Merge pull request microsoft#9003 from Microsoft/caseUndefinedAndNull

sandersn · sandersn · commit 5fef0804c8a0 · 2016-06-07T09:25:03.000-07:00
Allow case comparison to undefined and null in strict null checking mode
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
@@ -15110,7 +15110,7 @@ namespace ts {
                     // In a 'switch' statement, each 'case' expression must be of a type that is comparable
                     // to or from the type of the 'switch' expression.
                     const caseType = checkExpression(caseClause.expression);
-                    if (!isTypeComparableTo(expressionType, caseType)) {
+                    if (!isTypeEqualityComparableTo(expressionType, caseType)) {
                         // expressionType is not comparable to caseType, try the reversed check and report errors if it fails
                         checkTypeComparableTo(caseType, expressionType, caseClause.expression, /*headMessage*/ undefined);
                     }
diff --git a/tests/baselines/reference/equalityStrictNulls.errors.txt b/tests/baselines/reference/equalityStrictNulls.errors.txt
@@ -81,4 +81,14 @@ tests/cases/conformance/types/typeRelationships/comparable/equalityStrictNulls.t
 !!! error TS2365: Operator '<=' cannot be applied to types 'number' and 'undefined'.
         }
     }
+    function f5(x: string) {
+        switch(x) {
+            case null:
+                break;
+            case undefined:
+                break;
+            default:
+                return;
+        }
+    }
     
diff --git a/tests/baselines/reference/equalityStrictNulls.js b/tests/baselines/reference/equalityStrictNulls.js
@@ -67,6 +67,16 @@ function f4(x: number) {
     if (x <= undefined) {
     }
 }
+function f5(x: string) {
+    switch(x) {
+        case null:
+            break;
+        case undefined:
+            break;
+        default:
+            return;
+    }
+}
 
 
 //// [equalityStrictNulls.js]
@@ -134,3 +144,13 @@ function f4(x) {
     if (x <= undefined) {
     }
 }
+function f5(x) {
+    switch (x) {
+        case null:
+            break;
+        case undefined:
+            break;
+        default:
+            return;
+    }
+}
diff --git a/tests/cases/conformance/types/typeRelationships/comparable/equalityStrictNulls.ts b/tests/cases/conformance/types/typeRelationships/comparable/equalityStrictNulls.ts
@@ -67,3 +67,13 @@ function f4(x: number) {
     if (x <= undefined) {
     }
 }
+function f5(x: string) {
+    switch(x) {
+        case null:
+            break;
+        case undefined:
+            break;
+        default:
+            return;
+    }
+}

Original file line number	Diff line number	Diff line change
`@@ -15110,7 +15110,7 @@ namespace ts {`
`15110`	`15110`	`// In a 'switch' statement, each 'case' expression must be of a type that is comparable`
`15111`	`15111`	`// to or from the type of the 'switch' expression.`
`15112`	`15112`	`const caseType = checkExpression(caseClause.expression);`
`15113`		`- if (!isTypeComparableTo(expressionType, caseType)) {`
	`15113`	`+ if (!isTypeEqualityComparableTo(expressionType, caseType)) {`
`15114`	`15114`	`// expressionType is not comparable to caseType, try the reversed check and report errors if it fails`
`15115`	`15115`	`checkTypeComparableTo(caseType, expressionType, caseClause.expression, /headMessage/ undefined);`
`15116`	`15116`	`}`
Original file line number	Diff line number	Diff line change
`@@ -81,4 +81,14 @@ tests/cases/conformance/types/typeRelationships/comparable/equalityStrictNulls.t`
`81`	`81`	`!!! error TS2365: Operator '<=' cannot be applied to types 'number' and 'undefined'.`
`82`	`82`	`}`
`83`	`83`	`}`
	`84`	`+ function f5(x: string) {`
	`85`	`+ switch(x) {`
	`86`	`+ case null:`
	`87`	`+ break;`
	`88`	`+ case undefined:`
	`89`	`+ break;`
	`90`	`+ default:`
	`91`	`+ return;`
	`92`	`+ }`
	`93`	`+ }`
`84`	`94`
Original file line number	Diff line number	Diff line change
`@@ -67,3 +67,13 @@ function f4(x: number) {`
`67`	`67`	`if (x <= undefined) {`
`68`	`68`	`}`
`69`	`69`	`}`
	`70`	`+function f5(x: string) {`
	`71`	`+ switch(x) {`
	`72`	`+ case null:`
	`73`	`+ break;`
	`74`	`+ case undefined:`
	`75`	`+ break;`
	`76`	`+ default:`
	`77`	`+ return;`
	`78`	`+ }`
	`79`	`+}`