Improved error message for calling/constructing types

Author: dragomirtitian

src/compiler/checker.ts

@@ -22015,11 +22015,83 @@ namespace ts {
             return true;
         }
 
+        function invocationErrorDetails(apparentType: Type, kind: SignatureKind): DiagnosticMessageChain {
+            let errorInfo: DiagnosticMessageChain | undefined;
+            const isCall = kind === SignatureKind.Call;
+            if (apparentType.flags & TypeFlags.Union) {
+                const types = (apparentType as UnionType).types;
+                let hasSignatures = false;
+                for (const constituent of types) {
+                    const signatures = getSignaturesOfType(constituent, kind);
+                    if (signatures.length !== 0) {
+                        hasSignatures = true;
+                        if (errorInfo) {
+                            // Bail early if we already have an error, no chance of "No constituent of type is callable"
+                            break;
+                        }
+                    }
+                    else {
+                        // Error on the first non callable constituent only
+                        if (!errorInfo) {
+                            errorInfo = chainDiagnosticMessages(
+                                errorInfo,
+                                isCall ?
+                                    Diagnostics.Type_0_has_no_call_signatures :
+                                    Diagnostics.Type_0_has_no_construct_signatures,
+                                typeToString(constituent)
+                            );
+                            errorInfo = chainDiagnosticMessages(
+                                errorInfo,
+                                isCall ?
+                                    Diagnostics.Not_all_constituents_of_type_0_are_callable :
+                                    Diagnostics.Not_all_constituents_of_type_0_are_constructable,
+                                typeToString(apparentType)
+                            );
+                        }
+                        if (hasSignatures) {
+                            // Bail early if we already found a siganture, no chance of "No constituent of type is callable"
+                            break;
+                        }
+                    }
+                }
+                if (!hasSignatures) {
+                    errorInfo = chainDiagnosticMessages(
+                        /* detials */ undefined,
+                        isCall ?
+                            Diagnostics.No_constituent_of_type_0_is_callable :
+                            Diagnostics.No_constituent_of_type_0_is_constructable,
+                        typeToString(apparentType)
+                    );
+                }
+                if (!errorInfo) {
+                    errorInfo = chainDiagnosticMessages(
+                        errorInfo,
+                        isCall ?
+                            Diagnostics.Each_member_of_the_union_type_0_has_signatures_but_none_of_those_signatures_are_compatible_with_each_other :
+                            Diagnostics.Each_member_of_the_union_type_0_has_construct_signatures_but_none_of_those_signatures_are_compatible_with_each_other,
+                        typeToString(apparentType)
+                    );
+                }
+            }
+            else {
+                errorInfo = chainDiagnosticMessages(
+                    errorInfo,
+                    isCall ?
+                        Diagnostics.Type_0_has_no_call_signatures :
+                        Diagnostics.Type_0_has_no_construct_signatures,
+                    typeToString(apparentType)
+                );
+            }
+            return chainDiagnosticMessages(
+                errorInfo,
+                isCall ?
+                    Diagnostics.This_expression_is_not_callable :
+                    Diagnostics.This_expression_is_not_constructable
+            );
+        }
         function invocationError(node: Node, apparentType: Type, kind: SignatureKind, relatedInformation?: DiagnosticRelatedInformation) {
-            const diagnostic = error(node, (kind === SignatureKind.Call ?
-                Diagnostics.Cannot_invoke_an_expression_whose_type_lacks_a_call_signature_Type_0_has_no_compatible_call_signatures :
-                Diagnostics.Cannot_use_new_with_an_expression_whose_type_lacks_a_call_or_construct_signature
-            ), typeToString(apparentType));
+            const diagnostic: Diagnostic = createDiagnosticForNodeFromMessageChain(node, invocationErrorDetails(apparentType, kind));
+            diagnostics.add(diagnostic);
             invocationErrorRecovery(apparentType, kind, relatedInformation ? addRelatedInfo(diagnostic, relatedInformation) : diagnostic);
         }
 
