Merge pull request microsoft#8845 from Microsoft/Fix8834

Fix microsoft#8834: exclude paramters and variables from flag checks

Author: mhegazy

src/compiler/checker.ts

@@ -14528,6 +14528,12 @@ namespace ts {
         }
 
         function areDeclarationFlagsIdentical(left: Declaration, right: Declaration) {
+            if ((left.kind === SyntaxKind.Parameter && right.kind === SyntaxKind.VariableDeclaration) ||
+                (left.kind === SyntaxKind.VariableDeclaration && right.kind === SyntaxKind.Parameter)) {
+                // Differences in optionality between parameters and variables are allowed.
+                return true;
+            }
+
             if (hasQuestionToken(left) !== hasQuestionToken(right)) {
                 return false;
             }

tests/baselines/reference/optionalParamterAndVariableDeclaration.js

@@ -0,0 +1,15 @@
+//// [optionalParamterAndVariableDeclaration.ts]
+class C {
+    constructor(options?: number) {
+        var options = (options || 0);
+    }
+}
+
+
+//// [optionalParamterAndVariableDeclaration.js]
+var C = (function () {
+    function C(options) {
+        var options = (options || 0);
+    }
+    return C;
+}());

tests/baselines/reference/optionalParamterAndVariableDeclaration.symbols

@@ -0,0 +1,13 @@
+=== tests/cases/compiler/optionalParamterAndVariableDeclaration.ts ===
+class C {
+>C : Symbol(C, Decl(optionalParamterAndVariableDeclaration.ts, 0, 0))
+
+    constructor(options?: number) {
+>options : Symbol(options, Decl(optionalParamterAndVariableDeclaration.ts, 1, 16), Decl(optionalParamterAndVariableDeclaration.ts, 2, 11))
+
+        var options = (options || 0);
+>options : Symbol(options, Decl(optionalParamterAndVariableDeclaration.ts, 1, 16), Decl(optionalParamterAndVariableDeclaration.ts, 2, 11))
+>options : Symbol(options, Decl(optionalParamterAndVariableDeclaration.ts, 1, 16), Decl(optionalParamterAndVariableDeclaration.ts, 2, 11))
+    }
+}
+

tests/baselines/reference/optionalParamterAndVariableDeclaration.types

@@ -0,0 +1,16 @@
+=== tests/cases/compiler/optionalParamterAndVariableDeclaration.ts ===
+class C {
+>C : C
+
+    constructor(options?: number) {
+>options : number
+
+        var options = (options || 0);
+>options : number
+>(options || 0) : number
+>options || 0 : number
+>options : number
+>0 : number
+    }
+}
+

tests/baselines/reference/optionalParamterAndVariableDeclaration2.errors.txt

@@ -0,0 +1,13 @@
+tests/cases/compiler/optionalParamterAndVariableDeclaration2.ts(4,13): error TS2403: Subsequent variable declarations must have the same type.  Variable 'options' must be of type 'number | undefined', but here has type 'number'.
+
+
+==== tests/cases/compiler/optionalParamterAndVariableDeclaration2.ts (1 errors) ====
+    
+    class C {
+        constructor(options?: number) {
+            var options = (options || 0);
+                ~~~~~~~
+!!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'options' must be of type 'number | undefined', but here has type 'number'.
+        }
+    }
+    

tests/baselines/reference/optionalParamterAndVariableDeclaration2.js

@@ -0,0 +1,16 @@
+//// [optionalParamterAndVariableDeclaration2.ts]
+
+class C {
+    constructor(options?: number) {
+        var options = (options || 0);
+    }
+}
+
+
+//// [optionalParamterAndVariableDeclaration2.js]
+var C = (function () {
+    function C(options) {
+        var options = (options || 0);
+    }
+    return C;
+}());

tests/cases/compiler/optionalParamterAndVariableDeclaration.ts

@@ -0,0 +1,5 @@
+class C {
+    constructor(options?: number) {
+        var options = (options || 0);
+    }
+}

tests/cases/compiler/optionalParamterAndVariableDeclaration2.ts

@@ -0,0 +1,7 @@
+// @strictNullChecks: true
+
+class C {
+    constructor(options?: number) {
+        var options = (options || 0);
+    }
+}