microsoft · DanielRosenwasser · May 21, 2019 · May 21, 2019 · May 21, 2019
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
@@ -5352,7 +5352,7 @@ namespace ts {
                     return type;
                 }
                 else if (declaredType !== errorType && type !== errorType && !isTypeIdenticalTo(declaredType, type)) {
-                    errorNextVariableOrPropertyDeclarationMustHaveSameType(declaredType, declaration, type);
+                    errorNextVariableOrPropertyDeclarationMustHaveSameType(/*firstDeclaration*/ undefined, declaredType, declaration, type);
                 }
             }
             return declaredType;
@@ -26839,7 +26839,7 @@ namespace ts {
                 if (type !== errorType && declarationType !== errorType &&
                     !isTypeIdenticalTo(type, declarationType) &&
                     !(symbol.flags & SymbolFlags.Assignment)) {
-                    errorNextVariableOrPropertyDeclarationMustHaveSameType(type, node, declarationType);
+                    errorNextVariableOrPropertyDeclarationMustHaveSameType(symbol.valueDeclaration, type, node, declarationType);
                 }
                 if (node.initializer) {
                     checkTypeAssignableToAndOptionallyElaborate(checkExpressionCached(node.initializer), declarationType, node, node.initializer, /*headMessage*/ undefined);
@@ -26859,17 +26859,24 @@ namespace ts {
             }
         }
 
-        function errorNextVariableOrPropertyDeclarationMustHaveSameType(firstType: Type, nextDeclaration: Declaration, nextType: Type): void {
+        function errorNextVariableOrPropertyDeclarationMustHaveSameType(firstDeclaration: Declaration | undefined, firstType: Type, nextDeclaration: Declaration, nextType: Type): void {
             const nextDeclarationName = getNameOfDeclaration(nextDeclaration);
             const message = nextDeclaration.kind === SyntaxKind.PropertyDeclaration || nextDeclaration.kind === SyntaxKind.PropertySignature
                 ? Diagnostics.Subsequent_property_declarations_must_have_the_same_type_Property_0_must_be_of_type_1_but_here_has_type_2
                 : Diagnostics.Subsequent_variable_declarations_must_have_the_same_type_Variable_0_must_be_of_type_1_but_here_has_type_2;
-            error(
+            const declName = declarationNameToString(nextDeclarationName);
+            const err = error(
                 nextDeclarationName,
                 message,
-                declarationNameToString(nextDeclarationName),
+                declName,
                 typeToString(firstType),
-                typeToString(nextType));
+                typeToString(nextType)
+            );
+            if (firstDeclaration) {
+                addRelatedInfo(err,
+                    createDiagnosticForNode(firstDeclaration, Diagnostics._0_was_also_declared_here, declName)
+                );
+            }
         }
 
         function areDeclarationFlagsIdentical(left: Declaration, right: Declaration) {

diff --git a/tests/baselines/reference/ES5For-of7.errors.txt b/tests/baselines/reference/ES5For-of7.errors.txt
@@ -10,4 +10,5 @@ tests/cases/conformance/statements/for-ofStatements/ES5For-of7.ts(6,9): error TS
         var x = [w, v];
             ~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'x' must be of type 'any', but here has type 'any[]'.
+!!! related TS6203 tests/cases/conformance/statements/for-ofStatements/ES5For-of7.ts:2:9: 'x' was also declared here.
     }
diff --git a/tests/baselines/reference/FunctionAndModuleWithSameNameAndCommonRoot.errors.txt b/tests/baselines/reference/FunctionAndModuleWithSameNameAndCommonRoot.errors.txt
@@ -24,6 +24,7 @@ tests/cases/conformance/internalModules/DeclarationMerging/test.ts(2,5): error T
     var fn = A.Point;
         ~~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'fn' must be of type '() => { x: number; y: number; }', but here has type 'typeof Point'.
+!!! related TS6203 tests/cases/conformance/internalModules/DeclarationMerging/test.ts:1:5: 'fn' was also declared here.
 
     var cl: { x: number; y: number; }
     var cl = A.Point();
@@ -46,6 +47,7 @@ tests/cases/conformance/internalModules/DeclarationMerging/test.ts(2,5): error T
     var fn = B.Point;  // not expected to be an error. bug 840000: [corelang] Function of fundule not assignalbe as expected
         ~~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'fn' must be of type '() => { x: number; y: number; }', but here has type 'typeof Point'.
+!!! related TS6203 tests/cases/conformance/internalModules/DeclarationMerging/test.ts:1:5: 'fn' was also declared here.
 
