Allow functions and ambient classes to merge

src/compiler/checker.ts

@@ -26276,8 +26276,9 @@ namespace ts {
 
             let duplicateFunctionDeclaration = false;
             let multipleConstructorImplementation = false;
+            let hasNonAmbientClass = false;
             for (const current of declarations) {
-                const node = <SignatureDeclaration>current;
+                const node = <SignatureDeclaration | ClassDeclaration | ClassExpression>current;
                 const inAmbientContext = node.flags & NodeFlags.Ambient;
                 const inAmbientContextOrInterface = node.parent.kind === SyntaxKind.InterfaceDeclaration || node.parent.kind === SyntaxKind.TypeLiteral || inAmbientContext;
                 if (inAmbientContextOrInterface) {
@@ -26291,6 +26292,10 @@ namespace ts {
                     previousDeclaration = undefined;
                 }
 
+                if ((node.kind === SyntaxKind.ClassDeclaration || node.kind === SyntaxKind.ClassExpression) && !inAmbientContext) {
+                    hasNonAmbientClass = true;
+                }
+
                 if (node.kind === SyntaxKind.FunctionDeclaration || node.kind === SyntaxKind.MethodDeclaration || node.kind === SyntaxKind.MethodSignature || node.kind === SyntaxKind.Constructor) {
                     const currentNodeFlags = getEffectiveDeclarationFlags(node, flagsToCheck);
                     someNodeFlags |= currentNodeFlags;
@@ -26339,6 +26344,16 @@ namespace ts {
                 });
             }
 
+            if (hasNonAmbientClass && !isConstructor && symbol.flags & SymbolFlags.Function) {
+                // A non-ambient class cannot be an implementation for a non-constructor function/class merge
+                // TODO: The below just replicates our older error from when classes and functions were
+                // entirely unable to merge - a more helpful message like "Class declaration cannot implement overload list"
+                // might be warranted. :shrug:
+                forEach(declarations, declaration => {
+                    addDuplicateDeclarationError(getNameOfDeclaration(declaration) || declaration, Diagnostics.Duplicate_identifier_0, symbolName(symbol), filter(declarations, d => d !== declaration));
+                });
+            }
+
             // Abstract methods can't have an implementation -- in particular, they don't need one.
             if (lastSeenNonAmbientDeclaration && !lastSeenNonAmbientDeclaration.body &&
                 !hasModifier(lastSeenNonAmbientDeclaration, ModifierFlags.Abstract) && !lastSeenNonAmbientDeclaration.questionToken) {
@@ -31650,7 +31665,7 @@ namespace ts {
             if (!symbol || !(symbol.flags & SymbolFlags.Function)) {
                 return false;
             }
-            return !!forEachEntry(getExportsOfSymbol(symbol), p => p.flags & SymbolFlags.Value && isPropertyAccessExpression(p.valueDeclaration));
+            return !!forEachEntry(getExportsOfSymbol(symbol), p => p.flags & SymbolFlags.Value && p.valueDeclaration && isPropertyAccessExpression(p.valueDeclaration));
         }
 
         function getPropertiesOfContainerFunction(node: Declaration): Symbol[] {

src/compiler/types.ts

@@ -3678,8 +3678,8 @@ namespace ts {
         ParameterExcludes = Value,
         PropertyExcludes = None,
         EnumMemberExcludes = Value | Type,
-        FunctionExcludes = Value & ~(Function | ValueModule),
-        ClassExcludes = (Value | Type) & ~(ValueModule | Interface), // class-interface mergability done in checker.ts
+        FunctionExcludes = Value & ~(Function | ValueModule | Class),
+        ClassExcludes = (Value | Type) & ~(ValueModule | Interface | Function), // class-interface mergability done in checker.ts
         InterfaceExcludes = Type & ~(Interface | Class),
         RegularEnumExcludes = (Value | Type) & ~(RegularEnum | ValueModule), // regular enums merge only with regular enums and modules
         ConstEnumExcludes = (Value | Type) & ~ConstEnum, // const enums merge only with const enums

tests/baselines/reference/ambientClassOverloadForFunction.symbols

@@ -1,7 +1,7 @@
 === tests/cases/compiler/ambientClassOverloadForFunction.ts ===
 declare class foo{};
->foo : Symbol(foo, Decl(ambientClassOverloadForFunction.ts, 0, 0))
+>foo : Symbol(foo, Decl(ambientClassOverloadForFunction.ts, 0, 20), Decl(ambientClassOverloadForFunction.ts, 0, 0))
 
 function foo() { return null; }
->foo : Symbol(foo, Decl(ambientClassOverloadForFunction.ts, 0, 20))
+>foo : Symbol(foo, Decl(ambientClassOverloadForFunction.ts, 0, 20), Decl(ambientClassOverloadForFunction.ts, 0, 0))
 