@@ -22113,7 +22185,7 @@ namespace ts {
 
             const headMessage = getDiagnosticHeadMessageForDecoratorResolution(node);
             if (!callSignatures.length) {
-                let errorInfo = chainDiagnosticMessages(/*details*/ undefined, Diagnostics.Cannot_invoke_an_expression_whose_type_lacks_a_call_signature_Type_0_has_no_compatible_call_signatures, typeToString(apparentType));
+                let errorInfo = invocationErrorDetails(apparentType, SignatureKind.Call);
                 errorInfo = chainDiagnosticMessages(errorInfo, headMessage);
                 const diag = createDiagnosticForNodeFromMessageChain(node, errorInfo);
                 diagnostics.add(diag);

src/compiler/diagnosticMessages.json

@@ -1236,15 +1236,15 @@
         "category": "Error",
         "code": 2348
     },
-    "Cannot invoke an expression whose type lacks a call signature. Type '{0}' has no compatible call signatures.": {
+    "This expression is not callable.": {
         "category": "Error",
         "code": 2349
     },
     "Only a void function can be called with the 'new' keyword.": {
         "category": "Error",
         "code": 2350
     },
-    "Cannot use 'new' with an expression whose type lacks a call or construct signature.": {
+    "This expression is not constructable.": {
         "category": "Error",
         "code": 2351
     },
@@ -2621,6 +2621,38 @@
         "category": "Error",
         "code": 2754
     },
+    "No constituent of type '{0}' is callable.": {
+        "category": "Error",
+        "code": 2755
+    },
+    "Not all constituents of type '{0}' are callable.": {
+        "category": "Error",
+        "code": 2756
+    },
+    "Type '{0}' has no call signatures.": {
+        "category": "Error",
+        "code": 2757
+    },
+    "Each member of the union type '{0}' has signatures, but none of those signatures are compatible with each other.": {
+        "category": "Error",
+        "code": 2758
+    },
+    "No constituent of type '{0}' is constructable.": {
+        "category": "Error",
+        "code": 2759
+    },
+    "Not all constituents of type '{0}' are constructable.": {
+        "category": "Error",
+        "code": 2760
+    },
+    "Type '{0}' has no construct signatures.": {
+        "category": "Error",
+        "code": 2761
+    },
+    "Each member of the union type '{0}' has construct signatures, but none of those signatures are compatible with each other.": {
+        "category": "Error",
+        "code": 2762
+    },
 
     "Import declaration '{0}' is using private name '{1}'.": {
         "category": "Error",

src/services/codefixes/fixInvalidImportSyntax.ts

@@ -31,15 +31,15 @@ namespace ts.codefix {
 
     registerCodeFix({
         errorCodes: [
-            Diagnostics.Cannot_invoke_an_expression_whose_type_lacks_a_call_signature_Type_0_has_no_compatible_call_signatures.code,
-            Diagnostics.Cannot_use_new_with_an_expression_whose_type_lacks_a_call_or_construct_signature.code,
+            Diagnostics.This_expression_is_not_callable.code,
+            Diagnostics.This_expression_is_not_constructable.code,
         ],
         getCodeActions: getActionsForUsageOfInvalidImport
     });
 
     function getActionsForUsageOfInvalidImport(context: CodeFixContext): CodeFixAction[] | undefined {
         const sourceFile = context.sourceFile;
-        const targetKind = Diagnostics.Cannot_invoke_an_expression_whose_type_lacks_a_call_signature_Type_0_has_no_compatible_call_signatures.code === context.errorCode ? SyntaxKind.CallExpression : SyntaxKind.NewExpression;
+        const targetKind = Diagnostics.This_expression_is_not_callable.code === context.errorCode ? SyntaxKind.CallExpression : SyntaxKind.NewExpression;
         const node = findAncestor(getTokenAtPosition(sourceFile, context.span.start), a => a.kind === targetKind && a.getStart() === context.span.start && a.getEnd() === (context.span.start + context.span.length)) as CallExpression | NewExpression;
         if (!node) {
             return [];

