Introduce flattened error reporting for properties, call signatures, and construct signatures

scripts/processDiagnosticMessages.ts

@@ -6,6 +6,7 @@ interface DiagnosticDetails {
     code: number;
     reportsUnnecessary?: {};
     isEarly?: boolean;
+    elidedInCompatabilityPyramid?: boolean;
 }
 
 type InputDiagnosticMessageTable = Map<string, DiagnosticDetails>;
@@ -63,14 +64,15 @@ function buildInfoFileOutput(messageTable: InputDiagnosticMessageTable, inputFil
         "// generated from '" + inputFilePathRel + "' by '" + thisFilePathRel.replace(/\\/g, "/") + "'\r\n" +
         "/* @internal */\r\n" +
         "namespace ts {\r\n" +
-        "    function diag(code: number, category: DiagnosticCategory, key: string, message: string, reportsUnnecessary?: {}): DiagnosticMessage {\r\n" +
-        "        return { code, category, key, message, reportsUnnecessary };\r\n" +
+        "    function diag(code: number, category: DiagnosticCategory, key: string, message: string, reportsUnnecessary?: {}, elidedInCompatabilityPyramid?: boolean): DiagnosticMessage {\r\n" +
+        "        return { code, category, key, message, reportsUnnecessary, elidedInCompatabilityPyramid };\r\n" +
         "    }\r\n" +
         "    export const Diagnostics = {\r\n";
-    messageTable.forEach(({ code, category, reportsUnnecessary }, name) => {
+    messageTable.forEach(({ code, category, reportsUnnecessary, elidedInCompatabilityPyramid }, name) => {
         const propName = convertPropertyName(name);
         const argReportsUnnecessary = reportsUnnecessary ? `, /*reportsUnnecessary*/ ${reportsUnnecessary}` : "";
-        result += `        ${propName}: diag(${code}, DiagnosticCategory.${category}, "${createKey(propName, code)}", ${JSON.stringify(name)}${argReportsUnnecessary}),\r\n`;
+        const argElidedInCompatabilityPyramid = elidedInCompatabilityPyramid ? `${!reportsUnnecessary ? ", /*reportsUnnecessary*/ undefined" : ""}, /*elidedInCompatabilityPyramid*/ ${elidedInCompatabilityPyramid}` : "";
+        result += `        ${propName}: diag(${code}, DiagnosticCategory.${category}, "${createKey(propName, code)}", ${JSON.stringify(name)}${argReportsUnnecessary}${argElidedInCompatabilityPyramid}),\r\n`;
     });
 
     result += "    };\r\n}";

src/compiler/diagnosticMessages.json

@@ -1040,6 +1040,31 @@
         "code": 1357
     },
 
+    "The types of '{0}' are incompatible between these types.": {
+        "category": "Error",
+        "code": 2200
+    },
+    "Call signature return types '{0}' and '{1}' are incompatible.": {
+        "category": "Error",
+        "code": 2201,
+        "elidedInCompatabilityPyramid": true
+    },
+    "Construct signature return types '{0}' and '{1}' are incompatible.": {
+        "category": "Error",
+        "code": 2202,
+        "elidedInCompatabilityPyramid": true
+    },
+    "Call signatures with no arguments have incompatible return types '{0}' and '{1}'.": {
+        "category": "Error",
+        "code": 2203,
+        "elidedInCompatabilityPyramid": true
+    },
+    "Construct signatures with no arguments have incompatible return types '{0}' and '{1}'.": {
+        "category": "Error",
+        "code": 2204,
+        "elidedInCompatabilityPyramid": true
+    },
+
     "Duplicate identifier '{0}'.": {
         "category": "Error",
         "code": 2300

src/compiler/types.ts

@@ -4631,6 +4631,8 @@ namespace ts {
         code: number;
         message: string;
         reportsUnnecessary?: {};
+        /* @internal */
+        elidedInCompatabilityPyramid?: boolean;
     }
 