tests/baselines/reference/ambientClassOverloadForFunction.types

@@ -3,6 +3,6 @@ declare class foo{};
 >foo : foo
 
 function foo() { return null; }
->foo : () => any
+>foo : typeof foo
 >null : null
 

tests/baselines/reference/api/tsserverlibrary.d.ts

@@ -2137,8 +2137,8 @@ declare namespace ts {
         ParameterExcludes = 111551,
         PropertyExcludes = 0,
         EnumMemberExcludes = 900095,
-        FunctionExcludes = 111023,
-        ClassExcludes = 899519,
+        FunctionExcludes = 110991,
+        ClassExcludes = 899503,
         InterfaceExcludes = 788872,
         RegularEnumExcludes = 899327,
         ConstEnumExcludes = 899967,

tests/baselines/reference/api/typescript.d.ts

@@ -2137,8 +2137,8 @@ declare namespace ts {
         ParameterExcludes = 111551,
         PropertyExcludes = 0,
         EnumMemberExcludes = 900095,
-        FunctionExcludes = 111023,
-        ClassExcludes = 899519,
+        FunctionExcludes = 110991,
+        ClassExcludes = 899503,
         InterfaceExcludes = 788872,
         RegularEnumExcludes = 899327,
         ConstEnumExcludes = 899967,

tests/baselines/reference/augmentedTypesClass2a.errors.txt

@@ -1,15 +1,23 @@
 tests/cases/compiler/augmentedTypesClass2a.ts(2,7): error TS2300: Duplicate identifier 'c2'.
+tests/cases/compiler/augmentedTypesClass2a.ts(2,7): error TS2300: Duplicate identifier 'c2'.
+tests/cases/compiler/augmentedTypesClass2a.ts(3,10): error TS2300: Duplicate identifier 'c2'.
 tests/cases/compiler/augmentedTypesClass2a.ts(3,10): error TS2300: Duplicate identifier 'c2'.
 tests/cases/compiler/augmentedTypesClass2a.ts(4,5): error TS2300: Duplicate identifier 'c2'.
 
 
-==== tests/cases/compiler/augmentedTypesClass2a.ts (3 errors) ====
+==== tests/cases/compiler/augmentedTypesClass2a.ts (5 errors) ====
     //// class then function
     class c2 { public foo() { } } // error
           ~~
+!!! error TS2300: Duplicate identifier 'c2'.
+!!! related TS6203 tests/cases/compiler/augmentedTypesClass2a.ts:3:10: 'c2' was also declared here.
+          ~~
 !!! error TS2300: Duplicate identifier 'c2'.
     function c2() { } // error
              ~~
+!!! error TS2300: Duplicate identifier 'c2'.
+!!! related TS6203 tests/cases/compiler/augmentedTypesClass2a.ts:2:7: 'c2' was also declared here.
+             ~~
 !!! error TS2300: Duplicate identifier 'c2'.
     var c2 = () => { }
         ~~

tests/baselines/reference/augmentedTypesClass2a.symbols

@@ -1,11 +1,11 @@
 === tests/cases/compiler/augmentedTypesClass2a.ts ===
 //// class then function
 class c2 { public foo() { } } // error
->c2 : Symbol(c2, Decl(augmentedTypesClass2a.ts, 0, 0))
+>c2 : Symbol(c2, Decl(augmentedTypesClass2a.ts, 1, 29), Decl(augmentedTypesClass2a.ts, 0, 0))
 >foo : Symbol(c2.foo, Decl(augmentedTypesClass2a.ts, 1, 10))
 
 function c2() { } // error
->c2 : Symbol(c2, Decl(augmentedTypesClass2a.ts, 1, 29))
+>c2 : Symbol(c2, Decl(augmentedTypesClass2a.ts, 1, 29), Decl(augmentedTypesClass2a.ts, 0, 0))
 
 var c2 = () => { }
 >c2 : Symbol(c2, Decl(augmentedTypesClass2a.ts, 3, 3))

tests/baselines/reference/augmentedTypesClass2a.types

@@ -5,7 +5,7 @@ class c2 { public foo() { } } // error
 >foo : () => void
 
 function c2() { } // error
->c2 : () => void
+>c2 : typeof c2
 
 var c2 = () => { }
 >c2 : () => void

tests/baselines/reference/augmentedTypesFunction.errors.txt

@@ -40,16 +40,20 @@ tests/cases/compiler/augmentedTypesFunction.ts(21,6): error TS2567: Enum declara
     function y3() { } // error
              ~~
 !!! error TS2300: Duplicate identifier 'y3'.
+!!! related TS6203 tests/cases/compiler/augmentedTypesFunction.ts:14:7: 'y3' was also declared here.
     class y3 { } // error
           ~~
 !!! error TS2300: Duplicate identifier 'y3'.
+!!! related TS6203 tests/cases/compiler/augmentedTypesFunction.ts:13:10: 'y3' was also declared here.
 
     function y3a() { } // error
              ~~~
 !!! error TS2300: Duplicate identifier 'y3a'.
+!!! related TS6203 tests/cases/compiler/augmentedTypesFunction.ts:17:7: 'y3a' was also declared here.
     class y3a { public foo() { } } // error
           ~~~
 !!! error TS2300: Duplicate identifier 'y3a'.
+!!! related TS6203 tests/cases/compiler/augmentedTypesFunction.ts:16:10: 'y3a' was also declared here.
 
