Rollup of 8 pull requests

compiler/rustc_codegen_ssa/src/mir/debuginfo.rs

@@ -320,6 +320,8 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
     ) -> Option<IndexVec<mir::Local, Vec<PerLocalVarDebugInfo<'tcx, Bx::DIVariable>>>> {
         let full_debug_info = self.cx.sess().opts.debuginfo == DebugInfo::Full;
 
+        let target_is_msvc = self.cx.sess().target.is_like_msvc;
+
         if !full_debug_info && self.cx.sess().fewer_names() {
             return None;
         }
@@ -341,11 +343,29 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                             && var.source_info.scope == mir::OUTERMOST_SOURCE_SCOPE
                         {
                             let arg_index = place.local.index() - 1;
-
-                            // FIXME(eddyb) shouldn't `ArgumentVariable` indices be
-                            // offset in closures to account for the hidden environment?
-                            // Also, is this `+ 1` needed at all?
-                            VariableKind::ArgumentVariable(arg_index + 1)
+                            if target_is_msvc {
+                                // Rust compiler decomposes every &str or slice argument into two components:
+                                // a pointer to the memory address where the data is stored and a usize representing
+                                // the length of the str (or slice). These components will later be used to reconstruct
+                                // the original argument inside the body of the function that owns it (see the
+                                // definition of debug_introduce_local for more details).
+                                //
+                                // Since the original argument is declared inside a function rather than being passed
+                                // in as an argument, it must be marked as a LocalVariable for MSVC debuggers to visualize
+                                // its data correctly. (See issue #81894 for an in-depth description of the problem).
+                                match *var_ty.kind() {
+                                    ty::Ref(_, inner_type, _) => match *inner_type.kind() {
+                                        ty::Slice(_) | ty::Str => VariableKind::LocalVariable,
+                                        _ => VariableKind::ArgumentVariable(arg_index + 1),
+                                    },
+                                    _ => VariableKind::ArgumentVariable(arg_index + 1),
+                                }
+                            } else {
+                                // FIXME(eddyb) shouldn't `ArgumentVariable` indices be
+                                // offset in closures to account for the hidden environment?
+                                // Also, is this `+ 1` needed at all?
+                                VariableKind::ArgumentVariable(arg_index + 1)
+                            }
                         } else {
                             VariableKind::LocalVariable
                         };

compiler/rustc_expand/src/expand.rs

@@ -22,7 +22,7 @@ use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_data_structures::sync::Lrc;
 use rustc_errors::{Applicability, PResult};
 use rustc_feature::Features;
-use rustc_parse::parser::{AttemptLocalParseRecovery, ForceCollect, Parser};
+use rustc_parse::parser::{AttemptLocalParseRecovery, ForceCollect, GateOr, Parser, RecoverComma};
 use rustc_parse::validate_attr;
 use rustc_session::lint::builtin::UNUSED_DOC_COMMENTS;
 use rustc_session::lint::BuiltinLintDiagnostics;
@@ -914,7 +914,9 @@ pub fn parse_ast_fragment<'a>(
             }
         }
         AstFragmentKind::Ty => AstFragment::Ty(this.parse_ty()?),
-        AstFragmentKind::Pat => AstFragment::Pat(this.parse_pat(None)?),
+        AstFragmentKind::Pat => {
+            AstFragment::Pat(this.parse_pat_allow_top_alt(None, GateOr::Yes, RecoverComma::No)?)
+        }
         AstFragmentKind::Arms
         | AstFragmentKind::Fields
         | AstFragmentKind::FieldPats

compiler/rustc_infer/src/infer/error_reporting/nice_region_error/mod.rs

@@ -43,7 +43,7 @@ impl<'cx, 'tcx> NiceRegionError<'cx, 'tcx> {
         self.infcx.tcx
     }
 
-    pub fn try_report_from_nll(&self) -> Option<DiagnosticBuilder<'cx>> {
+    pub fn try_report_from_nll(&self) -> Option<DiagnosticBuilder<'tcx>> {
         // Due to the improved diagnostics returned by the MIR borrow checker, only a subset of
         // the nice region errors are required when running under the MIR borrow checker.
         self.try_report_named_anon_conflict().or_else(|| self.try_report_placeholder_conflict())

compiler/rustc_infer/src/infer/error_reporting/nice_region_error/named_anon_conflict.rs

@@ -9,7 +9,7 @@ use rustc_middle::ty;
 impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
     /// When given a `ConcreteFailure` for a function with parameters containing a named region and
     /// an anonymous region, emit an descriptive diagnostic error.
-    pub(super) fn try_report_named_anon_conflict(&self) -> Option<DiagnosticBuilder<'a>> {
+    pub(super) fn try_report_named_anon_conflict(&self) -> Option<DiagnosticBuilder<'tcx>> {
         let (span, sub, sup) = self.regions()?;
 
         debug!(