     /**

tests/baselines/reference/arrayLiterals3.errors.txt

@@ -8,10 +8,9 @@ tests/cases/conformance/expressions/arrayLiterals/arrayLiterals3.ts(17,5): error
 tests/cases/conformance/expressions/arrayLiterals/arrayLiterals3.ts(32,5): error TS2739: Type '(number[] | string[])[]' is missing the following properties from type 'tup': 0, 1
 tests/cases/conformance/expressions/arrayLiterals/arrayLiterals3.ts(33,5): error TS2739: Type 'number[]' is missing the following properties from type '[number, number, number]': 0, 1, 2
 tests/cases/conformance/expressions/arrayLiterals/arrayLiterals3.ts(34,5): error TS2322: Type '(string | number)[]' is not assignable to type 'myArray'.
-  Types of property 'pop' are incompatible.
-    Type '() => string | number' is not assignable to type '() => Number'.
-      Type 'string | number' is not assignable to type 'Number'.
-        Type 'string' is not assignable to type 'Number'.
+  The types of 'pop()' are incompatible between these types.
+    Type 'string | number' is not assignable to type 'Number'.
+      Type 'string' is not assignable to type 'Number'.
 
 
 ==== tests/cases/conformance/expressions/arrayLiterals/arrayLiterals3.ts (8 errors) ====
@@ -67,8 +66,7 @@ tests/cases/conformance/expressions/arrayLiterals/arrayLiterals3.ts(34,5): error
     var c2: myArray = [...temp1, ...temp];            // Error cannot assign (number|string)[] to number[]
         ~~
 !!! error TS2322: Type '(string | number)[]' is not assignable to type 'myArray'.
-!!! error TS2322:   Types of property 'pop' are incompatible.
-!!! error TS2322:     Type '() => string | number' is not assignable to type '() => Number'.
-!!! error TS2322:       Type 'string | number' is not assignable to type 'Number'.
-!!! error TS2322:         Type 'string' is not assignable to type 'Number'.
+!!! error TS2322:   The types of 'pop()' are incompatible between these types.
+!!! error TS2322:     Type 'string | number' is not assignable to type 'Number'.
+!!! error TS2322:       Type 'string' is not assignable to type 'Number'.
 

tests/baselines/reference/arrayOfSubtypeIsAssignableToReadonlyArray.errors.txt

@@ -1,10 +1,9 @@
 tests/cases/compiler/arrayOfSubtypeIsAssignableToReadonlyArray.ts(13,1): error TS2322: Type 'A[]' is not assignable to type 'readonly B[]'.
   Property 'b' is missing in type 'A' but required in type 'B'.
 tests/cases/compiler/arrayOfSubtypeIsAssignableToReadonlyArray.ts(18,1): error TS2322: Type 'C<A>' is not assignable to type 'readonly B[]'.
-  Types of property 'concat' are incompatible.
-    Type '{ (...items: ConcatArray<A>[]): A[]; (...items: (A | ConcatArray<A>)[]): A[]; }' is not assignable to type '{ (...items: ConcatArray<B>[]): B[]; (...items: (B | ConcatArray<B>)[]): B[]; }'.
-      Type 'A[]' is not assignable to type 'B[]'.
-        Type 'A' is not assignable to type 'B'.
+  The types of 'concat(...)' are incompatible between these types.
+    Type 'A[]' is not assignable to type 'B[]'.
+      Type 'A' is not assignable to type 'B'.
 
 
 ==== tests/cases/compiler/arrayOfSubtypeIsAssignableToReadonlyArray.ts (2 errors) ====
@@ -32,8 +31,7 @@ tests/cases/compiler/arrayOfSubtypeIsAssignableToReadonlyArray.ts(18,1): error T
     rrb = cra; // error: 'A' is not assignable to 'B'
     ~~~
 !!! error TS2322: Type 'C<A>' is not assignable to type 'readonly B[]'.
-!!! error TS2322:   Types of property 'concat' are incompatible.
-!!! error TS2322:     Type '{ (...items: ConcatArray<A>[]): A[]; (...items: (A | ConcatArray<A>)[]): A[]; }' is not assignable to type '{ (...items: ConcatArray<B>[]): B[]; (...items: (B | ConcatArray<B>)[]): B[]; }'.
-!!! error TS2322:       Type 'A[]' is not assignable to type 'B[]'.
-!!! error TS2322:         Type 'A' is not assignable to type 'B'.
+!!! error TS2322:   The types of 'concat(...)' are incompatible between these types.
+!!! error TS2322:     Type 'A[]' is not assignable to type 'B[]'.
+!!! error TS2322:       Type 'A' is not assignable to type 'B'.
 

