6 files changed, 59 insertions, 9 deletions
diff --git a/compiler/rustc_codegen_llvm/src/asm.rs b/compiler/rustc_codegen_llvm/src/asm.rs
index e723187ff1f..017513721b7 100644
--- a/compiler/rustc_codegen_llvm/src/asm.rs
+++ b/compiler/rustc_codegen_llvm/src/asm.rs
@@ -551,6 +551,8 @@ fn reg_to_llvm(reg: InlineAsmRegOrRegClass, layout: Option<&TyAndLayout<'_>>) ->
                 format!("{{{}}}", reg.name())
             }
         }
+        // The constraints can be retrieved from
+        // https://llvm.org/docs/LangRef.html#supported-constraint-code-list
         InlineAsmRegOrRegClass::RegClass(reg) => match reg {
             InlineAsmRegClass::AArch64(AArch64InlineAsmRegClass::reg) => "r",
             InlineAsmRegClass::AArch64(AArch64InlineAsmRegClass::vreg) => "w",
@@ -624,6 +626,8 @@ fn modifier_to_llvm(
     reg: InlineAsmRegClass,
     modifier: Option<char>,
 ) -> Option<char> {
+    // The modifiers can be retrieved from
+    // https://llvm.org/docs/LangRef.html#asm-template-argument-modifiers
     match reg {
         InlineAsmRegClass::AArch64(AArch64InlineAsmRegClass::reg) => modifier,
         InlineAsmRegClass::AArch64(AArch64InlineAsmRegClass::vreg)
diff --git a/compiler/rustc_error_messages/locales/en-US/metadata.ftl b/compiler/rustc_error_messages/locales/en-US/metadata.ftl
index d27100c56af..08e553d9f15 100644
--- a/compiler/rustc_error_messages/locales/en-US/metadata.ftl
+++ b/compiler/rustc_error_messages/locales/en-US/metadata.ftl
@@ -165,6 +165,8 @@ metadata_failed_write_error =
 metadata_missing_native_library =
     could not find native static library `{$libname}`, perhaps an -L flag is missing?
 
+metadata_only_provide_library_name = only provide the library name `{$suggested_name}`, not the full filename
+
 metadata_failed_create_tempdir =
     couldn't create a temp dir: {$err}
 
diff --git a/compiler/rustc_hir_analysis/src/check/check.rs b/compiler/rustc_hir_analysis/src/check/check.rs
index 7cee9779c5f..c3583eeb430 100644
--- a/compiler/rustc_hir_analysis/src/check/check.rs
+++ b/compiler/rustc_hir_analysis/src/check/check.rs
@@ -732,8 +732,6 @@ fn check_opaque_meets_bounds<'tcx>(
     span: Span,
     origin: &hir::OpaqueTyOrigin,
 ) {
-    let hidden_type = tcx.bound_type_of(def_id.to_def_id()).subst(tcx, substs);
-
     let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
     let defining_use_anchor = match *origin {
         hir::OpaqueTyOrigin::FnReturn(did) | hir::OpaqueTyOrigin::AsyncFn(did) => did,
@@ -748,14 +746,26 @@ fn check_opaque_meets_bounds<'tcx>(
     let ocx = ObligationCtxt::new(&infcx);
     let opaque_ty = tcx.mk_opaque(def_id.to_def_id(), substs);
 
+    // `ReErased` regions appear in the "parent_substs" of closures/generators.
+    // We're ignoring them here and replacing them with fresh region variables.
+    // See tests in ui/type-alias-impl-trait/closure_{parent_substs,wf_outlives}.rs.
+    //
+    // FIXME: Consider wrapping the hidden type in an existential `Binder` and instantiating it
+    // here rather than using ReErased.
+    let hidden_ty = tcx.bound_type_of(def_id.to_def_id()).subst(tcx, substs);
+    let hidden_ty = tcx.fold_regions(hidden_ty, |re, _dbi| match re.kind() {
+        ty::ReErased => infcx.next_region_var(RegionVariableOrigin::MiscVariable(span)),
+        _ => re,
+    });
+
     let misc_cause = traits::ObligationCause::misc(span, hir_id);
 
