Merge pull request #8443 from Microsoft/controlFlowAccessors

Include accessors in control flow type analysis

Author: ahejlsberg

src/compiler/checker.ts

@@ -9795,7 +9795,7 @@ namespace ts {
             }
 
             const propType = getTypeOfSymbol(prop);
-            if (node.kind !== SyntaxKind.PropertyAccessExpression || !(prop.flags & (SymbolFlags.Variable | SymbolFlags.Property)) || isAssignmentTarget(node)) {
+            if (node.kind !== SyntaxKind.PropertyAccessExpression || !(prop.flags & (SymbolFlags.Variable | SymbolFlags.Property | SymbolFlags.Accessor)) || isAssignmentTarget(node)) {
                 return propType;
             }
             const leftmostNode = getLeftmostIdentifierOrThis(node);

tests/baselines/reference/typeGuardsInProperties.types

@@ -57,18 +57,18 @@ class C1 {
 >pp2 : string
 
         strOrNum = typeof this.pp3 === "string" && this.pp3; // string | number
->strOrNum = typeof this.pp3 === "string" && this.pp3 : string | number
+>strOrNum = typeof this.pp3 === "string" && this.pp3 : string
 >strOrNum : string | number
->typeof this.pp3 === "string" && this.pp3 : string | number
+>typeof this.pp3 === "string" && this.pp3 : string
 >typeof this.pp3 === "string" : boolean
 >typeof this.pp3 : string
 >this.pp3 : string | number
 >this : this
 >pp3 : string | number
 >"string" : string
->this.pp3 : string | number
+>this.pp3 : string
 >this : this
->pp3 : string | number
+>pp3 : string
     }
 }
 var c1: C1;
@@ -90,18 +90,18 @@ strOrNum = typeof c1.pp2 === "string" && c1.pp2; // string | number
 >pp2 : string
 
 strOrNum = typeof c1.pp3 === "string" && c1.pp3; // string | number
->strOrNum = typeof c1.pp3 === "string" && c1.pp3 : string | number
+>strOrNum = typeof c1.pp3 === "string" && c1.pp3 : string
 >strOrNum : string | number
->typeof c1.pp3 === "string" && c1.pp3 : string | number
+>typeof c1.pp3 === "string" && c1.pp3 : string
 >typeof c1.pp3 === "string" : boolean
 >typeof c1.pp3 : string
 >c1.pp3 : string | number
 >c1 : C1
 >pp3 : string | number
 >"string" : string
->c1.pp3 : string | number
+>c1.pp3 : string
 >c1 : C1
->pp3 : string | number
+>pp3 : string
 
 var obj1: {
 >obj1 : { x: string | number; }

tests/baselines/reference/typeGuardsObjectMethods.types

@@ -172,16 +172,16 @@ strOrNum = typeof obj1.method(strOrNum) === "string" && obj1.method(strOrNum);
 
 // accessing getter property
 strOrNum = typeof obj1.prop === "string" && obj1.prop; 
->strOrNum = typeof obj1.prop === "string" && obj1.prop : string | number
+>strOrNum = typeof obj1.prop === "string" && obj1.prop : string
 >strOrNum : string | number
->typeof obj1.prop === "string" && obj1.prop : string | number
+>typeof obj1.prop === "string" && obj1.prop : string
 >typeof obj1.prop === "string" : boolean
 >typeof obj1.prop : string
 >obj1.prop : string | number
 >obj1 : { method(param: string | number): string | number; prop: string | number; }
 >prop : string | number
 >"string" : string
->obj1.prop : string | number
+>obj1.prop : string
 >obj1 : { method(param: string | number): string | number; prop: string | number; }
->prop : string | number
+>prop : string