From 237576c51ca39eaf0c98814b223d2464b2271d9e Mon Sep 17 00:00:00 2001
From: Sarthak Singh <sarthak.singh99@gmail.com>
Date: Tue, 27 Feb 2024 21:10:00 +0530
Subject: [PATCH] Continue inside a labeled block now lowers to a error when to
 lowering the ast

---
 compiler/rustc_ast_lowering/messages.ftl      |  5 +++
 compiler/rustc_ast_lowering/src/errors.rs     | 10 +++++
 compiler/rustc_ast_lowering/src/expr.rs       | 26 +++++++++--
 compiler/rustc_ast_lowering/src/lib.rs        |  2 +-
 compiler/rustc_middle/src/ty/mod.rs           |  3 +-
 compiler/rustc_resolve/src/late.rs            | 44 +++++++++++++------
 .../rustc_resolve/src/late/diagnostics.rs     |  2 +-
 compiler/rustc_resolve/src/lib.rs             |  3 +-
 .../cont-in-block/cont-in-fn-issue-113379.rs  | 28 ++++++++++++
 .../cont-in-fn-issue-113379.stderr            | 31 +++++++++++++
 .../cont-in-match-arm-issue-121623.rs         |  8 ++++
 .../cont-in-match-arm-issue-121623.stderr     | 14 ++++++
 12 files changed, 156 insertions(+), 20 deletions(-)
 create mode 100644 tests/ui/lowering/cont-in-block/cont-in-fn-issue-113379.rs
 create mode 100644 tests/ui/lowering/cont-in-block/cont-in-fn-issue-113379.stderr
 create mode 100644 tests/ui/lowering/cont-in-block/cont-in-match-arm-issue-121623.rs
 create mode 100644 tests/ui/lowering/cont-in-block/cont-in-match-arm-issue-121623.stderr

diff --git a/compiler/rustc_ast_lowering/messages.ftl b/compiler/rustc_ast_lowering/messages.ftl
index e87cf05713cd3..4005bf4bd7bf5 100644
--- a/compiler/rustc_ast_lowering/messages.ftl
+++ b/compiler/rustc_ast_lowering/messages.ftl
@@ -48,6 +48,11 @@ ast_lowering_clobber_abi_not_supported =
 
 ast_lowering_closure_cannot_be_static = closures cannot be static
 
+ast_lowering_continue_labeled_block =
+    `continue` pointing to a labeled block
+    .label = labeled blocks cannot be `continue`'d
+    .block_label = labeled block the `continue` points to
+
 ast_lowering_coroutine_too_many_parameters =
     too many parameters for a coroutine (expected 0 or 1 parameters)
 
diff --git a/compiler/rustc_ast_lowering/src/errors.rs b/compiler/rustc_ast_lowering/src/errors.rs
index 834409da6750a..c79cb90450efc 100644
--- a/compiler/rustc_ast_lowering/src/errors.rs
+++ b/compiler/rustc_ast_lowering/src/errors.rs
@@ -405,3 +405,13 @@ pub(crate) struct AsyncBoundOnlyForFnTraits {
     #[primary_span]
     pub span: Span,
 }
+
+#[derive(Diagnostic)]
+#[diag(ast_lowering_continue_labeled_block, code = E0696)]
+pub struct ContinueLabeledBlock {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+    #[label(ast_lowering_block_label)]
+    pub block_span: Span,
+}
diff --git a/compiler/rustc_ast_lowering/src/expr.rs b/compiler/rustc_ast_lowering/src/expr.rs
index 9950db4784b9c..9c497de8642c9 100644
--- a/compiler/rustc_ast_lowering/src/expr.rs
+++ b/compiler/rustc_ast_lowering/src/expr.rs
@@ -8,6 +8,7 @@ use super::errors::{
 };
 use super::ResolverAstLoweringExt;
 use super::{ImplTraitContext, LoweringContext, ParamMode, ParenthesizedGenericArgs};
+use crate::errors::ContinueLabeledBlock;
 use crate::{FnDeclKind, ImplTraitPosition};
 use rustc_ast::ptr::P as AstP;
 use rustc_ast::*;
@@ -283,7 +284,26 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     hir::ExprKind::Break(self.lower_jump_destination(e.id, *opt_label), opt_expr)
                 }
                 ExprKind::Continue(opt_label) => {
-                    hir::ExprKind::Continue(self.lower_jump_destination(e.id, *opt_label))
+                    if let Some(_) = opt_label {
+                        if let Some((_, is_loop, block_span)) = self.resolver.get_label_res(e.id) {
+                            if is_loop {
+                                hir::ExprKind::Continue(
+                                    self.lower_jump_destination(e.id, *opt_label),
+                                )
+                            } else {
+                                hir::ExprKind::Err(
+                                    self.dcx().emit_err(ContinueLabeledBlock {
+                                        span: e.span,
+                                        block_span,
+                                    }),
+                                )
+                            }
+                        } else {
+                            hir::ExprKind::Continue(self.lower_jump_destination(e.id, *opt_label))
+                        }
+                    } else {
+                        hir::ExprKind::Continue(self.lower_jump_destination(e.id, *opt_label))
+                    }
                 }
                 ExprKind::Ret(e) => {
                     let e = e.as_ref().map(|x| self.lower_expr(x));
@@ -1429,8 +1449,8 @@ impl<'hir> LoweringContext<'_, 'hir> {
     fn lower_loop_destination(&mut self, destination: Option<(NodeId, Label)>) -> hir::Destination {
         let target_id = match destination {
             Some((id, _)) => {
-                if let Some(loop_id) = self.resolver.get_label_res(id) {
-                    Ok(self.lower_node_id(loop_id))
+                if let Some((id, _is_loop, _)) = self.resolver.get_label_res(id) {
+                    Ok(self.lower_node_id(id))
                 } else {
                     Err(hir::LoopIdError::UnresolvedLabel)
                 }
diff --git a/compiler/rustc_ast_lowering/src/lib.rs b/compiler/rustc_ast_lowering/src/lib.rs
index a5be91bb87209..885bc63f659b1 100644
--- a/compiler/rustc_ast_lowering/src/lib.rs
+++ b/compiler/rustc_ast_lowering/src/lib.rs
@@ -229,7 +229,7 @@ impl ResolverAstLowering {
     }
 