tests/baselines/reference/assignFromBooleanInterface2.errors.txt

@@ -1,7 +1,6 @@
 tests/cases/conformance/types/primitives/boolean/assignFromBooleanInterface2.ts(14,1): error TS2322: Type 'NotBoolean' is not assignable to type 'Boolean'.
-  Types of property 'valueOf' are incompatible.
-    Type '() => Object' is not assignable to type '() => boolean'.
-      Type 'Object' is not assignable to type 'boolean'.
+  The types of 'valueOf()' are incompatible between these types.
+    Type 'Object' is not assignable to type 'boolean'.
 tests/cases/conformance/types/primitives/boolean/assignFromBooleanInterface2.ts(19,1): error TS2322: Type 'Boolean' is not assignable to type 'boolean'.
   'boolean' is a primitive, but 'Boolean' is a wrapper object. Prefer using 'boolean' when possible.
 tests/cases/conformance/types/primitives/boolean/assignFromBooleanInterface2.ts(20,1): error TS2322: Type 'NotBoolean' is not assignable to type 'boolean'.
@@ -24,9 +23,8 @@ tests/cases/conformance/types/primitives/boolean/assignFromBooleanInterface2.ts(
     a = b;
     ~
 !!! error TS2322: Type 'NotBoolean' is not assignable to type 'Boolean'.
-!!! error TS2322:   Types of property 'valueOf' are incompatible.
-!!! error TS2322:     Type '() => Object' is not assignable to type '() => boolean'.
-!!! error TS2322:       Type 'Object' is not assignable to type 'boolean'.
+!!! error TS2322:   The types of 'valueOf()' are incompatible between these types.
+!!! error TS2322:     Type 'Object' is not assignable to type 'boolean'.
 
     b = a;
     b = x;

tests/baselines/reference/asyncFunctionDeclaration15_es5.errors.txt

@@ -5,10 +5,9 @@ tests/cases/conformance/async/es5/functionDeclarations/asyncFunctionDeclaration1
 tests/cases/conformance/async/es5/functionDeclarations/asyncFunctionDeclaration15_es5.ts(8,23): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
 tests/cases/conformance/async/es5/functionDeclarations/asyncFunctionDeclaration15_es5.ts(9,23): error TS1055: Type 'PromiseLike' is not a valid async function return type in ES5/ES3 because it does not refer to a Promise-compatible constructor value.
 tests/cases/conformance/async/es5/functionDeclarations/asyncFunctionDeclaration15_es5.ts(10,23): error TS1055: Type 'typeof Thenable' is not a valid async function return type in ES5/ES3 because it does not refer to a Promise-compatible constructor value.
-  Type 'Thenable' is not assignable to type 'PromiseLike<T>'.
-    Types of property 'then' are incompatible.
-      Type '() => void' is not assignable to type '<TResult1 = T, TResult2 = never>(onfulfilled?: (value: T) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => PromiseLike<TResult1 | TResult2>'.
-        Type 'void' is not assignable to type 'PromiseLike<TResult1 | TResult2>'.
+  Construct signature return types 'Thenable' and 'PromiseLike<T>' are incompatible.
+    The types of 'then(...)' are incompatible between these types.
+      Type 'void' is not assignable to type 'PromiseLike<TResult1 | TResult2>'.
 tests/cases/conformance/async/es5/functionDeclarations/asyncFunctionDeclaration15_es5.ts(17,16): error TS1058: The return type of an async function must either be a valid promise or must not contain a callable 'then' member.
 tests/cases/conformance/async/es5/functionDeclarations/asyncFunctionDeclaration15_es5.ts(23,25): error TS1320: Type of 'await' operand must either be a valid promise or must not contain a callable 'then' member.
 