     var cl: { x: number; y: number; }
     var cl = B.Point();

diff --git a/tests/baselines/reference/asyncArrowFunction5_es2017.errors.txt b/tests/baselines/reference/asyncArrowFunction5_es2017.errors.txt
@@ -16,6 +16,7 @@ tests/cases/conformance/async/es2017/asyncArrowFunction/asyncArrowFunction5_es20
 !!! error TS1005: ',' expected.
                              ~~~~~~~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'Promise' must be of type 'PromiseConstructor', but here has type 'any'.
+!!! related TS6203 /.ts/lib.es2015.promise.d.ts:152:13: 'Promise' was also declared here.
                                     ~
 !!! error TS1005: ',' expected.
                                            ~~

diff --git a/tests/baselines/reference/asyncArrowFunction5_es5.errors.txt b/tests/baselines/reference/asyncArrowFunction5_es5.errors.txt
@@ -16,6 +16,7 @@ tests/cases/conformance/async/es5/asyncArrowFunction/asyncArrowFunction5_es5.ts(
 !!! error TS1005: ',' expected.
                              ~~~~~~~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'Promise' must be of type 'PromiseConstructor', but here has type 'any'.
+!!! related TS6203 /.ts/lib.es2015.promise.d.ts:152:13: 'Promise' was also declared here.
                                     ~
 !!! error TS1005: ',' expected.
                                            ~~

diff --git a/tests/baselines/reference/asyncArrowFunction5_es6.errors.txt b/tests/baselines/reference/asyncArrowFunction5_es6.errors.txt
@@ -16,6 +16,7 @@ tests/cases/conformance/async/es6/asyncArrowFunction/asyncArrowFunction5_es6.ts(
 !!! error TS1005: ',' expected.
                              ~~~~~~~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'Promise' must be of type 'PromiseConstructor', but here has type 'any'.
+!!! related TS6203 /.ts/lib.es2015.promise.d.ts:152:13: 'Promise' was also declared here.
                                     ~
 !!! error TS1005: ',' expected.
                                            ~~

diff --git a/tests/baselines/reference/asyncArrowFunction9_es2017.errors.txt b/tests/baselines/reference/asyncArrowFunction9_es2017.errors.txt
@@ -16,6 +16,7 @@ tests/cases/conformance/async/es2017/asyncArrowFunction/asyncArrowFunction9_es20
 !!! error TS1005: ',' expected.
                                           ~~~~~~~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'Promise' must be of type 'PromiseConstructor', but here has type 'any'.
+!!! related TS6203 /.ts/lib.es2015.promise.d.ts:152:13: 'Promise' was also declared here.
                                                  ~
 !!! error TS1005: ',' expected.
                                                         ~~

diff --git a/tests/baselines/reference/asyncArrowFunction9_es5.errors.txt b/tests/baselines/reference/asyncArrowFunction9_es5.errors.txt
@@ -16,6 +16,7 @@ tests/cases/conformance/async/es5/asyncArrowFunction/asyncArrowFunction9_es5.ts(
 !!! error TS1005: ',' expected.
                                           ~~~~~~~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'Promise' must be of type 'PromiseConstructor', but here has type 'any'.
+!!! related TS6203 /.ts/lib.es2015.promise.d.ts:152:13: 'Promise' was also declared here.
                                                  ~
 !!! error TS1005: ',' expected.
                                                         ~~

diff --git a/tests/baselines/reference/asyncArrowFunction9_es6.errors.txt b/tests/baselines/reference/asyncArrowFunction9_es6.errors.txt
@@ -16,6 +16,7 @@ tests/cases/conformance/async/es6/asyncArrowFunction/asyncArrowFunction9_es6.ts(
 !!! error TS1005: ',' expected.
                                           ~~~~~~~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'Promise' must be of type 'PromiseConstructor', but here has type 'any'.
+!!! related TS6203 /.ts/lib.es2015.promise.d.ts:152:13: 'Promise' was also declared here.
                                                  ~
 !!! error TS1005: ',' expected.
                                                         ~~

diff --git a/tests/baselines/reference/augmentedTypesVar.errors.txt b/tests/baselines/reference/augmentedTypesVar.errors.txt
@@ -30,6 +30,7 @@ tests/cases/compiler/augmentedTypesVar.ts(31,8): error TS2300: Duplicate identif
     var x3 = () => { } // error
         ~~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'x3' must be of type 'number', but here has type '() => void'.
+!!! related TS6203 tests/cases/compiler/augmentedTypesVar.ts:9:5: 'x3' was also declared here.
 
