Merge pull request #26679 from Microsoft/improveGetTypeOfExpression

Improve control flow analysis of type assertions

src/compiler/checker.ts

@@ -21699,15 +21699,19 @@ namespace ts {
          * to cache the result.
          */
         function getTypeOfExpression(node: Expression, cache?: boolean) {
+            const expr = skipParentheses(node);
             // Optimize for the common case of a call to a function with a single non-generic call
             // signature where we can just fetch the return type without checking the arguments.
-            if (node.kind === SyntaxKind.CallExpression && (<CallExpression>node).expression.kind !== SyntaxKind.SuperKeyword && !isRequireCall(node, /*checkArgumentIsStringLiteralLike*/ true) && !isSymbolOrSymbolForCall(node)) {
-                const funcType = checkNonNullExpression((<CallExpression>node).expression);
+            if (expr.kind === SyntaxKind.CallExpression && (<CallExpression>expr).expression.kind !== SyntaxKind.SuperKeyword && !isRequireCall(expr, /*checkArgumentIsStringLiteralLike*/ true) && !isSymbolOrSymbolForCall(expr)) {
+                const funcType = checkNonNullExpression((<CallExpression>expr).expression);
                 const signature = getSingleCallSignature(funcType);
                 if (signature && !signature.typeParameters) {
                     return getReturnTypeOfSignature(signature);
                 }
             }
+            else if (expr.kind === SyntaxKind.TypeAssertionExpression || expr.kind === SyntaxKind.AsExpression) {
+                return getTypeFromTypeNode((<TypeAssertion>expr).type);
+            }
             // Otherwise simply call checkExpression. Ideally, the entire family of checkXXX functions
             // should have a parameter that indicates whether full error checking is required such that
             // we can perform the optimizations locally.

tests/baselines/reference/controlFlowSelfReferentialLoop.errors.txt

@@ -184,4 +184,24 @@ tests/cases/compiler/controlFlowSelfReferentialLoop.ts(17,29): error TS7006: Par
             b=II(b,c,d,a,x[k+9], S44,0xEB86D391);
         }
     }
-    export default md5;
+    export default md5;
+    
+    // Repro from #26655
+    
+    interface DataShape {
+      message: { id: string }
+    }
+    
+    function getObject(id: string | number) {
+      return {} as any
+    }
+    
+    ;(() => {
+      let id: string | number = 'a'
+      while (1) {
+        const data = getObject(id) as DataShape
+        const message = data.message
+        id = message.id
+      }
+    })()
+    

tests/baselines/reference/controlFlowSelfReferentialLoop.js

@@ -98,7 +98,27 @@ function md5(string:string): void {
         b=II(b,c,d,a,x[k+9], S44,0xEB86D391);
     }
 }
-export default md5;
+export default md5;
+
+// Repro from #26655
+
+interface DataShape {
+  message: { id: string }
+}
+
+function getObject(id: string | number) {
+  return {} as any
+}
+
+;(() => {
+  let id: string | number = 'a'
+  while (1) {
+    const data = getObject(id) as DataShape
+    const message = data.message
+    id = message.id
+  }
+})()
+
 
 //// [controlFlowSelfReferentialLoop.js]
 "use strict";
@@ -204,3 +224,15 @@ function md5(string) {
     }
 }
 exports["default"] = md5;
+function getObject(id) {
+    return {};
+}
+;
+(function () {
+    var id = 'a';
+    while (1) {
+        var data = getObject(id);
+        var message = data.message;
+        id = message.id;
+    }
+})();

tests/baselines/reference/controlFlowSelfReferentialLoop.symbols

@@ -831,3 +831,45 @@ function md5(string:string): void {
 export default md5;
 >md5 : Symbol(md5, Decl(controlFlowSelfReferentialLoop.ts, 0, 0))
 
