Auto merge of #120619 - compiler-errors:param, r=lcnr

Assert that params with the same *index* have the same *name*

Found this bug when trying to build libcore with the new solver, since it will canonicalize two params with the same index into *different* placeholders if those params differ by name.

1 files changed, 21 insertions, 4 deletions

diff --git a/compiler/rustc_hir_analysis/src/check/intrinsic.rs b/compiler/rustc_hir_analysis/src/check/intrinsic.rs
index 96b0cffc8a3..dc391ab5648 100644
--- a/compiler/rustc_hir_analysis/src/check/intrinsic.rs
+++ b/compiler/rustc_hir_analysis/src/check/intrinsic.rs
@@ -12,7 +12,7 @@ use rustc_errors::{codes::*, struct_span_code_err, DiagnosticMessage};
 use rustc_hir as hir;
 use rustc_middle::traits::{ObligationCause, ObligationCauseCode};
 use rustc_middle::ty::{self, Ty, TyCtxt};
-use rustc_span::symbol::{kw, sym, Symbol};
+use rustc_span::symbol::{kw, sym};
 use rustc_target::spec::abi::Abi;
 
 fn equate_intrinsic_type<'tcx>(
@@ -133,7 +133,17 @@ pub fn intrinsic_operation_unsafety(tcx: TyCtxt<'_>, intrinsic_id: DefId) -> hir
 /// Remember to add all intrinsics here, in `compiler/rustc_codegen_llvm/src/intrinsic.rs`,
 /// and in `library/core/src/intrinsics.rs`.
 pub fn check_intrinsic_type(tcx: TyCtxt<'_>, it: &hir::ForeignItem<'_>) {
-    let param = |n| Ty::new_param(tcx, n, Symbol::intern(&format!("P{n}")));
+    let generics = tcx.generics_of(it.owner_id);
+    let param = |n| {
+        if let Some(&ty::GenericParamDef {
+            name, kind: ty::GenericParamDefKind::Type { .. }, ..
+        }) = generics.opt_param_at(n as usize, tcx)
+        {
+            Ty::new_param(tcx, n, name)
+        } else {
+            Ty::new_error_with_message(tcx, tcx.def_span(it.owner_id), "expected param")
+        }
+    };
     let intrinsic_id = it.owner_id.to_def_id();
     let intrinsic_name = tcx.item_name(intrinsic_id);
     let name_str = intrinsic_name.as_str();
@@ -478,9 +488,16 @@ pub fn check_intrinsic_type(tcx: TyCtxt<'_>, it: &hir::ForeignItem<'_>) {
 
 /// Type-check `extern "platform-intrinsic" { ... }` functions.
 pub fn check_platform_intrinsic_type(tcx: TyCtxt<'_>, it: &hir::ForeignItem<'_>) {
+    let generics = tcx.generics_of(it.owner_id);
     let param = |n| {
-        let name = Symbol::intern(&format!("P{n}"));
-        Ty::new_param(tcx, n, name)
+        if let Some(&ty::GenericParamDef {
+            name, kind: ty::GenericParamDefKind::Type { .. }, ..
+        }) = generics.opt_param_at(n as usize, tcx)
+        {
+            Ty::new_param(tcx, n, name)
+        } else {
+            Ty::new_error_with_message(tcx, tcx.def_span(it.owner_id), "expected param")
+        }
     };
 
     let name = it.ident.name;