     // var then class
     var x4 = 1; // error

diff --git a/tests/baselines/reference/castingTuple.errors.txt b/tests/baselines/reference/castingTuple.errors.txt
@@ -71,6 +71,7 @@ tests/cases/conformance/types/tuple/castingTuple.ts(33,1): error TS2304: Cannot
     var array1 = <number[]>numStrTuple;
         ~~~~~~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'array1' must be of type '{}[]', but here has type 'number[]'.
+!!! related TS6203 tests/cases/conformance/types/tuple/castingTuple.ts:23:5: 'array1' was also declared here.
     t4[2] = 10;
     ~~
 !!! error TS2304: Cannot find name 't4'.

diff --git a/tests/baselines/reference/checkMergedGlobalUMDSymbol.errors.txt b/tests/baselines/reference/checkMergedGlobalUMDSymbol.errors.txt
@@ -15,6 +15,7 @@ tests/cases/compiler/global.d.ts(6,16): error TS2403: Subsequent variable declar
       export const THREE: typeof _three;
                    ~~~~~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'THREE' must be of type 'typeof import("tests/cases/compiler/global")', but here has type 'typeof import("tests/cases/compiler/three")'.
+!!! related TS6203 tests/cases/compiler/global.d.ts:1:1: 'THREE' was also declared here.
     }
 
 ==== tests/cases/compiler/test.ts (0 errors) ====

diff --git a/tests/baselines/reference/classWithDuplicateIdentifier.errors.txt b/tests/baselines/reference/classWithDuplicateIdentifier.errors.txt
@@ -14,6 +14,7 @@ tests/cases/compiler/classWithDuplicateIdentifier.ts(11,5): error TS2717: Subseq
 !!! error TS2300: Duplicate identifier 'a'.
         ~
 !!! error TS2717: Subsequent property declarations must have the same type.  Property 'a' must be of type '() => number', but here has type 'number'.
+!!! related TS6203 tests/cases/compiler/classWithDuplicateIdentifier.ts:2:5: 'a' was also declared here.
     }
     class K {
         b: number; // error: duplicate identifier
@@ -30,5 +31,6 @@ tests/cases/compiler/classWithDuplicateIdentifier.ts(11,5): error TS2717: Subseq
 !!! error TS2300: Duplicate identifier 'c'.
         ~
 !!! error TS2717: Subsequent property declarations must have the same type.  Property 'c' must be of type 'number', but here has type 'string'.
+!!! related TS6203 tests/cases/compiler/classWithDuplicateIdentifier.ts:10:5: 'c' was also declared here.
     }
 
diff --git a/tests/baselines/reference/conditionalTypes1.errors.txt b/tests/baselines/reference/conditionalTypes1.errors.txt
@@ -391,6 +391,7 @@ tests/cases/conformance/types/conditional/conditionalTypes1.ts(288,43): error TS
         var z: T2;  // Error, T2 is distributive, T1 isn't
             ~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'z' must be of type 'T1', but here has type 'Foo<T & U>'.
+!!! related TS6203 tests/cases/conformance/types/conditional/conditionalTypes1.ts:262:9: 'z' was also declared here.
     }
 
     function f33<T, U>() {

diff --git a/tests/baselines/reference/declarationsAndAssignments.errors.txt b/tests/baselines/reference/declarationsAndAssignments.errors.txt
@@ -97,6 +97,7 @@ tests/cases/conformance/es6/destructuring/declarationsAndAssignments.ts(138,9):
         var y: string;
             ~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'y' must be of type 'string | number', but here has type 'string'.
+!!! related TS6203 tests/cases/conformance/es6/destructuring/declarationsAndAssignments.ts:56:17: 'y' was also declared here.
     }
 
     function f8() {

diff --git a/tests/baselines/reference/duplicateClassElements.errors.txt b/tests/baselines/reference/duplicateClassElements.errors.txt
@@ -97,6 +97,7 @@ tests/cases/compiler/duplicateClassElements.ts(41,12): error TS2300: Duplicate i
 !!! error TS2300: Duplicate identifier 'x2'.
                ~~
 !!! error TS2717: Subsequent property declarations must have the same type.  Property 'x2' must be of type 'number', but here has type 'any'.
+!!! related TS6203 tests/cases/compiler/duplicateClassElements.ts:29:9: 'x2' was also declared here.
 
