Rollup merge of rust-lang#110823 - compiler-errors:tweak-await-span, r=b-naber

Tweak await span to not contain dot

Fixes a discrepancy between method calls and await expressions where the latter are desugared to have a span that *contains* the dot (i.e. `.await`) but method call identifiers don't contain the dot. This leads to weird suggestions suggestions in borrowck -- see linked issue.

Fixes rust-lang#110761

This mostly touches a bunch of tests to tighten their `await` span.

Author: matthiaskrgr

compiler/rustc_ast/src/ast.rs

@@ -1430,8 +1430,8 @@ pub enum ExprKind {
     /// The async block used to have a `NodeId`, which was removed in favor of
     /// using the parent `NodeId` of the parent `Expr`.
     Async(CaptureBy, P<Block>),
-    /// An await expression (`my_future.await`).
-    Await(P<Expr>),
+    /// An await expression (`my_future.await`). Span is of await keyword.
+    Await(P<Expr>, Span),
 
     /// A try block (`try { ... }`).
     TryBlock(P<Block>),

compiler/rustc_ast/src/mut_visit.rs

@@ -1415,7 +1415,10 @@ pub fn noop_visit_expr<T: MutVisitor>(
         ExprKind::Async(_capture_by, body) => {
             vis.visit_block(body);
         }
-        ExprKind::Await(expr) => vis.visit_expr(expr),
+        ExprKind::Await(expr, await_kw_span) => {
+            vis.visit_expr(expr);
+            vis.visit_span(await_kw_span);
+        }
         ExprKind::Assign(el, er, _) => {
             vis.visit_expr(el);
             vis.visit_expr(er);

compiler/rustc_ast/src/util/parser.rs

@@ -388,7 +388,7 @@ pub fn contains_exterior_struct_lit(value: &ast::Expr) -> bool {
             // X { y: 1 } + X { y: 2 }
             contains_exterior_struct_lit(lhs) || contains_exterior_struct_lit(rhs)
         }
-        ast::ExprKind::Await(x)
+        ast::ExprKind::Await(x, _)
         | ast::ExprKind::Unary(_, x)
         | ast::ExprKind::Cast(x, _)
         | ast::ExprKind::Type(x, _)

compiler/rustc_ast/src/visit.rs

@@ -864,7 +864,7 @@ pub fn walk_expr<'a, V: Visitor<'a>>(visitor: &mut V, expression: &'a Expr) {
         ExprKind::Async(_, body) => {
             visitor.visit_block(body);
         }
-        ExprKind::Await(expr) => visitor.visit_expr(expr),
+        ExprKind::Await(expr, _) => visitor.visit_expr(expr),
         ExprKind::Assign(lhs, rhs, _) => {
             visitor.visit_expr(lhs);
             visitor.visit_expr(rhs);

compiler/rustc_ast_lowering/src/errors.rs

@@ -108,7 +108,7 @@ pub struct BaseExpressionDoubleDot {
 pub struct AwaitOnlyInAsyncFnAndBlocks {
     #[primary_span]
     #[label]
-    pub dot_await_span: Span,
+    pub await_kw_span: Span,
     #[label(ast_lowering_this_not_async)]
     pub item_span: Option<Span>,
 }

