Don’t use checkExpressionCached when checking spread element inside a loop

Author: andrewbranch

src/compiler/checker.ts

@@ -20708,7 +20708,7 @@ namespace ts {
                 // of the argument is a tuple type, spread the tuple elements into the argument list. We can
                 // call checkExpressionCached because spread expressions never have a contextual type.
                 const spreadArgument = <SpreadElement>args[length - 1];
-                const type = checkExpressionCached(spreadArgument.expression);
+                const type = flowLoopCount ? checkExpression(spreadArgument.expression) : checkExpressionCached(spreadArgument.expression);
                 if (isTupleType(type)) {
                     const typeArguments = (<TypeReference>type).typeArguments || emptyArray;
                     const restIndex = type.target.hasRestElement ? typeArguments.length - 1 : -1;

tests/baselines/reference/noImplicitAnyLoopCrash.errors.txt

@@ -0,0 +1,18 @@
+tests/cases/compiler/noImplicitAnyLoopCrash.ts(4,16): error TS2556: Expected 0 arguments, but got 1 or more.
+tests/cases/compiler/noImplicitAnyLoopCrash.ts(4,19): error TS2461: Type 'number' is not an array type.
+tests/cases/compiler/noImplicitAnyLoopCrash.ts(4,19): error TS2461: Type 'undefined' is not an array type.
+
+
+==== tests/cases/compiler/noImplicitAnyLoopCrash.ts (3 errors) ====
+    let foo = () => {};
+    let bar;
+    while (1) {
+        bar = ~foo(...bar);
+                   ~~~~~~
+!!! error TS2556: Expected 0 arguments, but got 1 or more.
+                      ~~~
+!!! error TS2461: Type 'number' is not an array type.
+                      ~~~
+!!! error TS2461: Type 'undefined' is not an array type.
+    }
+    

tests/baselines/reference/noImplicitAnyLoopCrash.js

@@ -0,0 +1,14 @@
+//// [noImplicitAnyLoopCrash.ts]
+let foo = () => {};
+let bar;
+while (1) {
+    bar = ~foo(...bar);
+}
+
+
+//// [noImplicitAnyLoopCrash.js]
+var foo = function () { };
+var bar;
+while (1) {
+    bar = ~foo.apply(void 0, bar);
+}

tests/baselines/reference/noImplicitAnyLoopCrash.symbols

@@ -0,0 +1,14 @@
+=== tests/cases/compiler/noImplicitAnyLoopCrash.ts ===
+let foo = () => {};
+>foo : Symbol(foo, Decl(noImplicitAnyLoopCrash.ts, 0, 3))
+
+let bar;
+>bar : Symbol(bar, Decl(noImplicitAnyLoopCrash.ts, 1, 3))
+
+while (1) {
+    bar = ~foo(...bar);
+>bar : Symbol(bar, Decl(noImplicitAnyLoopCrash.ts, 1, 3))
+>foo : Symbol(foo, Decl(noImplicitAnyLoopCrash.ts, 0, 3))
+>bar : Symbol(bar, Decl(noImplicitAnyLoopCrash.ts, 1, 3))
+}
+

tests/baselines/reference/noImplicitAnyLoopCrash.types

@@ -0,0 +1,21 @@
+=== tests/cases/compiler/noImplicitAnyLoopCrash.ts ===
+let foo = () => {};
+>foo : () => void
+>() => {} : () => void
+
+let bar;
+>bar : any
+
+while (1) {
+>1 : 1
+
+    bar = ~foo(...bar);
+>bar = ~foo(...bar) : number
+>bar : any
+>~foo(...bar) : number
+>foo(...bar) : void
+>foo : () => void
+>...bar : any
+>bar : number
+}
+

tests/cases/compiler/noImplicitAnyLoopCrash.ts

@@ -1,5 +1,6 @@
 // @noImplicitAny: true
-let foo = () => {};     // if you remove or change foo definition to not a function, bug disappears
-let bar;                // if you add type annotation here, bug disappears
-while (1)               // if you remove while, bug disappears
-    bar = ~foo(...bar); // if you remove unary or spread operator, bug disappears
+let foo = () => {};
+let bar;
+while (1) {
+    bar = ~foo(...bar);
+}