tests/baselines/reference/betterErrorForAccidentalCall.errors.txt

@@ -1,39 +1,49 @@
-tests/cases/compiler/betterErrorForAccidentalCall.ts(3,1): error TS2349: Cannot invoke an expression whose type lacks a call signature. Type 'String' has no compatible call signatures.
-tests/cases/compiler/betterErrorForAccidentalCall.ts(5,1): error TS2349: Cannot invoke an expression whose type lacks a call signature. Type 'String' has no compatible call signatures.
-tests/cases/compiler/betterErrorForAccidentalCall.ts(7,1): error TS2349: Cannot invoke an expression whose type lacks a call signature. Type 'String' has no compatible call signatures.
-tests/cases/compiler/betterErrorForAccidentalCall.ts(10,1): error TS2349: Cannot invoke an expression whose type lacks a call signature. Type 'String' has no compatible call signatures.
-tests/cases/compiler/betterErrorForAccidentalCall.ts(13,1): error TS2349: Cannot invoke an expression whose type lacks a call signature. Type 'String' has no compatible call signatures.
+tests/cases/compiler/betterErrorForAccidentalCall.ts(3,1): error TS2349: This expression is not callable.
+  Type 'String' has no call signatures.
+tests/cases/compiler/betterErrorForAccidentalCall.ts(5,1): error TS2349: This expression is not callable.
+  Type 'String' has no call signatures.
+tests/cases/compiler/betterErrorForAccidentalCall.ts(7,1): error TS2349: This expression is not callable.
+  Type 'String' has no call signatures.
+tests/cases/compiler/betterErrorForAccidentalCall.ts(10,1): error TS2349: This expression is not callable.
+  Type 'String' has no call signatures.
+tests/cases/compiler/betterErrorForAccidentalCall.ts(13,1): error TS2349: This expression is not callable.
+  Type 'String' has no call signatures.
 
 
 ==== tests/cases/compiler/betterErrorForAccidentalCall.ts (5 errors) ====
     declare function foo(): string;
 
     foo()(1 as number).toString();
     ~~~~~~~~~~~~~~~~~~
-!!! error TS2349: Cannot invoke an expression whose type lacks a call signature. Type 'String' has no compatible call signatures.
+!!! error TS2349: This expression is not callable.
+!!! error TS2349:   Type 'String' has no call signatures.
 
     foo()   (1 as number).toString();
     ~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2349: Cannot invoke an expression whose type lacks a call signature. Type 'String' has no compatible call signatures.
+!!! error TS2349: This expression is not callable.
+!!! error TS2349:   Type 'String' has no call signatures.
 
     foo()
     ~~~~~
     (1 as number).toString();
     ~~~~~~~~~~~~~
-!!! error TS2349: Cannot invoke an expression whose type lacks a call signature. Type 'String' has no compatible call signatures.
+!!! error TS2349: This expression is not callable.
+!!! error TS2349:   Type 'String' has no call signatures.
 !!! related TS2734 tests/cases/compiler/betterErrorForAccidentalCall.ts:7:1: It is highly likely that you are missing a semicolon.
 
     foo()
     ~~~~~
         (1 + 2).toString();
     ~~~~~~~~~~~
-!!! error TS2349: Cannot invoke an expression whose type lacks a call signature. Type 'String' has no compatible call signatures.
+!!! error TS2349: This expression is not callable.
+!!! error TS2349:   Type 'String' has no call signatures.
 !!! related TS2734 tests/cases/compiler/betterErrorForAccidentalCall.ts:10:1: It is highly likely that you are missing a semicolon.
 
     foo()
     ~~~~~
         (<number>1).toString();
     ~~~~~~~~~~~~~~~
-!!! error TS2349: Cannot invoke an expression whose type lacks a call signature. Type 'String' has no compatible call signatures.
+!!! error TS2349: This expression is not callable.
+!!! error TS2349:   Type 'String' has no call signatures.
 !!! related TS2734 tests/cases/compiler/betterErrorForAccidentalCall.ts:13:1: It is highly likely that you are missing a semicolon.
 

tests/baselines/reference/callOnInstance.errors.txt

@@ -1,7 +1,8 @@
 tests/cases/compiler/callOnInstance.ts(1,18): error TS2300: Duplicate identifier 'D'.
 tests/cases/compiler/callOnInstance.ts(3,15): error TS2300: Duplicate identifier 'D'.
 tests/cases/compiler/callOnInstance.ts(7,25): error TS2554: Expected 0 arguments, but got 1.
-tests/cases/compiler/callOnInstance.ts(10,1): error TS2349: Cannot invoke an expression whose type lacks a call signature. Type 'C' has no compatible call signatures.
+tests/cases/compiler/callOnInstance.ts(10,1): error TS2349: This expression is not callable.
+  Type 'C' has no call signatures.
 
