ignore Initial check if left of DestructuringAsignment (microsoft#20906)

Kingwl · mhegazy · commit a82d1f8580c8 · 2018-01-08T13:13:23.000-08:00
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
@@ -13333,6 +13333,7 @@ namespace ts {
             const declarationContainer = getControlFlowContainer(declaration);
             let flowContainer = getControlFlowContainer(node);
             const isOuterVariable = flowContainer !== declarationContainer;
+            const isSpreadDestructuringAsignmentTarget = node.parent && node.parent.parent && isSpreadAssignment(node.parent) && isDestructuringAssignmentTarget(node.parent.parent);
             // When the control flow originates in a function expression or arrow function and we are referencing
             // a const variable or parameter from an outer function, we extend the origin of the control flow
             // analysis to include the immediately enclosing function.
@@ -13344,7 +13345,7 @@ namespace ts {
             // We only look for uninitialized variables in strict null checking mode, and only when we can analyze
             // the entire control flow graph from the variable's declaration (i.e. when the flow container and
             // declaration container are the same).
-            const assumeInitialized = isParameter || isAlias || isOuterVariable ||
+            const assumeInitialized = isParameter || isAlias || isOuterVariable || isSpreadDestructuringAsignmentTarget ||
                 type !== autoType && type !== autoArrayType && (!strictNullChecks || (type.flags & TypeFlags.Any) !== 0 ||
                 isInTypeQuery(node) || node.parent.kind === SyntaxKind.ExportSpecifier) ||
                 node.parent.kind === SyntaxKind.NonNullExpression ||
diff --git a/tests/baselines/reference/destructuringAssignmentWithStrictNullChecks.js b/tests/baselines/reference/destructuringAssignmentWithStrictNullChecks.js
@@ -0,0 +1,17 @@
+//// [destructuringAssignmentWithStrictNullChecks.ts]
+let bar: {};
+({ ...bar } = {});
+
+
+//// [destructuringAssignmentWithStrictNullChecks.js]
+var __rest = (this && this.__rest) || function (s, e) {
+    var t = {};
+    for (var p in s) if (Object.prototype.hasOwnProperty.call(s, p) && e.indexOf(p) < 0)
+        t[p] = s[p];
+    if (s != null && typeof Object.getOwnPropertySymbols === "function")
+        for (var i = 0, p = Object.getOwnPropertySymbols(s); i < p.length; i++) if (e.indexOf(p[i]) < 0)
+            t[p[i]] = s[p[i]];
+    return t;
+};
+var bar;
+(bar = __rest({}, []));
diff --git a/tests/baselines/reference/destructuringAssignmentWithStrictNullChecks.symbols b/tests/baselines/reference/destructuringAssignmentWithStrictNullChecks.symbols
@@ -0,0 +1,7 @@
+=== tests/cases/compiler/destructuringAssignmentWithStrictNullChecks.ts ===
+let bar: {};
+>bar : Symbol(bar, Decl(destructuringAssignmentWithStrictNullChecks.ts, 0, 3))
+
+({ ...bar } = {});
+>bar : Symbol(bar, Decl(destructuringAssignmentWithStrictNullChecks.ts, 0, 3))
+
diff --git a/tests/baselines/reference/destructuringAssignmentWithStrictNullChecks.types b/tests/baselines/reference/destructuringAssignmentWithStrictNullChecks.types
@@ -0,0 +1,11 @@
+=== tests/cases/compiler/destructuringAssignmentWithStrictNullChecks.ts ===
+let bar: {};
+>bar : {}
+
+({ ...bar } = {});
+>({ ...bar } = {}) : {}
+>{ ...bar } = {} : {}
+>{ ...bar } : {}
+>bar : {}
+>{} : {}
+
diff --git a/tests/cases/compiler/destructuringAssignmentWithStrictNullChecks.ts b/tests/cases/compiler/destructuringAssignmentWithStrictNullChecks.ts
@@ -0,0 +1,3 @@
+// @strictNullChecks: true
+let bar: {};
+({ ...bar } = {});

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,3 @@`
	`1`	`+// @strictNullChecks: true`
	`2`	`+let bar: {};`
	`3`	`+({ ...bar } = {});`