Add loop head span to hir

Author: estebank

compiler/rustc_ast_lowering/src/expr.rs

@@ -10,9 +10,9 @@ use rustc_errors::struct_span_err;
 use rustc_hir as hir;
 use rustc_hir::def::Res;
 use rustc_session::parse::feature_err;
-use rustc_span::hygiene::ForLoopLoc;
 use rustc_span::source_map::{respan, DesugaringKind, Span, Spanned};
 use rustc_span::symbol::{sym, Ident, Symbol};
+use rustc_span::{hygiene::ForLoopLoc, DUMMY_SP};
 use rustc_target::asm;
 use std::collections::hash_map::Entry;
 use std::fmt::Write;
@@ -102,6 +102,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                         this.lower_block(body, false),
                         opt_label,
                         hir::LoopSource::Loop,
+                        DUMMY_SP,
                     )
                 }),
                 ExprKind::TryBlock(ref body) => self.lower_expr_try_block(body),
@@ -453,7 +454,12 @@ impl<'hir> LoweringContext<'_, 'hir> {
             self.expr_match(span, scrutinee, arena_vec![self; then_arm, else_arm], desugar);
 
         // `[opt_ident]: loop { ... }`
-        hir::ExprKind::Loop(self.block_expr(self.arena.alloc(match_expr)), opt_label, source)
+        hir::ExprKind::Loop(
+            self.block_expr(self.arena.alloc(match_expr)),
+            opt_label,
+            source,
+            span.with_hi(cond.span.hi()),
+        )
     }
 
     /// Desugar `try { <stmts>; <expr> }` into `{ <stmts>; ::std::ops::Try::from_ok(<expr>) }`,
@@ -748,7 +754,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         // loop { .. }
         let loop_expr = self.arena.alloc(hir::Expr {
             hir_id: loop_hir_id,
-            kind: hir::ExprKind::Loop(loop_block, None, hir::LoopSource::Loop),
+            kind: hir::ExprKind::Loop(loop_block, None, hir::LoopSource::Loop, span),
             span,
             attrs: ThinVec::new(),
         });
@@ -1709,7 +1715,12 @@ impl<'hir> LoweringContext<'_, 'hir> {
         );
 
         // `[opt_ident]: loop { ... }`
-        let kind = hir::ExprKind::Loop(loop_block, opt_label, hir::LoopSource::ForLoop);
+        let kind = hir::ExprKind::Loop(
+            loop_block,
+            opt_label,
+            hir::LoopSource::ForLoop,
+            e.span.with_hi(orig_head_span.hi()),
+        );
         let loop_expr = self.arena.alloc(hir::Expr {
             hir_id: self.lower_node_id(e.id),
             kind,

compiler/rustc_hir/src/hir.rs

@@ -1617,7 +1617,9 @@ pub enum ExprKind<'hir> {
     /// A conditionless loop (can be exited with `break`, `continue`, or `return`).
     ///
     /// I.e., `'label: loop { <block> }`.
-    Loop(&'hir Block<'hir>, Option<Label>, LoopSource),
+    ///
+    /// The `Span` is the loop header (`for x in y`/`while let pat = expr`).
+    Loop(&'hir Block<'hir>, Option<Label>, LoopSource, Span),
     /// A `match` block, with a source that indicates whether or not it is
     /// the result of a desugaring, and if so, which kind.
     Match(&'hir Expr<'hir>, &'hir [Arm<'hir>], MatchSource),

compiler/rustc_hir/src/intravisit.rs

@@ -1151,7 +1151,7 @@ pub fn walk_expr<'v, V: Visitor<'v>>(visitor: &mut V, expression: &'v Expr<'v>)
             visitor.visit_expr(then);
             walk_list!(visitor, visit_expr, else_opt);
         }
-        ExprKind::Loop(ref block, ref opt_label, _) => {
+        ExprKind::Loop(ref block, ref opt_label, _, _) => {
             walk_list!(visitor, visit_label, opt_label);
             visitor.visit_block(block);
         }

compiler/rustc_hir_pretty/src/lib.rs

@@ -1396,7 +1396,7 @@ impl<'a> State<'a> {
             hir::ExprKind::If(ref test, ref blk, ref elseopt) => {
                 self.print_if(&test, &blk, elseopt.as_ref().map(|e| &**e));
             }
-            hir::ExprKind::Loop(ref blk, opt_label, _) => {
+            hir::ExprKind::Loop(ref blk, opt_label, _, _) => {
                 if let Some(label) = opt_label {
                     self.print_ident(label.ident);
                     self.word_space(":");