+// Repro from #26655
+
+interface DataShape {
+>DataShape : Symbol(DataShape, Decl(controlFlowSelfReferentialLoop.ts, 99, 19))
+
+  message: { id: string }
+>message : Symbol(DataShape.message, Decl(controlFlowSelfReferentialLoop.ts, 103, 21))
+>id : Symbol(id, Decl(controlFlowSelfReferentialLoop.ts, 104, 12))
+}
+
+function getObject(id: string | number) {
+>getObject : Symbol(getObject, Decl(controlFlowSelfReferentialLoop.ts, 105, 1))
+>id : Symbol(id, Decl(controlFlowSelfReferentialLoop.ts, 107, 19))
+
+  return {} as any
+}
+
+;(() => {
+  let id: string | number = 'a'
+>id : Symbol(id, Decl(controlFlowSelfReferentialLoop.ts, 112, 5))
+
+  while (1) {
+    const data = getObject(id) as DataShape
+>data : Symbol(data, Decl(controlFlowSelfReferentialLoop.ts, 114, 9))
+>getObject : Symbol(getObject, Decl(controlFlowSelfReferentialLoop.ts, 105, 1))
+>id : Symbol(id, Decl(controlFlowSelfReferentialLoop.ts, 112, 5))
+>DataShape : Symbol(DataShape, Decl(controlFlowSelfReferentialLoop.ts, 99, 19))
+
+    const message = data.message
+>message : Symbol(message, Decl(controlFlowSelfReferentialLoop.ts, 115, 9))
+>data.message : Symbol(DataShape.message, Decl(controlFlowSelfReferentialLoop.ts, 103, 21))
+>data : Symbol(data, Decl(controlFlowSelfReferentialLoop.ts, 114, 9))
+>message : Symbol(DataShape.message, Decl(controlFlowSelfReferentialLoop.ts, 103, 21))
+
+    id = message.id
+>id : Symbol(id, Decl(controlFlowSelfReferentialLoop.ts, 112, 5))
+>message.id : Symbol(id, Decl(controlFlowSelfReferentialLoop.ts, 104, 12))
+>message : Symbol(message, Decl(controlFlowSelfReferentialLoop.ts, 115, 9))
+>id : Symbol(id, Decl(controlFlowSelfReferentialLoop.ts, 104, 12))
+  }
+})()
+

tests/baselines/reference/controlFlowSelfReferentialLoop.types

@@ -1260,3 +1260,54 @@ function md5(string:string): void {
 export default md5;
 >md5 : (string: string) => void
 
+// Repro from #26655
+
+interface DataShape {
+  message: { id: string }
+>message : { id: string; }
+>id : string
+}
+
+function getObject(id: string | number) {
+>getObject : (id: string | number) => any
+>id : string | number
+
+  return {} as any
+>{} as any : any
+>{} : {}
+}
+
+;(() => {
+>(() => {  let id: string | number = 'a'  while (1) {    const data = getObject(id) as DataShape    const message = data.message    id = message.id  }})() : void
+>(() => {  let id: string | number = 'a'  while (1) {    const data = getObject(id) as DataShape    const message = data.message    id = message.id  }}) : () => void
+>() => {  let id: string | number = 'a'  while (1) {    const data = getObject(id) as DataShape    const message = data.message    id = message.id  }} : () => void
+
+  let id: string | number = 'a'
+>id : string | number
+>'a' : "a"
+
+  while (1) {
+>1 : 1
+
+    const data = getObject(id) as DataShape
+>data : DataShape
+>getObject(id) as DataShape : DataShape
+>getObject(id) : any
+>getObject : (id: string | number) => any
+>id : string
+
+    const message = data.message
+>message : { id: string; }
+>data.message : { id: string; }
+>data : DataShape
+>message : { id: string; }
+
+    id = message.id
+>id = message.id : string
+>id : string | number
+>message.id : string
+>message : { id: string; }
+>id : string
+  }
+})()
+

tests/cases/compiler/controlFlowSelfReferentialLoop.ts

@@ -99,4 +99,23 @@ function md5(string:string): void {
         b=II(b,c,d,a,x[k+9], S44,0xEB86D391);
     }
 }
-export default md5;
+export default md5;
+
+// Repro from #26655
+
+interface DataShape {
+  message: { id: string }
+}
+
+function getObject(id: string | number) {
+  return {} as any
+}
+
+;(() => {
+  let id: string | number = 'a'
+  while (1) {
+    const data = getObject(id) as DataShape
+    const message = data.message
+    id = message.id
+  }
+})()