorrect format");
 
@@ -143,7 +152,7 @@ pub fn check_intrinsic_type(tcx: TyCtxt<'_>, it: &hir::ForeignItem<'_>) {
                 return;
             }
         };
-        (n_tps, inputs, output, hir::Unsafety::Unsafe)
+        (n_tps, 0, inputs, output, hir::Unsafety::Unsafe)
     } else {
         let unsafety = intrinsic_operation_unsafety(intrinsic_name);
         let (n_tps, inputs, output) = match intrinsic_name {
@@ -372,11 +381,11 @@ pub fn check_intrinsic_type(tcx: TyCtxt<'_>, it: &hir::ForeignItem<'_>) {
                 return;
             }
         };
-        (n_tps, inputs, output, unsafety)
+        (n_tps, 0, inputs, output, unsafety)
     };
     let sig = tcx.mk_fn_sig(inputs.into_iter(), output, false, unsafety, Abi::RustIntrinsic);
     let sig = ty::Binder::bind_with_vars(sig, bound_vars);
-    equate_intrinsic_type(tcx, it, n_tps, sig)
+    equate_intrinsic_type(tcx, it, n_tps, n_lts, sig)
 }
 
 /// Type-check `extern "platform-intrinsic" { ... }` functions.
@@ -472,5 +481,5 @@ pub fn check_platform_intrinsic_type(tcx: TyCtxt<'_>, it: &hir::ForeignItem<'_>)
         Abi::PlatformIntrinsic,
     );
     let sig = ty::Binder::dummy(sig);
-    equate_intrinsic_type(tcx, it, n_tps, sig)
+    equate_intrinsic_type(tcx, it, n_tps, 0, sig)
 }
diff --git a/compiler/rustc_typeck/src/errors.rs b/compiler/rustc_typeck/src/errors.rs
index 1a21c085d53..1e6a240b2f8 100644
--- a/compiler/rustc_typeck/src/errors.rs
+++ b/compiler/rustc_typeck/src/errors.rs
@@ -24,13 +24,15 @@ pub struct UnrecognizedAtomicOperation<'a> {
 
 #[derive(SessionDiagnostic)]
 #[error = "E0094"]
-pub struct WrongNumberOfTypeArgumentsToInstrinsic {
-    #[message = "intrinsic has wrong number of type \
+pub struct WrongNumberOfGenericArgumentsToIntrinsic<'a> {
+    #[message = "intrinsic has wrong number of {descr} \
                          parameters: found {found}, expected {expected}"]
-    #[label = "expected {expected} type parameter"]
+    #[label = "expected {expected} {descr} parameter{expected_pluralize}"]
     pub span: Span,
     pub found: usize,
     pub expected: usize,
+    pub expected_pluralize: &'a str,
+    pub descr: &'a str,
 }
 
 #[derive(SessionDiagnostic)]
diff --git a/src/test/ui/simd-intrinsic/issue-85855.rs b/src/test/ui/simd-intrinsic/issue-85855.rs
new file mode 100644
index 00000000000..f276fbd6694
--- /dev/null
+++ b/src/test/ui/simd-intrinsic/issue-85855.rs
@@ -0,0 +1,19 @@
+// Check that appropriate errors are reported if an intrinsic is defined
+// with the wrong number of generic lifetime/type/const parameters, and
+// that no ICE occurs in these cases.
+
+#![feature(platform_intrinsics)]
+#![crate_type="lib"]
+
+extern "platform-intrinsic" {
+    fn simd_saturating_add<'a, T: 'a>(x: T, y: T);
+    //~^ ERROR: intrinsic has wrong number of lifetime parameters
+
+    fn simd_add<'a, T>(x: T, y: T) -> T;
+
+    fn simd_sub<T, U>(x: T, y: U);
+    //~^ ERROR: intrinsic has wrong number of type parameters
+
+    fn simd_mul<T, const N: usize>(x: T, y: T);
+    //~^ ERROR: intrinsic has wrong number of const parameters
+}
diff --git a/src/test/ui/simd-intrinsic/issue-85855.stderr b/src/test/ui/simd-intrinsic/issue-85855.stderr
new file mode 100644
index 00000000000..fb2f1fbc5b1
--- /dev/null
+++ b/src/test/ui/simd-intrinsic/issue-85855.stderr
@@ -0,0 +1,21 @@
+error[E0094]: intrinsic has wrong number of lifetime parameters: found 1, expected 0
+  --> $DIR/issue-85855.rs:9:27
+   |
+LL |     fn simd_saturating_add<'a, T: 'a>(x: T, y: T);
+   |                           ^^^^^^^^^^^ expected 0 lifetime parameters
+
+error[E0094]: intrinsic has wrong number of type parameters: found 2, expected 1
+  --> $DIR/issue-85855.rs:14:16
+   |
+LL |     fn simd_sub<T, U>(x: T, y: U);
+   |                ^^^^^^ expected 1 type parameter
+
+error[E0094]: intrinsic has wrong number of const parameters: found 1, expected 0
+  --> $DIR/issue-85855.rs:17:16
+   |
+LL |     fn simd_mul<T, const N: usize>(x: T, y: T);
+   |                ^^^^^^^^^^^^^^^^^^^ expected 0 const parameters
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0094`.