Merge pull request #10334 from yortus/narrow-from-any

Narrow from 'any' in most situations

Author: DanielRosenwasser

src/compiler/checker.ts

@@ -8548,10 +8548,6 @@ namespace ts {
                     }
                     return type;
                 }
-                // We never narrow type any in an instanceof guard
-                if (isTypeAny(type)) {
-                    return type;
-                }
 
                 // Check that right operand is a function type with a prototype property
                 const rightType = checkExpression(expr.right);
@@ -8569,6 +8565,11 @@ namespace ts {
                     }
                 }
 
+                // Don't narrow from 'any' if the target type is exactly 'Object' or 'Function'
+                if (isTypeAny(type) && (targetType === globalObjectType || targetType === globalFunctionType)) {
+                    return type;
+                }
+
                 if (!targetType) {
                     // Target type is type of construct signature
                     let constructSignatures: Signature[];
@@ -8615,14 +8616,20 @@ namespace ts {
             }
 
             function narrowTypeByTypePredicate(type: Type, callExpression: CallExpression, assumeTrue: boolean): Type {
-                if (type.flags & TypeFlags.Any || !hasMatchingArgument(callExpression, reference)) {
+                if (!hasMatchingArgument(callExpression, reference)) {
                     return type;
                 }
                 const signature = getResolvedSignature(callExpression);
                 const predicate = signature.typePredicate;
                 if (!predicate) {
                     return type;
                 }
+
+                // Don't narrow from 'any' if the predicate type is exactly 'Object' or 'Function'
+                if (isTypeAny(type) && (predicate.type === globalObjectType || predicate.type === globalFunctionType)) {
+                    return type;
+                }
+
                 if (isIdentifierTypePredicate(predicate)) {
                     const predicateArgument = callExpression.arguments[predicate.parameterIndex];
                     if (predicateArgument) {

tests/baselines/reference/narrowExceptionVariableInCatchClause.errors.txt

@@ -0,0 +1,33 @@
+tests/cases/conformance/types/any/narrowExceptionVariableInCatchClause.ts(11,17): error TS2339: Property 'doPanic' does not exist on type '{ type: "foo"; dontPanic(): any; }'.
+tests/cases/conformance/types/any/narrowExceptionVariableInCatchClause.ts(16,17): error TS2339: Property 'massage' does not exist on type 'Error'.
+
+
+==== tests/cases/conformance/types/any/narrowExceptionVariableInCatchClause.ts (2 errors) ====
+    declare function isFooError(x: any): x is { type: 'foo'; dontPanic(); };
+    
+    function tryCatch() {
+        try {
+            // do stuff...
+        }
+        catch (err) { // err is implicitly 'any' and cannot be annotated
+    
+            if (isFooError(err)) {
+                err.dontPanic(); // OK
+                err.doPanic(); // ERROR: Property 'doPanic' does not exist on type '{...}'
+                    ~~~~~~~
+!!! error TS2339: Property 'doPanic' does not exist on type '{ type: "foo"; dontPanic(): any; }'.
+            }
+    
+            else if (err instanceof Error) {
+                err.message;
+                err.massage; // ERROR: Property 'massage' does not exist on type 'Error'
+                    ~~~~~~~
+!!! error TS2339: Property 'massage' does not exist on type 'Error'.
+            }
+    
+            else {
+                throw err;
+            }
+        }
+    }
+    

tests/baselines/reference/narrowExceptionVariableInCatchClause.js

@@ -0,0 +1,44 @@
+//// [narrowExceptionVariableInCatchClause.ts]
+declare function isFooError(x: any): x is { type: 'foo'; dontPanic(); };
+
+function tryCatch() {
+    try {
+        // do stuff...
+    }
+    catch (err) { // err is implicitly 'any' and cannot be annotated
+
+        if (isFooError(err)) {
+            err.dontPanic(); // OK
+            err.doPanic(); // ERROR: Property 'doPanic' does not exist on type '{...}'
+        }
+
+        else if (err instanceof Error) {
+            err.message;
+            err.massage; // ERROR: Property 'massage' does not exist on type 'Error'
+        }
+
+        else {
+            throw err;
+        }
+    }
+}
+
+
+//// [narrowExceptionVariableInCatchClause.js]
+function tryCatch() {
+    try {
+    }
+    catch (err) {
+        if (isFooError(err)) {
+            err.dontPanic(); // OK
+            err.doPanic(); // ERROR: Property 'doPanic' does not exist on type '{...}'
+        }
+        else if (err instanceof Error) {
+            err.message;
+            err.massage; // ERROR: Property 'massage' does not exist on type 'Error'
+        }
+        else {
+            throw err;
+        }
+    }
+}

tests/baselines/reference/narrowFromAnyWithInstanceof.errors.txt

@@ -0,0 +1,33 @@
+tests/cases/conformance/types/any/narrowFromAnyWithInstanceof.ts(17,7): error TS2339: Property 'mesage' does not exist on type 'Error'.
+tests/cases/conformance/types/any/narrowFromAnyWithInstanceof.ts(22,7): error TS2339: Property 'getHuors' does not exist on type 'Date'.
+
+
+==== tests/cases/conformance/types/any/narrowFromAnyWithInstanceof.ts (2 errors) ====
+    declare var x: any;
+    
+    if (x instanceof Function) { // 'any' is not narrowed when target type is 'Function'
+        x();
+        x(1, 2, 3);
+        x("hello!");
+        x.prop;
+    }
+    
+    if (x instanceof Object) { // 'any' is not narrowed when target type is 'Object'
+        x.method();
+        x();
+    }
+    
+    if (x instanceof Error) { // 'any' is narrowed to types other than 'Function'/'Object'
+        x.message;
+        x.mesage;
+          ~~~~~~
+!!! error TS2339: Property 'mesage' does not exist on type 'Error'.
+    }
+    
+    if (x instanceof Date) {
+        x.getDate();
+        x.getHuors();
+          ~~~~~~~~
+!!! error TS2339: Property 'getHuors' does not exist on type 'Date'.
+    }
+    