     // function then enum
     function y4() { } // error

tests/baselines/reference/augmentedTypesFunction.symbols

@@ -21,16 +21,16 @@ var y2a = () => { } // error
 
 // function then class
 function y3() { } // error
->y3 : Symbol(y3, Decl(augmentedTypesFunction.ts, 9, 19))
+>y3 : Symbol(y3, Decl(augmentedTypesFunction.ts, 9, 19), Decl(augmentedTypesFunction.ts, 12, 17))
 
 class y3 { } // error
->y3 : Symbol(y3, Decl(augmentedTypesFunction.ts, 12, 17))
+>y3 : Symbol(y3, Decl(augmentedTypesFunction.ts, 9, 19), Decl(augmentedTypesFunction.ts, 12, 17))
 
 function y3a() { } // error
->y3a : Symbol(y3a, Decl(augmentedTypesFunction.ts, 13, 12))
+>y3a : Symbol(y3a, Decl(augmentedTypesFunction.ts, 13, 12), Decl(augmentedTypesFunction.ts, 15, 18))
 
 class y3a { public foo() { } } // error
->y3a : Symbol(y3a, Decl(augmentedTypesFunction.ts, 15, 18))
+>y3a : Symbol(y3a, Decl(augmentedTypesFunction.ts, 13, 12), Decl(augmentedTypesFunction.ts, 15, 18))
 >foo : Symbol(y3a.foo, Decl(augmentedTypesFunction.ts, 16, 11))
 
 // function then enum

tests/baselines/reference/augmentedTypesFunction.types

@@ -23,13 +23,13 @@ var y2a = () => { } // error
 
 // function then class
 function y3() { } // error
->y3 : () => void
+>y3 : typeof y3
 
 class y3 { } // error
 >y3 : y3
 
 function y3a() { } // error
->y3a : () => void
+>y3a : typeof y3a
 
 class y3a { public foo() { } } // error
 >y3a : y3a

tests/baselines/reference/callOnInstance.errors.txt

@@ -1,24 +1,20 @@
-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(7,18): error TS2349: This expression is not callable.
+  Type 'D' has no 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) ====
+==== tests/cases/compiler/callOnInstance.ts (2 errors) ====
     declare function D(): string; // error
-                     ~
-!!! error TS2300: Duplicate identifier 'D'.
 
     declare class D { constructor (value: number); } // error
-                  ~
-!!! error TS2300: Duplicate identifier 'D'.
 