     /// Obtains resolution for a label with the given `NodeId`.
-    fn get_label_res(&self, id: NodeId) -> Option<NodeId> {
+    fn get_label_res(&self, id: NodeId) -> Option<(NodeId, bool, Span)> {
         self.label_res_map.get(&id).copied()
     }
 
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index 30409e990e13c..1d37bd02f48c0 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -200,7 +200,8 @@ pub struct ResolverAstLowering {
     /// Resolutions for import nodes, which have multiple resolutions in different namespaces.
     pub import_res_map: NodeMap<hir::def::PerNS<Option<Res<ast::NodeId>>>>,
     /// Resolutions for labels (node IDs of their corresponding blocks or loops).
-    pub label_res_map: NodeMap<ast::NodeId>,
+    /// The boolean stores if the node is loop. The span is the span of the node.
+    pub label_res_map: NodeMap<(ast::NodeId, bool, Span)>,
     /// Resolutions for lifetimes.
     pub lifetimes_res_map: NodeMap<LifetimeRes>,
     /// Lifetime parameters that lowering will have to introduce.
diff --git a/compiler/rustc_resolve/src/late.rs b/compiler/rustc_resolve/src/late.rs
index 2f4da29133f1b..bb5782ac30e18 100644
--- a/compiler/rustc_resolve/src/late.rs
+++ b/compiler/rustc_resolve/src/late.rs
@@ -658,7 +658,7 @@ struct LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
     last_block_rib: Option<Rib<'a>>,
 
     /// The current set of local scopes, for labels.
-    label_ribs: Vec<Rib<'a, NodeId>>,
+    label_ribs: Vec<Rib<'a, (NodeId, bool, Span)>>,
 
     /// The current set of local scopes for lifetimes.
     lifetime_ribs: Vec<LifetimeRib>,
@@ -2215,7 +2215,10 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
 
     /// Searches the current set of local scopes for labels. Returns the `NodeId` of the resolved
     /// label and reports an error if the label is not found or is unreachable.
-    fn resolve_label(&mut self, mut label: Ident) -> Result<(NodeId, Span), ResolutionError<'a>> {
+    fn resolve_label(
+        &mut self,
+        mut label: Ident,
+    ) -> Result<((NodeId, bool, Span), Span), ResolutionError<'a>> {
         let mut suggestion = None;
 
         for i in (0..self.label_ribs.len()).rev() {
@@ -4184,7 +4187,14 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
         Ok(Some(result))
     }
 
