A break or continue naming a label no statement around it has is an error

tslang/lib/TypeScript/MLIRGenFunctions.cpp

@@ -2,6 +2,8 @@
 
 #include "MLIRGenImpl.h"
 
+#include "llvm/ADT/ScopeExit.h"
+
 namespace typescript
 {
 namespace mlirgen
@@ -1633,6 +1635,11 @@ namespace mlirgen
         SymbolTableScopeT varScope(symbolTable);
         BoundRefCacheScopeT boundRefCacheScope(boundRefMaterializedCache);
 
+        // the labels around a function are not the body's to jump to
+        auto outerLabels = std::move(activeLabels);
+        activeLabels.clear();
+        auto restoreLabels = llvm::make_scope_exit([&]() { activeLabels = std::move(outerLabels); });
+
         auto location = loc(functionLikeDeclarationBaseAST);
 
         // Debug Info

tslang/lib/TypeScript/MLIRGenImpl.h

@@ -14384,6 +14384,11 @@ class MLIRGenImpl
 
     Stages stage;
 
+    // The labels of the statements around the code being generated, innermost last: a labeled
+    // `break` or `continue` has to name one of them. A function body starts with none: a jump
+    // can't leave a function.
+    SmallVector<std::string> activeLabels;
+
 private:
     std::string label;
     mlir::Block* tempEntryBlock;

tslang/lib/TypeScript/MLIRGenStatements.cpp

@@ -6,6 +6,8 @@
 
 #include "mlir/Dialect/Async/IR/Async.h"
 
+#include "llvm/ADT/ScopeExit.h"
+
 #undef DEBUG_TYPE
 #define DEBUG_TYPE "mlir"
 
@@ -996,6 +998,9 @@ namespace mlirgen
                          kind == SyntaxKind::ForStatement || kind == SyntaxKind::ForInStatement ||
                          kind == SyntaxKind::ForOfStatement;
 
+        activeLabels.push_back(label);
+        auto popLabel = llvm::make_scope_exit([&]() { activeLabels.pop_back(); });
+
         if (noLabelOp)
         {
             return mlirGen(labeledStatementAST->statement, genContext);
@@ -1029,6 +1034,13 @@ namespace mlirgen
         auto location = loc(continueStatementAST);
 
         auto label = MLIRHelper::getName(continueStatementAST->label);
+        // a `continue` to the label of a block (not a loop) starts the block again: an extension
+        // TypeScript doesn't have (tests/00break_continue.ts)
+        if (!label.empty() && !llvm::is_contained(activeLabels, label))
+        {
+            emitError(location, "A 'continue' statement can only jump to a label of an enclosing statement");
+            return mlir::failure();
+        }
 
         EXIT_IF_FAILED(mlirGenScopeExit(location, DisposeDepth::LoopScope, label, &genContext));
 
@@ -1041,6 +1053,11 @@ namespace mlirgen
         auto location = loc(breakStatementAST);
 
         auto label = MLIRHelper::getName(breakStatementAST->label);
+        if (!label.empty() && !llvm::is_contained(activeLabels, label))
+        {
+            emitError(location, "A 'break' statement can only jump to a label of an enclosing statement");
+            return mlir::failure();
+        }
 
         EXIT_IF_FAILED(mlirGenScopeExit(location, DisposeDepth::LoopScope, label, &genContext));
 

tslang/test/tester/CMakeLists.txt

@@ -2698,6 +2698,23 @@ foreach(call_arity_case ${call_arity_cases})
                                     FAIL_REGULAR_EXPRESSION "Stack dump|Assertion failed")
 endforeach()
 
+# A `continue` or `break` naming a label that no statement around it has is an error (a label
+# outside the function doesn't count); it compiled to a jump with nowhere to go.
+add_test(NAME test-compile-diagnostic-location-continue-label
+         COMMAND $<TARGET_FILE:tslang> --emit=obj --no-default-lib -mm=none
+                 "${PROJECT_SOURCE_DIR}/test/tester/diagnostic-location/continue_label.ts"
+                 -o "${CMAKE_CURRENT_BINARY_DIR}/diagnostic-location-continue-label.obj")
+set_tests_properties(test-compile-diagnostic-location-continue-label
+                     PROPERTIES PASS_REGULAR_EXPRESSION "continue_label\\.ts:7:13: error: A 'continue' statement can only jump to a label of an enclosing statement"
+                                FAIL_REGULAR_EXPRESSION "Stack dump|Assertion failed|continue_label\\.ts:6:")
+add_test(NAME test-compile-diagnostic-location-break-label
+         COMMAND $<TARGET_FILE:tslang> --emit=obj --no-default-lib -mm=none
+                 "${PROJECT_SOURCE_DIR}/test/tester/diagnostic-location/break_label.ts"
+                 -o "${CMAKE_CURRENT_BINARY_DIR}/diagnostic-location-break-label.obj")
+set_tests_properties(test-compile-diagnostic-location-break-label
+                     PROPERTIES PASS_REGULAR_EXPRESSION "break_label\\.ts:7:17: error: A 'break' statement can only jump to a label of an enclosing statement"
+                                FAIL_REGULAR_EXPRESSION "Stack dump|Assertion failed|break_label\\.ts:10:")
+
 # Storing a fraction into a variable whose type was inferred from an integer literal (`let s = 0`
 # is an s32) drops it, and is warned about; the inference itself stays.
 foreach(truncation_case "global|3:1" "local|5:9")

tslang/test/tester/diagnostic-location/break_label.ts

@@ -0,0 +1,12 @@
+// A continue or break naming a label no statement around it has compiled with no error.
+
+function main() {
+    outer: for (let i = 0; i < 3; i++) {
+        const f = () => {
+            for (;;) {
+                break outer;
+            }
+        };
+        break outer;
+    }
+}

tslang/test/tester/diagnostic-location/continue_label.ts

@@ -0,0 +1,10 @@
+// A continue or break naming a label no statement around it has compiled with no error.
+
+function main() {
+    outer: for (let i = 0; i < 3; i++) {
+        for (let j = 0; j < 3; j++) {
+            if (j == 1) continue outer;
+            continue nolabel;
+        }
+    }
+}