         get z2() {
             ~~

diff --git a/tests/baselines/reference/duplicateIdentifierInCatchBlock.errors.txt b/tests/baselines/reference/duplicateIdentifierInCatchBlock.errors.txt
@@ -38,4 +38,5 @@ tests/cases/compiler/duplicateIdentifierInCatchBlock.ts(16,9): error TS2403: Sub
         var p: number; // error
             ~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'p' must be of type 'string', but here has type 'number'.
+!!! related TS6203 tests/cases/compiler/duplicateIdentifierInCatchBlock.ts:15:9: 'p' was also declared here.
     }
diff --git a/tests/baselines/reference/duplicateLocalVariable1.errors.txt b/tests/baselines/reference/duplicateLocalVariable1.errors.txt
@@ -201,6 +201,7 @@ tests/cases/compiler/duplicateLocalVariable1.ts(186,37): error TS2356: An arithm
                 for (var i = 0; i < 14; i++) {
                          ~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'i' must be of type 'string', but here has type 'number'.
+!!! related TS6203 tests/cases/compiler/duplicateLocalVariable1.ts:181:22: 'i' was also declared here.
                                 ~~~~~~
 !!! error TS2365: Operator '<' cannot be applied to types 'string' and 'number'.
                                         ~

diff --git a/tests/baselines/reference/duplicateLocalVariable2.errors.txt b/tests/baselines/reference/duplicateLocalVariable2.errors.txt
@@ -33,6 +33,7 @@ tests/cases/compiler/duplicateLocalVariable2.ts(27,37): error TS2356: An arithme
                 for (var i = 0; i < 14; i++) {
                          ~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'i' must be of type 'string', but here has type 'number'.
+!!! related TS6203 tests/cases/compiler/duplicateLocalVariable2.ts:22:22: 'i' was also declared here.
                                 ~~~~~~
 !!! error TS2365: Operator '<' cannot be applied to types 'string' and 'number'.
                                         ~

diff --git a/tests/baselines/reference/duplicateLocalVariable3.errors.txt b/tests/baselines/reference/duplicateLocalVariable3.errors.txt
@@ -15,4 +15,5 @@ tests/cases/compiler/duplicateLocalVariable3.ts(11,9): error TS2403: Subsequent
         var z = "";
             ~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'z' must be of type 'number', but here has type 'string'.
+!!! related TS6203 tests/cases/compiler/duplicateLocalVariable3.ts:10:9: 'z' was also declared here.
     }
diff --git a/tests/baselines/reference/duplicateLocalVariable4.errors.txt b/tests/baselines/reference/duplicateLocalVariable4.errors.txt
@@ -9,4 +9,5 @@ tests/cases/compiler/duplicateLocalVariable4.ts(6,5): error TS2403: Subsequent v
     var x = E;
     var x = E.a;
         ~
-!!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'x' must be of type 'typeof E', but here has type 'E'.
+!!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'x' must be of type 'typeof E', but here has type 'E'.
+!!! related TS6203 tests/cases/compiler/duplicateLocalVariable4.ts:5:5: 'x' was also declared here.
diff --git a/tests/baselines/reference/duplicateVariablesWithAny.errors.txt b/tests/baselines/reference/duplicateVariablesWithAny.errors.txt
@@ -10,22 +10,26 @@ tests/cases/compiler/duplicateVariablesWithAny.ts(13,9): error TS2403: Subsequen
     var x = 2; //error
         ~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'x' must be of type 'any', but here has type 'number'.
+!!! related TS6203 tests/cases/compiler/duplicateVariablesWithAny.ts:2:5: 'x' was also declared here.
 
     var y = "";
     var y; //error
         ~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'y' must be of type 'string', but here has type 'any'.
+!!! related TS6203 tests/cases/compiler/duplicateVariablesWithAny.ts:5:5: 'y' was also declared here.
 
     module N {
         var x: any;
         var x = 2; //error
             ~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'x' must be of type 'any', but here has type 'number'.
+!!! related TS6203 tests/cases/compiler/duplicateVariablesWithAny.ts:9:9: 'x' was also declared here.
 
