Fix Error Messages for break Inside Coroutines

Previously, `break` inside `gen` blocks and functions
were incorrectly identified to be enclosed by a closure.

This PR fixes it by displaying an appropriate error message
for async blocks, async closures, async functions, gen blocks,
gen closures, gen functions, async gen blocks, async gen closures
and async gen functions.

Note: gen closure and async gen closure are not supported by the
compiler yet but I have added an error message here assuming that
they might be implemented in the future.

Also, fixes grammar in a few places by replacing
`inside of a $coroutine` with `inside a $coroutine`.

Author: veera-sivarajan

Diff for: compiler/rustc_passes/messages.ftl

@@ -52,16 +52,16 @@ passes_attr_only_in_functions =
 passes_both_ffi_const_and_pure =
     `#[ffi_const]` function cannot be `#[ffi_pure]`
 
-passes_break_inside_async_block =
-    `{$name}` inside of an `async` block
-    .label = cannot `{$name}` inside of an `async` block
-    .async_block_label = enclosing `async` block
-
 passes_break_inside_closure =
     `{$name}` inside of a closure
     .label = cannot `{$name}` inside of a closure
     .closure_label = enclosing closure
 
+passes_break_inside_coroutine =
+    `{$name}` inside `{$kind}` {$source}
+    .label = cannot `{$name}` inside `{$kind}` {$source}
+    .coroutine_label = enclosing `{$kind}` {$source}
+
 passes_break_non_loop =
     `break` with value from a `{$kind}` loop
     .label = can only break with a value inside `loop` or breakable block

Diff for: compiler/rustc_passes/src/errors.rs

@@ -1086,14 +1086,16 @@ pub struct BreakInsideClosure<'a> {
 }
 
 #[derive(Diagnostic)]
-#[diag(passes_break_inside_async_block, code = E0267)]
-pub struct BreakInsideAsyncBlock<'a> {
+#[diag(passes_break_inside_coroutine, code = E0267)]
+pub struct BreakInsideCoroutine<'a> {
     #[primary_span]
     #[label]
     pub span: Span,
-    #[label(passes_async_block_label)]
-    pub closure_span: Span,
+    #[label(passes_coroutine_label)]
+    pub coroutine_span: Span,
     pub name: &'a str,
+    pub kind: &'a str,
+    pub source: &'a str,
 }
 
 #[derive(Diagnostic)]

Diff for: compiler/rustc_passes/src/loops.rs

@@ -13,7 +13,7 @@ use rustc_span::hygiene::DesugaringKind;
 use rustc_span::{BytePos, Span};
 
 use crate::errors::{
-    BreakInsideAsyncBlock, BreakInsideClosure, BreakNonLoop, ContinueLabeledBlock, OutsideLoop,
+    BreakInsideClosure, BreakInsideCoroutine, BreakNonLoop, ContinueLabeledBlock, OutsideLoop,
     OutsideLoopSuggestion, UnlabeledCfInWhileCondition, UnlabeledInLabeledBlock,
 };
 
@@ -23,7 +23,7 @@ enum Context {
     Fn,
     Loop(hir::LoopSource),
     Closure(Span),
-    AsyncClosure(Span),
+    Coroutine { coroutine_span: Span, kind: hir::CoroutineDesugaring, source: hir::CoroutineSource },
     UnlabeledBlock(Span),
     LabeledBlock,
     Constant,
@@ -89,12 +89,10 @@ impl<'a, 'hir> Visitor<'hir> for CheckLoopVisitor<'a, 'hir> {
             hir::ExprKind::Closure(&hir::Closure {
                 ref fn_decl, body, fn_decl_span, kind, ..
             }) => {
-                // FIXME(coroutines): This doesn't handle coroutines correctly
                 let cx = match kind {
-                    hir::ClosureKind::Coroutine(hir::CoroutineKind::Desugared(
-                        hir::CoroutineDesugaring::Async,
-                        hir::CoroutineSource::Block,
-                    )) => AsyncClosure(fn_decl_span),
+                    hir::ClosureKind::Coroutine(hir::CoroutineKind::Desugared(kind, source)) => {
+                        Coroutine { coroutine_span: fn_decl_span, kind, source }
+                    }
                     _ => Closure(fn_decl_span),
                 };
                 self.visit_fn_decl(fn_decl);
@@ -227,8 +225,24 @@ impl<'a, 'hir> CheckLoopVisitor<'a, 'hir> {
             Closure(closure_span) => {
                 self.sess.dcx().emit_err(BreakInsideClosure { span, closure_span, name });
             }
-            AsyncClosure(closure_span) => {
-                self.sess.dcx().emit_err(BreakInsideAsyncBlock { span, closure_span, name });
+            Coroutine { coroutine_span, kind, source } => {
+                let kind = match kind {
+                    hir::CoroutineDesugaring::Async => "async",
+                    hir::CoroutineDesugaring::Gen => "gen",
+                    hir::CoroutineDesugaring::AsyncGen => "async gen",
+                };
+                let source = match source {
+                    hir::CoroutineSource::Block => "block",
+                    hir::CoroutineSource::Closure => "closure",
+                    hir::CoroutineSource::Fn => "function",
+                };
+                self.sess.dcx().emit_err(BreakInsideCoroutine {
+                    span,
+                    coroutine_span,
+                    name,
+                    kind,
+                    source,
+                });
             }
             UnlabeledBlock(block_span) if is_break && block_span.eq_ctxt(break_span) => {
                 let suggestion = Some(OutsideLoopSuggestion { block_span, break_span });