tests/baselines/reference/narrowFromAnyWithInstanceof.js

@@ -0,0 +1,45 @@
+//// [narrowFromAnyWithInstanceof.ts]
+declare var x: any;
+
+if (x instanceof Function) { // 'any' is not narrowed when target type is 'Function'
+    x();
+    x(1, 2, 3);
+    x("hello!");
+    x.prop;
+}
+
+if (x instanceof Object) { // 'any' is not narrowed when target type is 'Object'
+    x.method();
+    x();
+}
+
+if (x instanceof Error) { // 'any' is narrowed to types other than 'Function'/'Object'
+    x.message;
+    x.mesage;
+}
+
+if (x instanceof Date) {
+    x.getDate();
+    x.getHuors();
+}
+
+
+//// [narrowFromAnyWithInstanceof.js]
+if (x instanceof Function) {
+    x();
+    x(1, 2, 3);
+    x("hello!");
+    x.prop;
+}
+if (x instanceof Object) {
+    x.method();
+    x();
+}
+if (x instanceof Error) {
+    x.message;
+    x.mesage;
+}
+if (x instanceof Date) {
+    x.getDate();
+    x.getHuors();
+}

tests/baselines/reference/narrowFromAnyWithTypePredicate.errors.txt

@@ -0,0 +1,50 @@
+tests/cases/conformance/types/any/narrowFromAnyWithTypePredicate.ts(22,7): error TS2339: Property 'method' does not exist on type '{}'.
+tests/cases/conformance/types/any/narrowFromAnyWithTypePredicate.ts(23,5): error TS2349: Cannot invoke an expression whose type lacks a call signature.
+tests/cases/conformance/types/any/narrowFromAnyWithTypePredicate.ts(28,7): error TS2339: Property 'mesage' does not exist on type 'Error'.
+tests/cases/conformance/types/any/narrowFromAnyWithTypePredicate.ts(33,7): error TS2339: Property 'getHuors' does not exist on type 'Date'.
+
+
+==== tests/cases/conformance/types/any/narrowFromAnyWithTypePredicate.ts (4 errors) ====
+    declare var x: any;
+    declare function isFunction(x): x is Function;
+    declare function isObject(x): x is Object;
+    declare function isAnything(x): x is {};
+    declare function isError(x): x is Error;
+    declare function isDate(x): x is Date;
+    
+    
+    if (isFunction(x)) { // 'any' is not narrowed when target type is 'Function'
+        x();
+        x(1, 2, 3);
+        x("hello!");
+        x.prop;
+    }
+    
+    if (isObject(x)) { // 'any' is not narrowed when target type is 'Object'
+        x.method();
+        x();
+    }
+    
+    if (isAnything(x)) { // 'any' is narrowed to types other than 'Function'/'Object' (including {})
+        x.method();
+          ~~~~~~
+!!! error TS2339: Property 'method' does not exist on type '{}'.
+        x();
+        ~~~
+!!! error TS2349: Cannot invoke an expression whose type lacks a call signature.
+    }
+    
+    if (isError(x)) { 
+        x.message;
+        x.mesage;
+          ~~~~~~
+!!! error TS2339: Property 'mesage' does not exist on type 'Error'.
+    }
+    
+    if (isDate(x)) {
+        x.getDate();
+        x.getHuors();
+          ~~~~~~~~
+!!! error TS2339: Property 'getHuors' does not exist on type 'Date'.
+    }
+    

tests/baselines/reference/narrowFromAnyWithTypePredicate.js

@@ -0,0 +1,60 @@
+//// [narrowFromAnyWithTypePredicate.ts]
+declare var x: any;
+declare function isFunction(x): x is Function;
+declare function isObject(x): x is Object;
+declare function isAnything(x): x is {};
+declare function isError(x): x is Error;
+declare function isDate(x): x is Date;
+
+
+if (isFunction(x)) { // 'any' is not narrowed when target type is 'Function'
+    x();
+    x(1, 2, 3);
+    x("hello!");
+    x.prop;
+}
+
+if (isObject(x)) { // 'any' is not narrowed when target type is 'Object'
+    x.method();
+    x();
+}
+
+if (isAnything(x)) { // 'any' is narrowed to types other than 'Function'/'Object' (including {})
+    x.method();
+    x();
+}
+
+if (isError(x)) { 
+    x.message;
+    x.mesage;
+}
+
+if (isDate(x)) {
+    x.getDate();
+    x.getHuors();
+}
+
+
+//// [narrowFromAnyWithTypePredicate.js]
+if (isFunction(x)) {
+    x();
+    x(1, 2, 3);
+    x("hello!");
+    x.prop;
+}
+if (isObject(x)) {
+    x.method();
+    x();
+}
+if (isAnything(x)) {
+    x.method();
+    x();
+}
+if (isError(x)) {
+    x.message;
+    x.mesage;
+}
+if (isDate(x)) {
+    x.getDate();
+    x.getHuors();
+}