@@ -38,10 +37,9 @@ tests/cases/conformance/async/es5/functionDeclarations/asyncFunctionDeclaration1
     async function fn6(): Thenable { } // error
                           ~~~~~~~~
 !!! error TS1055: Type 'typeof Thenable' is not a valid async function return type in ES5/ES3 because it does not refer to a Promise-compatible constructor value.
-!!! error TS1055:   Type 'Thenable' is not assignable to type 'PromiseLike<T>'.
-!!! error TS1055:     Types of property 'then' are incompatible.
-!!! error TS1055:       Type '() => void' is not assignable to type '<TResult1 = T, TResult2 = never>(onfulfilled?: (value: T) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => PromiseLike<TResult1 | TResult2>'.
-!!! error TS1055:         Type 'void' is not assignable to type 'PromiseLike<TResult1 | TResult2>'.
+!!! error TS1055:   Construct signature return types 'Thenable' and 'PromiseLike<T>' are incompatible.
+!!! error TS1055:     The types of 'then(...)' are incompatible between these types.
+!!! error TS1055:       Type 'void' is not assignable to type 'PromiseLike<TResult1 | TResult2>'.
     async function fn7() { return; } // valid: Promise<void>
     async function fn8() { return 1; } // valid: Promise<number>
     async function fn9() { return null; } // valid: Promise<any>

tests/baselines/reference/bigintWithLib.errors.txt

@@ -4,15 +4,11 @@ tests/cases/compiler/bigintWithLib.ts(16,33): error TS2769: No overload matches
     Argument of type 'number[]' is not assignable to parameter of type 'number'.
   Overload 2 of 3, '(array: Iterable<bigint>): BigInt64Array', gave the following error.
     Argument of type 'number[]' is not assignable to parameter of type 'Iterable<bigint>'.
-      Types of property '[Symbol.iterator]' are incompatible.
-        Type '() => IterableIterator<number>' is not assignable to type '() => Iterator<bigint, any, undefined>'.
-          Type 'IterableIterator<number>' is not assignable to type 'Iterator<bigint, any, undefined>'.
-            Types of property 'next' are incompatible.
-              Type '(...args: [] | [undefined]) => IteratorResult<number, any>' is not assignable to type '(...args: [] | [undefined]) => IteratorResult<bigint, any>'.
-                Type 'IteratorResult<number, any>' is not assignable to type 'IteratorResult<bigint, any>'.
-                  Type 'IteratorYieldResult<number>' is not assignable to type 'IteratorResult<bigint, any>'.
-                    Type 'IteratorYieldResult<number>' is not assignable to type 'IteratorYieldResult<bigint>'.
-                      Type 'number' is not assignable to type 'bigint'.
+      The types of '[Symbol.iterator]().next(...)' are incompatible between these types.
+        Type 'IteratorResult<number, any>' is not assignable to type 'IteratorResult<bigint, any>'.
+          Type 'IteratorYieldResult<number>' is not assignable to type 'IteratorResult<bigint, any>'.
+            Type 'IteratorYieldResult<number>' is not assignable to type 'IteratorYieldResult<bigint>'.
+              Type 'number' is not assignable to type 'bigint'.
   Overload 3 of 3, '(buffer: ArrayBuffer | SharedArrayBuffer, byteOffset?: number, length?: number): BigInt64Array', gave the following error.
     Argument of type 'number[]' is not assignable to parameter of type 'ArrayBuffer | SharedArrayBuffer'.
       Type 'number[]' is missing the following properties from type 'SharedArrayBuffer': byteLength, [Symbol.species], [Symbol.toStringTag]
@@ -55,15 +51,11 @@ tests/cases/compiler/bigintWithLib.ts(43,26): error TS2345: Argument of type '12
 !!! error TS2769:     Argument of type 'number[]' is not assignable to parameter of type 'number'.
 !!! error TS2769:   Overload 2 of 3, '(array: Iterable<bigint>): BigInt64Array', gave the following error.
 !!! error TS2769:     Argument of type 'number[]' is not assignable to parameter of type 'Iterable<bigint>'.
-!!! error TS2769:       Types of property '[Symbol.iterator]' are incompatible.
-!!! error TS2769:         Type '() => IterableIterator<number>' is not assignable to type '() => Iterator<bigint, any, undefined>'.
-!!! error TS2769:           Type 'IterableIterator<number>' is not assignable to type 'Iterator<bigint, any, undefined>'.
-!!! error TS2769:             Types of property 'next' are incompatible.
-!!! error TS2769:               Type '(...args: [] | [undefined]) => IteratorResult<number, any>' is not assignable to type '(...args: [] | [undefined]) => IteratorResult<bigint, any>'.
-!!! error TS2769:                 Type 'IteratorResult<number, any>' is not assignable to type 'IteratorResult<bigint, any>'.
-!!! error TS2769:                   Type 'IteratorYieldResult<number>' is not assignable to type 'IteratorResult<bigint, any>'.
-!!! error TS2769:                     Type 'IteratorYieldResult<number>' is not assignable to type 'IteratorYieldResult<bigint>'.
-!!! error TS2769:                       Type 'number' is not assignable to type 'bigint'.
+!!! error TS2769:       The types of '[Symbol.iterator]().next(...)' are incompatible between these types.
+!!! error TS2769:         Type 'IteratorResult<number, any>' is not assignable to type 'IteratorResult<bigint, any>'.
+!!! error TS2769:           Type 'IteratorYieldResult<number>' is not assignable to type 'IteratorResult<bigint, any>'.
+!!! error TS2769:             Type 'IteratorYieldResult<number>' is not assignable to type 'IteratorYieldResult<bigint>'.
+!!! error TS2769:               Type 'number' is not assignable to type 'bigint'.
 !!! error TS2769:   Overload 3 of 3, '(buffer: ArrayBuffer | SharedArrayBuffer, byteOffset?: number, length?: number): BigInt64Array', gave the following error.
 !!! error TS2769:     Argument of type 'number[]' is not assignable to parameter of type 'ArrayBuffer | SharedArrayBuffer'.
 !!! error TS2769:       Type 'number[]' is missing the following properties from type 'SharedArrayBuffer': byteLength, [Symbol.species], [Symbol.toStringTag]