-    match infcx.at(&misc_cause, param_env).eq(opaque_ty, hidden_type) {
+    match infcx.at(&misc_cause, param_env).eq(opaque_ty, hidden_ty) {
         Ok(infer_ok) => ocx.register_infer_ok_obligations(infer_ok),
         Err(ty_err) => {
             tcx.sess.delay_span_bug(
                 span,
-                &format!("could not unify `{hidden_type}` with revealed type:\n{ty_err}"),
+                &format!("could not unify `{hidden_ty}` with revealed type:\n{ty_err}"),
             );
         }
     }
@@ -764,7 +774,7 @@ fn check_opaque_meets_bounds<'tcx>(
     // Defining use functions may have more bounds than the opaque type, which is ok, as long as the
     // hidden type is well formed even without those bounds.
     let predicate =
-        ty::Binder::dummy(ty::PredicateKind::WellFormed(hidden_type.into())).to_predicate(tcx);
+        ty::Binder::dummy(ty::PredicateKind::WellFormed(hidden_ty.into())).to_predicate(tcx);
     ocx.register_obligation(Obligation::new(misc_cause, param_env, predicate));
 
     // Check that all obligations are satisfied by the implementation's
diff --git a/compiler/rustc_metadata/src/errors.rs b/compiler/rustc_metadata/src/errors.rs
index 1cd550644bf..dbfa22aaff0 100644
--- a/compiler/rustc_metadata/src/errors.rs
+++ b/compiler/rustc_metadata/src/errors.rs
@@ -372,7 +372,41 @@ pub struct FailedWriteError {
 #[derive(Diagnostic)]
 #[diag(metadata::missing_native_library)]
 pub struct MissingNativeLibrary<'a> {
-    pub libname: &'a str,
+    libname: &'a str,
+    #[subdiagnostic]
+    suggest_name: Option<SuggestLibraryName<'a>>,
+}
+
+impl<'a> MissingNativeLibrary<'a> {
+    pub fn new(libname: &'a str, verbatim: bool) -> Self {
+        // if it looks like the user has provided a complete filename rather just the bare lib name,
+        // then provide a note that they might want to try trimming the name
+        let suggested_name = if !verbatim {
+            if let Some(libname) = libname.strip_prefix("lib") && let Some(libname) = libname.strip_suffix(".a") {
+                // this is a unix style filename so trim prefix & suffix
+                Some(libname)
+            } else if let Some(libname) = libname.strip_suffix(".lib") {
+                // this is a Windows style filename so just trim the suffix
+                Some(libname)
+            } else {
+                None
+            }
+        } else {
+            None
+        };
+
+        Self {
+            libname,
+            suggest_name: suggested_name
+                .map(|suggested_name| SuggestLibraryName { suggested_name }),
+        }
+    }
+}
+
+#[derive(Subdiagnostic)]
+#[help(metadata::only_provide_library_name)]
+pub struct SuggestLibraryName<'a> {
+    suggested_name: &'a str,
 }
 
 #[derive(Diagnostic)]
diff --git a/compiler/rustc_metadata/src/native_libs.rs b/compiler/rustc_metadata/src/native_libs.rs
index 9abb5c74895..676c67bad82 100644
--- a/compiler/rustc_metadata/src/native_libs.rs
+++ b/compiler/rustc_metadata/src/native_libs.rs
@@ -52,7 +52,7 @@ pub fn find_native_static_library(
         }
     }
 
-    sess.emit_fatal(MissingNativeLibrary { libname: name });
+    sess.emit_fatal(MissingNativeLibrary::new(name, verbatim.unwrap_or(false)));
 }
 
 fn find_bundled_library(
diff --git a/compiler/rustc_mir_build/src/build/expr/as_rvalue.rs b/compiler/rustc_mir_build/src/build/expr/as_rvalue.rs
index 35a00da8d38..3dafdcb7887 100644
--- a/compiler/rustc_mir_build/src/build/expr/as_rvalue.rs
+++ b/compiler/rustc_mir_build/src/build/expr/as_rvalue.rs
@@ -197,13 +197,13 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 // create all the steps directly in MIR with operations all backends need to support anyway.
                 let (source, ty) = if let ty::Adt(adt_def, ..) = source.ty.kind() && adt_def.is_enum() {
                     let discr_ty = adt_def.repr().discr_type().to_ty(this.tcx);
-                    let place = unpack!(block = this.as_place(block, source));
+                    let temp = unpack!(block = this.as_temp(block, scope, source, Mutability::Not));
                     let discr = this.temp(discr_ty, source.span);
                     this.cfg.push_assign(
                         block,
                         source_info,
                         discr,
-                        Rvalue::Discriminant(place),
+                        Rvalue::Discriminant(temp.into()),
                     );
 
                     (Operand::Move(discr), discr_ty)