Add Span to StmtKind::Let.

Author: cjgillot

compiler/rustc_middle/src/mir/mod.rs

@@ -1984,6 +1984,13 @@ impl<'tcx> Rvalue<'tcx> {
 }
 
 impl BorrowKind {
+    pub fn mutability(&self) -> Mutability {
+        match *self {
+            BorrowKind::Shared | BorrowKind::Shallow | BorrowKind::Unique => Mutability::Not,
+            BorrowKind::Mut { .. } => Mutability::Mut,
+        }
+    }
+
     pub fn allows_two_phase_borrow(&self) -> bool {
         match *self {
             BorrowKind::Shared | BorrowKind::Shallow | BorrowKind::Unique => false,

compiler/rustc_middle/src/thir.rs

@@ -227,6 +227,9 @@ pub enum StmtKind<'tcx> {
 
         /// The lint level for this `let` statement.
         lint_level: LintLevel,
+
+        /// Span of the `let <PAT> = <INIT>` part.
+        span: Span,
     },
 }
 
@@ -594,6 +597,55 @@ impl<'tcx> Pat<'tcx> {
             _ => None,
         }
     }
+
+    /// Call `f` on every "binding" in a pattern, e.g., on `a` in
+    /// `match foo() { Some(a) => (), None => () }`
+    pub fn each_binding(&self, mut f: impl FnMut(Symbol, BindingMode, Ty<'tcx>, Span)) {
+        self.walk_always(|p| {
+            if let PatKind::Binding { name, mode, ty, .. } = p.kind {
+                f(name, mode, ty, p.span);
+            }
+        });
+    }
+
+    /// Walk the pattern in left-to-right order.
+    ///
+    /// If `it(pat)` returns `false`, the children are not visited.
+    pub fn walk(&self, mut it: impl FnMut(&Pat<'tcx>) -> bool) {
+        self.walk_(&mut it)
+    }
+
+    fn walk_(&self, it: &mut impl FnMut(&Pat<'tcx>) -> bool) {
+        if !it(self) {
+            return;
+        }
+
+        use PatKind::*;
+        match &self.kind {
+            Wild | Range(..) | Binding { subpattern: None, .. } | Constant { .. } => {}
+            AscribeUserType { subpattern, .. }
+            | Binding { subpattern: Some(subpattern), .. }
+            | Deref { subpattern } => subpattern.walk_(it),
+            Leaf { subpatterns } | Variant { subpatterns, .. } => {
+                subpatterns.iter().for_each(|field| field.pattern.walk_(it))
+            }
+            Or { pats } => pats.iter().for_each(|p| p.walk_(it)),
+            Array { box ref prefix, ref slice, box ref suffix }
+            | Slice { box ref prefix, ref slice, box ref suffix } => {
+                prefix.iter().chain(slice.iter()).chain(suffix.iter()).for_each(|p| p.walk_(it))
+            }
+        }
+    }
+
+    /// Walk the pattern in left-to-right order.
+    ///
+    /// If you always want to recurse, prefer this method over `walk`.
+    pub fn walk_always(&self, mut it: impl FnMut(&Pat<'tcx>)) {
+        self.walk(|p| {
+            it(p);
+            true
+        })
+    }
 }
 
 impl<'tcx> IntoDiagnosticArg for Pat<'tcx> {
@@ -879,7 +931,7 @@ mod size_asserts {
     static_assert_size!(ExprKind<'_>, 40);
     static_assert_size!(Pat<'_>, 72);
     static_assert_size!(PatKind<'_>, 56);
-    static_assert_size!(Stmt<'_>, 48);
-    static_assert_size!(StmtKind<'_>, 40);
+    static_assert_size!(Stmt<'_>, 56);
+    static_assert_size!(StmtKind<'_>, 48);
     // tidy-alphabetical-end
 }

compiler/rustc_middle/src/thir/visit.rs

@@ -175,6 +175,7 @@ pub fn walk_stmt<'a, 'tcx: 'a, V: Visitor<'a, 'tcx>>(visitor: &mut V, stmt: &Stm
             ref pattern,
             lint_level: _,
             else_block,
+            span: _,
         } => {
             if let Some(init) = initializer {
                 visitor.visit_expr(&visitor.thir()[*init]);

compiler/rustc_mir_build/src/build/block.rs

@@ -115,6 +115,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                     initializer: Some(initializer),
                     lint_level,
                     else_block: Some(else_block),
+                    span: _,
                 } => {
                     // When lowering the statement `let <pat> = <expr> else { <else> };`,
                     // the `<else>` block is nested in the parent scope enclosing this statement.
@@ -278,6 +279,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                     initializer,
                     lint_level,
                     else_block: None,
+                    span: _,
                 } => {
                     let ignores_expr_result = matches!(pattern.kind, PatKind::Wild);
                     this.block_context.push(BlockFrame::Statement { ignores_expr_result });

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

@@ -105,6 +105,10 @@ impl<'tcx> Cx<'tcx> {
                             }
                         }
 
+                        let span = match local.init {
+                            Some(init) => local.span.with_hi(init.span.hi()),
+                            None => local.span,
+                        };
                         let stmt = Stmt {
                             kind: StmtKind::Let {
                                 remainder_scope,
@@ -116,6 +120,7 @@ impl<'tcx> Cx<'tcx> {
                                 initializer: local.init.map(|init| self.mirror_expr(init)),
                                 else_block,
                                 lint_level: LintLevel::Explicit(local.hir_id),
+                                span,
                             },
                             opt_destruction_scope: opt_dxn_ext,
                         };

compiler/rustc_mir_build/src/thir/print.rs

@@ -151,6 +151,7 @@ impl<'a, 'tcx> ThirPrinter<'a, 'tcx> {
                 initializer,
                 else_block,
                 lint_level,
+                span,
             } => {
                 print_indented!(self, "kind: Let {", depth_lvl + 1);
                 print_indented!(
@@ -181,6 +182,7 @@ impl<'a, 'tcx> ThirPrinter<'a, 'tcx> {
                 }
 
                 print_indented!(self, format!("lint_level: {:?}", lint_level), depth_lvl + 2);
+                print_indented!(self, format!("span: {:?}", span), depth_lvl + 2);
                 print_indented!(self, "}", depth_lvl + 1);
             }
         }