         var y = "";
         var y; //error
             ~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'y' must be of type 'string', but here has type 'any'.
+!!! related TS6203 tests/cases/compiler/duplicateVariablesWithAny.ts:12:9: 'y' was also declared here.
     }
 
     var z: any;

diff --git a/tests/baselines/reference/duplicateVarsAcrossFileBoundaries.errors.txt b/tests/baselines/reference/duplicateVarsAcrossFileBoundaries.errors.txt
@@ -12,18 +12,22 @@ tests/cases/compiler/duplicateVarsAcrossFileBoundaries_2.ts(3,5): error TS2403:
     var x = true;
         ~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'x' must be of type 'number', but here has type 'boolean'.
+!!! related TS6203 tests/cases/compiler/duplicateVarsAcrossFileBoundaries_0.ts:1:5: 'x' was also declared here.
     var z = 3;
 
 ==== tests/cases/compiler/duplicateVarsAcrossFileBoundaries_2.ts (3 errors) ====
     var x = "";
         ~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'x' must be of type 'number', but here has type 'string'.
+!!! related TS6203 tests/cases/compiler/duplicateVarsAcrossFileBoundaries_0.ts:1:5: 'x' was also declared here.
     var y = 3;
         ~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'y' must be of type 'string', but here has type 'number'.
+!!! related TS6203 tests/cases/compiler/duplicateVarsAcrossFileBoundaries_0.ts:2:5: 'y' was also declared here.
     var z = false;
         ~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'z' must be of type 'number', but here has type 'boolean'.
+!!! related TS6203 tests/cases/compiler/duplicateVarsAcrossFileBoundaries_1.ts:2:5: 'z' was also declared here.
 
 ==== tests/cases/compiler/duplicateVarsAcrossFileBoundaries_3.ts (0 errors) ====
     var x = 0;

diff --git a/tests/baselines/reference/dynamicNamesErrors.errors.txt b/tests/baselines/reference/dynamicNamesErrors.errors.txt
@@ -35,6 +35,7 @@ tests/cases/compiler/dynamicNamesErrors.ts(25,1): error TS2322: Type 'T1' is not
         [c1]: string;
         ~~~~
 !!! error TS2717: Subsequent property declarations must have the same type.  Property '[c1]' must be of type 'number', but here has type 'string'.
+!!! related TS6203 tests/cases/compiler/dynamicNamesErrors.ts:18:5: '[c1]' was also declared here.
     }
 
     let t1: T1;

diff --git a/tests/baselines/reference/enumAssignabilityInInheritance.errors.txt b/tests/baselines/reference/enumAssignabilityInInheritance.errors.txt
@@ -109,10 +109,12 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/enumAssi
     var r4 = foo16(E.A);
         ~~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'r4' must be of type 'E', but here has type 'Object'.
+!!! related TS6203 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/enumAssignabilityInInheritance.ts:22:5: 'r4' was also declared here.
 
     declare function foo17(x: {}): {};
     declare function foo17(x: E): E;
 
     var r4 = foo16(E.A);
         ~~
-!!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'r4' must be of type 'E', but here has type 'Object'.
+!!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'r4' must be of type 'E', but here has type 'Object'.
+!!! related TS6203 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/enumAssignabilityInInheritance.ts:22:5: 'r4' was also declared here.
diff --git a/tests/baselines/reference/for-inStatements.errors.txt b/tests/baselines/reference/for-inStatements.errors.txt
@@ -39,6 +39,7 @@ tests/cases/conformance/statements/for-inStatements/for-inStatements.ts(79,15):
             for (var x in this) { }
                      ~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'x' must be of type 'string', but here has type 'Extract<keyof this, string>'.
+!!! related TS6203 tests/cases/conformance/statements/for-inStatements/for-inStatements.ts:31:18: 'x' was also declared here.
             return null;
         }
 
@@ -58,6 +59,7 @@ tests/cases/conformance/statements/for-inStatements/for-inStatements.ts(79,15):
             for (var x in this) { }
                      ~
 !!! error TS2403: Subsequent variable declarations must have the same type.  Variable 'x' must be of type 'string', but here has type 'Extract<keyof this, string>'.
+!!! related TS6203 tests/cases/conformance/statements/for-inStatements/for-inStatements.ts:48:18: 'x' was also declared here.
 
             for (var x in super.biz) { }
             for (var x in super.biz()) { }