-    fn with_resolved_label(&mut self, label: Option<Label>, id: NodeId, f: impl FnOnce(&mut Self)) {
+    fn with_resolved_label(
+        &mut self,
+        label: Option<Label>,
+        id: NodeId,
+        is_loop: bool,
+        span: Span,
+        f: impl FnOnce(&mut Self),
+    ) {
         if let Some(label) = label {
             if label.ident.as_str().as_bytes()[1] != b'_' {
                 self.diagnostic_metadata.unused_labels.insert(id, label.ident.span);
@@ -4196,7 +4206,7 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
 
             self.with_label_rib(RibKind::Normal, |this| {
                 let ident = label.ident.normalize_to_macro_rules();
-                this.label_ribs.last_mut().unwrap().bindings.insert(ident, id);
+                this.label_ribs.last_mut().unwrap().bindings.insert(ident, (id, is_loop, span));
                 f(this);
             });
         } else {
@@ -4204,8 +4214,14 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
         }
     }
 
-    fn resolve_labeled_block(&mut self, label: Option<Label>, id: NodeId, block: &'ast Block) {
-        self.with_resolved_label(label, id, |this| this.visit_block(block));
+    fn resolve_labeled_block(
+        &mut self,
+        label: Option<Label>,
+        id: NodeId,
+        block: &'ast Block,
+        is_loop: bool,
+    ) {
+        self.with_resolved_label(label, id, is_loop, block.span, |this| this.visit_block(block));
     }
 
     fn resolve_block(&mut self, block: &'ast Block) {
@@ -4348,10 +4364,10 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
 
             ExprKind::Break(Some(label), _) | ExprKind::Continue(Some(label)) => {
                 match self.resolve_label(label.ident) {
-                    Ok((node_id, _)) => {
+                    Ok((node, _)) => {
                         // Since this res is a label, it is never read.
-                        self.r.label_res_map.insert(expr.id, node_id);
-                        self.diagnostic_metadata.unused_labels.remove(&node_id);
+                        self.r.label_res_map.insert(expr.id, node);
+                        self.diagnostic_metadata.unused_labels.remove(&node.0);
                     }
                     Err(error) => {
                         self.report_error(label.ident.span, error);
@@ -4386,11 +4402,11 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
             }
 
             ExprKind::Loop(ref block, label, _) => {
-                self.resolve_labeled_block(label, expr.id, block)
+                self.resolve_labeled_block(label, expr.id, block, true)
             }
 
             ExprKind::While(ref cond, ref block, label) => {
-                self.with_resolved_label(label, expr.id, |this| {
+                self.with_resolved_label(label, expr.id, true, block.span, |this| {
                     this.with_rib(ValueNS, RibKind::Normal, |this| {
                         let old = this.diagnostic_metadata.in_if_condition.replace(cond);
                         this.visit_expr(cond);
@@ -4404,11 +4420,13 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
                 self.visit_expr(iter);
                 self.with_rib(ValueNS, RibKind::Normal, |this| {
                     this.resolve_pattern_top(pat, PatternSource::For);
-                    this.resolve_labeled_block(label, expr.id, body);
+                    this.resolve_labeled_block(label, expr.id, body, true);
                 });
             }
 
-            ExprKind::Block(ref block, label) => self.resolve_labeled_block(label, block.id, block),
+            ExprKind::Block(ref block, label) => {
+                self.resolve_labeled_block(label, block.id, block, false)
+            }
 
