Merge pull request #6498 from Microsoft/convertLoopWithMissingInitializer

do not crash if initializer in For-statement is missing

src/compiler/emitter.ts

@@ -2886,7 +2886,8 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
                     case SyntaxKind.ForStatement:
                     case SyntaxKind.ForInStatement:
                     case SyntaxKind.ForOfStatement:
-                        if ((<ForStatement | ForInStatement | ForOfStatement>node).initializer.kind === SyntaxKind.VariableDeclarationList) {
+                        const initializer = (<ForStatement | ForInStatement | ForOfStatement>node).initializer;
+                        if (initializer && initializer.kind === SyntaxKind.VariableDeclarationList) {
                             loopInitializer = <VariableDeclarationList>(<ForStatement | ForInStatement | ForOfStatement>node).initializer;
                         }
                         break;

tests/baselines/reference/capturedLetConstInLoop11.js

@@ -0,0 +1,35 @@
+//// [capturedLetConstInLoop11.ts]
+for (;;) {
+    let x = 1;
+    () => x;
+}
+
+function foo() {
+    for (;;) {
+        const a = 0;
+        switch(a) {
+            case 0: return () => a;
+        }
+    }
+}
+
+//// [capturedLetConstInLoop11.js]
+var _loop_1 = function() {
+    var x = 1;
+    (function () { return x; });
+};
+for (;;) {
+    _loop_1();
+}
+function foo() {
+    var _loop_2 = function() {
+        var a = 0;
+        switch (a) {
+            case 0: return { value: function () { return a; } };
+        }
+    };
+    for (;;) {
+        var state_2 = _loop_2();
+        if (typeof state_2 === "object") return state_2.value
+    }
+}

tests/baselines/reference/capturedLetConstInLoop11.symbols

@@ -0,0 +1,24 @@
+=== tests/cases/compiler/capturedLetConstInLoop11.ts ===
+for (;;) {
+    let x = 1;
+>x : Symbol(x, Decl(capturedLetConstInLoop11.ts, 1, 7))
+
+    () => x;
+>x : Symbol(x, Decl(capturedLetConstInLoop11.ts, 1, 7))
+}
+
+function foo() {
+>foo : Symbol(foo, Decl(capturedLetConstInLoop11.ts, 3, 1))
+
+    for (;;) {
+        const a = 0;
+>a : Symbol(a, Decl(capturedLetConstInLoop11.ts, 7, 13))
+
+        switch(a) {
+>a : Symbol(a, Decl(capturedLetConstInLoop11.ts, 7, 13))
+
+            case 0: return () => a;
+>a : Symbol(a, Decl(capturedLetConstInLoop11.ts, 7, 13))
+        }
+    }
+}

tests/baselines/reference/capturedLetConstInLoop11.types

@@ -0,0 +1,29 @@
+=== tests/cases/compiler/capturedLetConstInLoop11.ts ===
+for (;;) {
+    let x = 1;
+>x : number
+>1 : number
+
+    () => x;
+>() => x : () => number
+>x : number
+}
+
+function foo() {
+>foo : () => () => number
+
+    for (;;) {
+        const a = 0;
+>a : number
+>0 : number
+
+        switch(a) {
+>a : number
+
+            case 0: return () => a;
+>0 : number
+>() => a : () => number
+>a : number
+        }
+    }
+}

tests/baselines/reference/capturedLetConstInLoop11_ES6.js

@@ -0,0 +1,28 @@
+//// [capturedLetConstInLoop11_ES6.ts]
+for (;;) {
+    let x = 1;
+    () => x;
+}
+
+function foo() {
+    for (;;) {
+        const a = 0;
+        switch(a) {
+            case 0: return () => a;
+        }
+    }
+}
+
+//// [capturedLetConstInLoop11_ES6.js]
+for (;;) {
+    let x = 1;
+    (() => x);
+}
+function foo() {
+    for (;;) {
+        const a = 0;
+        switch (a) {
+            case 0: return () => a;
+        }
+    }
+}

tests/baselines/reference/capturedLetConstInLoop11_ES6.symbols

@@ -0,0 +1,24 @@
+=== tests/cases/compiler/capturedLetConstInLoop11_ES6.ts ===
+for (;;) {
+    let x = 1;
+>x : Symbol(x, Decl(capturedLetConstInLoop11_ES6.ts, 1, 7))
+
+    () => x;
+>x : Symbol(x, Decl(capturedLetConstInLoop11_ES6.ts, 1, 7))
+}
+
+function foo() {
+>foo : Symbol(foo, Decl(capturedLetConstInLoop11_ES6.ts, 3, 1))
+
+    for (;;) {
+        const a = 0;
+>a : Symbol(a, Decl(capturedLetConstInLoop11_ES6.ts, 7, 13))
+
+        switch(a) {
+>a : Symbol(a, Decl(capturedLetConstInLoop11_ES6.ts, 7, 13))
+
+            case 0: return () => a;
+>a : Symbol(a, Decl(capturedLetConstInLoop11_ES6.ts, 7, 13))
+        }
+    }
+}

tests/baselines/reference/capturedLetConstInLoop11_ES6.types

@@ -0,0 +1,29 @@
+=== tests/cases/compiler/capturedLetConstInLoop11_ES6.ts ===
+for (;;) {
+    let x = 1;
+>x : number
+>1 : number
+
+    () => x;
+>() => x : () => number
+>x : number
+}
+
+function foo() {
+>foo : () => () => number
+
+    for (;;) {
+        const a = 0;
+>a : number
+>0 : number
+
+        switch(a) {
+>a : number
+
+            case 0: return () => a;
+>0 : number
+>() => a : () => number
+>a : number
+        }
+    }
+}

tests/cases/compiler/capturedLetConstInLoop11.ts

@@ -0,0 +1,13 @@
+for (;;) {
+    let x = 1;
+    () => x;
+}
+
+function foo() {
+    for (;;) {
+        const a = 0;
+        switch(a) {
+            case 0: return () => a;
+        }
+    }
+}

tests/cases/compiler/capturedLetConstInLoop11_ES6.ts

@@ -0,0 +1,14 @@
+// @target: ES6
+for (;;) {
+    let x = 1;
+    () => x;
+}
+
+function foo() {
+    for (;;) {
+        const a = 0;
+        switch(a) {
+            case 0: return () => a;
+        }
+    }
+}