compiler/rustc_ast_lowering/src/expr.rs

@@ -185,21 +185,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     hir::AsyncGeneratorKind::Block,
                     |this| this.with_new_scopes(|this| this.lower_block_expr(block)),
                 ),
-                ExprKind::Await(expr) => {
-                    let dot_await_span = if expr.span.hi() < e.span.hi() {
-                        let span_with_whitespace = self
-                            .tcx
-                            .sess
-                            .source_map()
-                            .span_extend_while(expr.span, char::is_whitespace)
-                            .unwrap_or(expr.span);
-                        span_with_whitespace.shrink_to_hi().with_hi(e.span.hi())
-                    } else {
-                        // this is a recovered `await expr`
-                        e.span
-                    };
-                    self.lower_expr_await(dot_await_span, expr)
-                }
+                ExprKind::Await(expr, await_kw_span) => self.lower_expr_await(*await_kw_span, expr),
                 ExprKind::Closure(box Closure {
                     binder,
                     capture_clause,
@@ -710,18 +696,18 @@ impl<'hir> LoweringContext<'_, 'hir> {
     ///     }
     /// }
     /// ```
-    fn lower_expr_await(&mut self, dot_await_span: Span, expr: &Expr) -> hir::ExprKind<'hir> {
-        let full_span = expr.span.to(dot_await_span);
+    fn lower_expr_await(&mut self, await_kw_span: Span, expr: &Expr) -> hir::ExprKind<'hir> {
+        let full_span = expr.span.to(await_kw_span);
         match self.generator_kind {
             Some(hir::GeneratorKind::Async(_)) => {}
             Some(hir::GeneratorKind::Gen) | None => {
                 self.tcx.sess.emit_err(AwaitOnlyInAsyncFnAndBlocks {
-                    dot_await_span,
+                    await_kw_span,
                     item_span: self.current_item,
                 });
             }
         }
-        let span = self.mark_span_with_reason(DesugaringKind::Await, dot_await_span, None);
+        let span = self.mark_span_with_reason(DesugaringKind::Await, await_kw_span, None);
         let gen_future_span = self.mark_span_with_reason(
             DesugaringKind::Await,
             full_span,

compiler/rustc_ast_lowering/src/format.rs

@@ -583,7 +583,7 @@ fn may_contain_yield_point(e: &ast::Expr) -> bool {
 
     impl Visitor<'_> for MayContainYieldPoint {
         fn visit_expr(&mut self, e: &ast::Expr) {
-            if let ast::ExprKind::Await(_) | ast::ExprKind::Yield(_) = e.kind {
+            if let ast::ExprKind::Await(_, _) | ast::ExprKind::Yield(_) = e.kind {
                 self.0 = true;
             } else {
                 visit::walk_expr(self, e);

compiler/rustc_ast_pretty/src/pprust/state/expr.rs

@@ -447,7 +447,7 @@ impl<'a> State<'a> {
                 self.ibox(0);
                 self.print_block_with_attrs(blk, attrs);
             }
-            ast::ExprKind::Await(expr) => {
+            ast::ExprKind::Await(expr, _) => {
                 self.print_expr_maybe_paren(expr, parser::PREC_POSTFIX);
                 self.word(".await");
             }

compiler/rustc_borrowck/messages.ftl

@@ -203,6 +203,15 @@ borrowck_moved_due_to_method_call =
         *[false] call
     }
 
+borrowck_moved_due_to_await =
+    {$place_name} {$is_partial ->
+        [true] partially moved
+        *[false] moved
+    } due to this {$is_loop_message ->
+        [true] await, in previous iteration of loop
+        *[false] await
+    }
+
 borrowck_value_moved_here =
     value {$is_partial ->
         [true] partially moved

compiler/rustc_borrowck/src/diagnostics/mod.rs

@@ -1085,12 +1085,21 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                             }
                         }
                     } else {
-                        err.subdiagnostic(CaptureReasonLabel::MethodCall {
-                            fn_call_span,
-                            place_name: &place_name,
-                            is_partial,
-                            is_loop_message,
-                        });
+                        if let Some((CallDesugaringKind::Await, _)) = desugaring {
+                            err.subdiagnostic(CaptureReasonLabel::Await {
+                                fn_call_span,
+                                place_name: &place_name,
+                                is_partial,
+                                is_loop_message,
+                            });
+                        } else {
+                            err.subdiagnostic(CaptureReasonLabel::MethodCall {
+                                fn_call_span,
+                                place_name: &place_name,
+                                is_partial,
+                                is_loop_message,
+                            });
+                        }
                         // Erase and shadow everything that could be passed to the new infcx.
                         let ty = moved_place.ty(self.body, tcx).ty;