tests/baselines/reference/booleanAssignment.errors.txt

@@ -1,9 +1,8 @@
 tests/cases/compiler/booleanAssignment.ts(2,1): error TS2322: Type '1' is not assignable to type 'Boolean'.
 tests/cases/compiler/booleanAssignment.ts(3,1): error TS2322: Type '"a"' is not assignable to type 'Boolean'.
 tests/cases/compiler/booleanAssignment.ts(4,1): error TS2322: Type '{}' is not assignable to type 'Boolean'.
-  Types of property 'valueOf' are incompatible.
-    Type '() => Object' is not assignable to type '() => boolean'.
-      Type 'Object' is not assignable to type 'boolean'.
+  The types of 'valueOf()' are incompatible between these types.
+    Type 'Object' is not assignable to type 'boolean'.
 
 
 ==== tests/cases/compiler/booleanAssignment.ts (3 errors) ====
@@ -17,9 +16,8 @@ tests/cases/compiler/booleanAssignment.ts(4,1): error TS2322: Type '{}' is not a
     b = {}; // Error
     ~
 !!! error TS2322: Type '{}' is not assignable to type 'Boolean'.
-!!! error TS2322:   Types of property 'valueOf' are incompatible.
-!!! error TS2322:     Type '() => Object' is not assignable to type '() => boolean'.
-!!! error TS2322:       Type 'Object' is not assignable to type 'boolean'.
+!!! error TS2322:   The types of 'valueOf()' are incompatible between these types.
+!!! error TS2322:     Type 'Object' is not assignable to type 'boolean'.
 
     var o = {};
     o = b; // OK