 
 ==== tests/cases/compiler/callOnInstance.ts (4 errors) ====
@@ -22,4 +23,5 @@ tests/cases/compiler/callOnInstance.ts(10,1): error TS2349: Cannot invoke an exp
     declare class C { constructor(value: number); }
     (new C(1))(); // Error for calling an instance
     ~~~~~~~~~~~~
-!!! error TS2349: Cannot invoke an expression whose type lacks a call signature. Type 'C' has no compatible call signatures.
+!!! error TS2349: This expression is not callable.
+!!! error TS2349:   Type 'C' has no call signatures.

tests/baselines/reference/computedPropertiesInDestructuring1.errors.txt

@@ -6,15 +6,17 @@ tests/cases/compiler/computedPropertiesInDestructuring1.ts(14,15): error TS2537:
 tests/cases/compiler/computedPropertiesInDestructuring1.ts(15,15): error TS2537: Type '{ bar: number; }' has no matching index signature for type 'string'.
 tests/cases/compiler/computedPropertiesInDestructuring1.ts(16,16): error TS2537: Type '{ bar: number; }' has no matching index signature for type 'string'.
 tests/cases/compiler/computedPropertiesInDestructuring1.ts(17,16): error TS2537: Type '{ bar: number; }' has no matching index signature for type 'string'.
-tests/cases/compiler/computedPropertiesInDestructuring1.ts(20,8): error TS2349: Cannot invoke an expression whose type lacks a call signature. Type 'String' has no compatible call signatures.
+tests/cases/compiler/computedPropertiesInDestructuring1.ts(20,8): error TS2349: This expression is not callable.
+  Type 'String' has no call signatures.
 tests/cases/compiler/computedPropertiesInDestructuring1.ts(20,8): error TS2538: Type 'any' cannot be used as an index type.
 tests/cases/compiler/computedPropertiesInDestructuring1.ts(21,8): error TS2538: Type 'any' cannot be used as an index type.
 tests/cases/compiler/computedPropertiesInDestructuring1.ts(21,12): error TS2339: Property 'toExponential' does not exist on type 'string'.
 tests/cases/compiler/computedPropertiesInDestructuring1.ts(24,4): error TS2537: Type '{ bar: string; }' has no matching index signature for type 'string'.
 tests/cases/compiler/computedPropertiesInDestructuring1.ts(28,4): error TS2537: Type '{ bar: string; }' has no matching index signature for type 'string'.
 tests/cases/compiler/computedPropertiesInDestructuring1.ts(30,4): error TS2537: Type '{ bar: string; }' has no matching index signature for type 'string'.
 tests/cases/compiler/computedPropertiesInDestructuring1.ts(31,4): error TS2537: Type '{ bar: string; }' has no matching index signature for type 'string'.
-tests/cases/compiler/computedPropertiesInDestructuring1.ts(33,4): error TS2349: Cannot invoke an expression whose type lacks a call signature. Type 'String' has no compatible call signatures.
+tests/cases/compiler/computedPropertiesInDestructuring1.ts(33,4): error TS2349: This expression is not callable.
+  Type 'String' has no call signatures.
 tests/cases/compiler/computedPropertiesInDestructuring1.ts(33,4): error TS2538: Type 'any' cannot be used as an index type.
 tests/cases/compiler/computedPropertiesInDestructuring1.ts(34,4): error TS2538: Type 'any' cannot be used as an index type.
 tests/cases/compiler/computedPropertiesInDestructuring1.ts(34,5): error TS2365: Operator '+' cannot be applied to types '1' and '{}'.
@@ -58,7 +60,8 @@ tests/cases/compiler/computedPropertiesInDestructuring1.ts(34,5): error TS2365:
     // report errors on type errors in computed properties used in destructuring
     let [{[foo()]: bar6}] = [{bar: "bar"}];
            ~~~~~
-!!! error TS2349: Cannot invoke an expression whose type lacks a call signature. Type 'String' has no compatible call signatures.
+!!! error TS2349: This expression is not callable.
+!!! error TS2349:   Type 'String' has no call signatures.
            ~~~~~
 !!! error TS2538: Type 'any' cannot be used as an index type.
     let [{[foo.toExponential()]: bar7}] = [{bar: "bar"}];
@@ -87,7 +90,8 @@ tests/cases/compiler/computedPropertiesInDestructuring1.ts(34,5): error TS2365:
 
     [{[foo()]: bar4}] = [{bar: "bar"}];
        ~~~~~
-!!! error TS2349: Cannot invoke an expression whose type lacks a call signature. Type 'String' has no compatible call signatures.
+!!! error TS2349: This expression is not callable.
+!!! error TS2349:   Type 'String' has no call signatures.
        ~~~~~
 !!! error TS2538: Type 'any' cannot be used as an index type.
     [{[(1 + {})]: bar4}] = [{bar: "bar"}];