     var s1: string = D(); // OK
 
     var s2: string = (new D(1))();
-                            ~
-!!! error TS2554: Expected 0 arguments, but got 1.
+                     ~~~~~~~~~~
+!!! error TS2349: This expression is not callable.
+!!! error TS2349:   Type 'D' has no call signatures.
 
     declare class C { constructor(value: number); }
     (new C(1))(); // Error for calling an instance

tests/baselines/reference/callOnInstance.symbols

@@ -1,18 +1,18 @@
 === tests/cases/compiler/callOnInstance.ts ===
 declare function D(): string; // error
->D : Symbol(D, Decl(callOnInstance.ts, 0, 0))
+>D : Symbol(D, Decl(callOnInstance.ts, 0, 0), Decl(callOnInstance.ts, 0, 29))
 
 declare class D { constructor (value: number); } // error
->D : Symbol(D, Decl(callOnInstance.ts, 0, 29))
+>D : Symbol(D, Decl(callOnInstance.ts, 0, 0), Decl(callOnInstance.ts, 0, 29))
 >value : Symbol(value, Decl(callOnInstance.ts, 2, 31))
 
 var s1: string = D(); // OK
 >s1 : Symbol(s1, Decl(callOnInstance.ts, 4, 3))
->D : Symbol(D, Decl(callOnInstance.ts, 0, 0))
+>D : Symbol(D, Decl(callOnInstance.ts, 0, 0), Decl(callOnInstance.ts, 0, 29))
 
 var s2: string = (new D(1))();
 >s2 : Symbol(s2, Decl(callOnInstance.ts, 6, 3))
->D : Symbol(D, Decl(callOnInstance.ts, 0, 0))
+>D : Symbol(D, Decl(callOnInstance.ts, 0, 0), Decl(callOnInstance.ts, 0, 29))
 
 declare class C { constructor(value: number); }
 >C : Symbol(C, Decl(callOnInstance.ts, 6, 30))

tests/baselines/reference/callOnInstance.types

@@ -1,6 +1,6 @@
 === tests/cases/compiler/callOnInstance.ts ===
 declare function D(): string; // error
->D : () => string
+>D : typeof D
 
 declare class D { constructor (value: number); } // error
 >D : D
@@ -9,14 +9,14 @@ declare class D { constructor (value: number); } // error
 var s1: string = D(); // OK
 >s1 : string
 >D() : string
->D : () => string
+>D : typeof D
 
 var s2: string = (new D(1))();
 >s2 : string
 >(new D(1))() : any
->(new D(1)) : any
->new D(1) : any
->D : () => string
+>(new D(1)) : D
+>new D(1) : D
+>D : typeof D
 >1 : 1
 
 declare class C { constructor(value: number); }

tests/baselines/reference/callOverloads1.errors.txt

@@ -1,13 +1,13 @@
 tests/cases/compiler/callOverloads1.ts(1,7): error TS2300: Duplicate identifier 'Foo'.
 tests/cases/compiler/callOverloads1.ts(9,10): error TS2300: Duplicate identifier 'Foo'.
 tests/cases/compiler/callOverloads1.ts(9,10): error TS2391: Function implementation is missing or not immediately following the declaration.
-tests/cases/compiler/callOverloads1.ts(13,18): error TS2554: Expected 0 arguments, but got 1.
 
 
-==== tests/cases/compiler/callOverloads1.ts (4 errors) ====
+==== tests/cases/compiler/callOverloads1.ts (3 errors) ====
     class Foo { // error
           ~~~
 !!! error TS2300: Duplicate identifier 'Foo'.
+!!! related TS6203 tests/cases/compiler/callOverloads1.ts:9:10: 'Foo' was also declared here.
         bar1() { /*WScript.Echo("bar1");*/ }
 
         constructor(x: any) {
@@ -18,14 +18,13 @@ tests/cases/compiler/callOverloads1.ts(13,18): error TS2554: Expected 0 argument
     function Foo(); // error
              ~~~
 !!! error TS2300: Duplicate identifier 'Foo'.
+!!! related TS6203 tests/cases/compiler/callOverloads1.ts:1:7: 'Foo' was also declared here.
              ~~~
 !!! error TS2391: Function implementation is missing or not immediately following the declaration.
     function F1(s:string);
     function F1(a:any) { return a;}
 
     var f1 = new Foo("hey");
-                     ~~~~~
-!!! error TS2554: Expected 0 arguments, but got 1.
 
 
     f1.bar1();

tests/baselines/reference/callOverloads1.symbols

@@ -1,6 +1,6 @@
 === tests/cases/compiler/callOverloads1.ts ===
 class Foo { // error
->Foo : Symbol(Foo, Decl(callOverloads1.ts, 0, 0))
+>Foo : Symbol(Foo, Decl(callOverloads1.ts, 6, 1), Decl(callOverloads1.ts, 0, 0))
 
     bar1() { /*WScript.Echo("bar1");*/ }
 >bar1 : Symbol(Foo.bar1, Decl(callOverloads1.ts, 0, 11))
@@ -13,7 +13,7 @@ class Foo { // error
 }
 
 function Foo(); // error
->Foo : Symbol(Foo, Decl(callOverloads1.ts, 6, 1))
+>Foo : Symbol(Foo, Decl(callOverloads1.ts, 6, 1), Decl(callOverloads1.ts, 0, 0))
 
 function F1(s:string);
 >F1 : Symbol(F1, Decl(callOverloads1.ts, 8, 15), Decl(callOverloads1.ts, 9, 22))
@@ -26,12 +26,14 @@ function F1(a:any) { return a;}
 
 var f1 = new Foo("hey");
 >f1 : Symbol(f1, Decl(callOverloads1.ts, 12, 3))
->Foo : Symbol(Foo, Decl(callOverloads1.ts, 6, 1))
+>Foo : Symbol(Foo, Decl(callOverloads1.ts, 6, 1), Decl(callOverloads1.ts, 0, 0))
 
 
 f1.bar1();
+>f1.bar1 : Symbol(Foo.bar1, Decl(callOverloads1.ts, 0, 11))
 >f1 : Symbol(f1, Decl(callOverloads1.ts, 12, 3))
+>bar1 : Symbol(Foo.bar1, Decl(callOverloads1.ts, 0, 11))
 
 Foo();
->Foo : Symbol(Foo, Decl(callOverloads1.ts, 6, 1))
+>Foo : Symbol(Foo, Decl(callOverloads1.ts, 6, 1), Decl(callOverloads1.ts, 0, 0))