compiler/rustc_mir_build/src/thir/cx/expr.rs

@@ -546,9 +546,7 @@ fn make_mirror_unadjusted<'a, 'tcx>(
             scrutinee: discr.to_ref(),
             arms: arms.iter().map(|a| convert_arm(cx, a)).collect(),
         },
-        hir::ExprKind::Loop(ref body, _, _) => {
-            ExprKind::Loop { body: block::to_expr_ref(cx, body) }
-        }
+        hir::ExprKind::Loop(ref body, ..) => ExprKind::Loop { body: block::to_expr_ref(cx, body) },
         hir::ExprKind::Field(ref source, ..) => ExprKind::Field {
             lhs: source.to_ref(),
             name: Field::new(cx.tcx.field_index(expr.hir_id, cx.typeck_results)),

compiler/rustc_passes/src/check_const.rs

@@ -199,7 +199,7 @@ impl<'tcx> Visitor<'tcx> for CheckConstVisitor<'tcx> {
             // Skip the following checks if we are not currently in a const context.
             _ if self.const_kind.is_none() => {}
 
-            hir::ExprKind::Loop(_, _, source) => {
+            hir::ExprKind::Loop(_, _, source, _) => {
                 self.const_check_violated(NonConstExpr::Loop(*source), e.span);
             }
 

compiler/rustc_passes/src/liveness.rs

@@ -844,7 +844,7 @@ impl<'a, 'tcx> Liveness<'a, 'tcx> {
 
             // Note that labels have been resolved, so we don't need to look
             // at the label ident
-            hir::ExprKind::Loop(ref blk, _, _) => self.propagate_through_loop(expr, &blk, succ),
+            hir::ExprKind::Loop(ref blk, ..) => self.propagate_through_loop(expr, &blk, succ),
 
             hir::ExprKind::If(ref cond, ref then, ref else_opt) => {
                 //

compiler/rustc_passes/src/loops.rs

@@ -53,7 +53,7 @@ impl<'a, 'hir> Visitor<'hir> for CheckLoopVisitor<'a, 'hir> {
 
     fn visit_expr(&mut self, e: &'hir hir::Expr<'hir>) {
         match e.kind {
-            hir::ExprKind::Loop(ref b, _, source) => {
+            hir::ExprKind::Loop(ref b, _, source, _) => {
                 self.with_context(Loop(source), |v| v.visit_block(&b));
             }
             hir::ExprKind::Closure(_, ref function_decl, b, span, movability) => {
@@ -89,8 +89,7 @@ impl<'a, 'hir> Visitor<'hir> for CheckLoopVisitor<'a, 'hir> {
                     Err(hir::LoopIdError::UnresolvedLabel) => None,
                 };
 
-                if let Some(loop_id) = loop_id {
-                    if let Node::Block(_) = self.hir_map.find(loop_id).unwrap() {
+                if let Some(Node::Block(_)) = loop_id.and_then(|id| self.hir_map.find(id)) {
                         return;
                     }
                 }

compiler/rustc_passes/src/region.rs

@@ -252,7 +252,7 @@ fn resolve_expr<'tcx>(visitor: &mut RegionResolutionVisitor<'tcx>, expr: &'tcx h
                 terminating(then.hir_id.local_id);
             }
 
-            hir::ExprKind::Loop(ref body, _, _) => {
+            hir::ExprKind::Loop(ref body, _, _, _) => {
                 terminating(body.hir_id.local_id);
             }
 

compiler/rustc_resolve/src/late/lifetimes.rs

@@ -1173,7 +1173,7 @@ fn extract_labels(ctxt: &mut LifetimeContext<'_, '_>, body: &hir::Body<'_>) {
     }
 
     fn expression_label(ex: &hir::Expr<'_>) -> Option<Ident> {
-        if let hir::ExprKind::Loop(_, Some(label), _) = ex.kind { Some(label.ident) } else { None }
+        if let hir::ExprKind::Loop(_, Some(label), ..) = ex.kind { Some(label.ident) } else { None }
     }
 
     fn check_if_label_shadows_lifetime(tcx: TyCtxt<'_>, mut scope: ScopeRef<'_>, label: Ident) {