             // Equivalent to `visit::walk_expr` + passing some context to children.
             ExprKind::Field(ref subexpression, _) => {
diff --git a/compiler/rustc_resolve/src/late/diagnostics.rs b/compiler/rustc_resolve/src/late/diagnostics.rs
index 51723fc81a01f..251dd397dbc5a 100644
--- a/compiler/rustc_resolve/src/late/diagnostics.rs
+++ b/compiler/rustc_resolve/src/late/diagnostics.rs
@@ -951,7 +951,7 @@ impl<'a: 'ast, 'ast, 'tcx> LateResolutionVisitor<'a, '_, 'ast, 'tcx> {
         if let Some(err_code) = err.code {
             if err_code == E0425 {
                 for label_rib in &self.label_ribs {
-                    for (label_ident, node_id) in &label_rib.bindings {
+                    for (label_ident, (node_id, _, _)) in &label_rib.bindings {
                         let ident = path.last().unwrap().ident;
                         if format!("'{ident}") == label_ident.to_string() {
                             err.span_label(label_ident.span, "a label with a similar name exists");
diff --git a/compiler/rustc_resolve/src/lib.rs b/compiler/rustc_resolve/src/lib.rs
index a9b6703f3ab68..24a26cb6d4356 100644
--- a/compiler/rustc_resolve/src/lib.rs
+++ b/compiler/rustc_resolve/src/lib.rs
@@ -999,7 +999,8 @@ pub struct Resolver<'a, 'tcx> {
     /// Resolutions for import nodes, which have multiple resolutions in different namespaces.
     import_res_map: NodeMap<PerNS<Option<Res>>>,
     /// Resolutions for labels (node IDs of their corresponding blocks or loops).
-    label_res_map: NodeMap<NodeId>,
+    /// The boolean stores if the node is loop. The span is the span of the node.
+    label_res_map: NodeMap<(NodeId, bool, Span)>,
     /// Resolutions for lifetimes.
     lifetimes_res_map: NodeMap<LifetimeRes>,
     /// Lifetime parameters that lowering will have to introduce.
diff --git a/tests/ui/lowering/cont-in-block/cont-in-fn-issue-113379.rs b/tests/ui/lowering/cont-in-block/cont-in-fn-issue-113379.rs
new file mode 100644
index 0000000000000..6ea6eb8132ae3
--- /dev/null
+++ b/tests/ui/lowering/cont-in-block/cont-in-fn-issue-113379.rs
@@ -0,0 +1,28 @@
+#![allow(incomplete_features)]
+#![feature(adt_const_params)]
+
+trait Trait<const S: &'static str> {}
+
+struct Bug<T>
+where
+    T: Trait<
+        {
+            'b: { //~ ERROR [E0308]
+                continue 'b; //~ ERROR [E0696]
+            }
+        },
+    >,
+{
+    t: T,
+}
+
+fn f() -> impl Sized {
+    'b: {
+        continue 'b;
+        //~^ ERROR [E0696]
+    }
+}
+
+fn main() {
+    f();
+}
diff --git a/tests/ui/lowering/cont-in-block/cont-in-fn-issue-113379.stderr b/tests/ui/lowering/cont-in-block/cont-in-fn-issue-113379.stderr
new file mode 100644
index 0000000000000..c0cf1cbe4c59f
--- /dev/null
+++ b/tests/ui/lowering/cont-in-block/cont-in-fn-issue-113379.stderr
@@ -0,0 +1,31 @@
+error[E0696]: `continue` pointing to a labeled block
+  --> $DIR/cont-in-fn-issue-113379.rs:11:17
+   |
+LL | /             'b: {
+LL | |                 continue 'b;
+   | |                 ^^^^^^^^^^^ labeled blocks cannot be `continue`'d
+LL | |             }
+   | |_____________- labeled block the `continue` points to
+
+error[E0696]: `continue` pointing to a labeled block
+  --> $DIR/cont-in-fn-issue-113379.rs:21:9
+   |
+LL | /     'b: {
+LL | |         continue 'b;
+   | |         ^^^^^^^^^^^ labeled blocks cannot be `continue`'d
+LL | |
+LL | |     }
+   | |_____- labeled block the `continue` points to
+
+error[E0308]: mismatched types
+  --> $DIR/cont-in-fn-issue-113379.rs:10:13
+   |
+LL | /             'b: {
+LL | |                 continue 'b;
+LL | |             }
+   | |_____________^ expected `&str`, found `()`
+
+error: aborting due to 3 previous errors
+
+Some errors have detailed explanations: E0308, E0696.
+For more information about an error, try `rustc --explain E0308`.
diff --git a/tests/ui/lowering/cont-in-block/cont-in-match-arm-issue-121623.rs b/tests/ui/lowering/cont-in-block/cont-in-match-arm-issue-121623.rs
new file mode 100644
index 0000000000000..93ff1d5f8f206
--- /dev/null
+++ b/tests/ui/lowering/cont-in-block/cont-in-match-arm-issue-121623.rs
@@ -0,0 +1,8 @@
+fn main() {
+    match () {
+        _ => 'b: {
+            continue 'b;
+            //~^ ERROR [E0696]
+        }
+    }
+}
diff --git a/tests/ui/lowering/cont-in-block/cont-in-match-arm-issue-121623.stderr b/tests/ui/lowering/cont-in-block/cont-in-match-arm-issue-121623.stderr
new file mode 100644
index 0000000000000..ffe7331031d7a
--- /dev/null
+++ b/tests/ui/lowering/cont-in-block/cont-in-match-arm-issue-121623.stderr
@@ -0,0 +1,14 @@
+error[E0696]: `continue` pointing to a labeled block
+  --> $DIR/cont-in-match-arm-issue-121623.rs:4:13
+   |
+LL |           _ => 'b: {
+   |  ______________-
+LL | |             continue 'b;
+   | |             ^^^^^^^^^^^ labeled blocks cannot be `continue`'d
+LL | |
+LL | |         }
+   | |_________- labeled block the `continue` points to
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0696`.