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Added new diagnostics message to clarify error for type guards #7348

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Merged
merged 1 commit into from
Mar 2, 2016
Merged

Added new diagnostics message to clarify error for type guards #7348

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5 changes: 4 additions & 1 deletion src/compiler/checker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -11815,9 +11815,12 @@ namespace ts {
Diagnostics.A_type_predicate_cannot_reference_a_rest_parameter);
}
else {
const leadingError = chainDiagnosticMessages(undefined, Diagnostics.A_type_predicate_s_type_must_be_assignable_to_its_parameter_s_type);
checkTypeAssignableTo(typePredicate.type,
getTypeOfNode(parent.parameters[typePredicate.parameterIndex]),
node.type);
node.type,
/*headMessage*/ undefined,
leadingError);
}
}
else if (parameterName) {
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4 changes: 4 additions & 0 deletions src/compiler/diagnosticMessages.json
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Expand Up @@ -1847,6 +1847,10 @@
"category": "Error",
"code": 2676
},
"A type predicate's type must be assignable to its parameter's type.": {
"category": "Error",
"code": 2677
},
"Import declaration '{0}' is using private name '{1}'.": {
"category": "Error",
"code": 4000
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22 changes: 14 additions & 8 deletions tests/baselines/reference/typeGuardFunctionErrors.errors.txt
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Expand Up @@ -12,10 +12,13 @@ tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(31,5):
tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(31,5): error TS7027: Unreachable code detected.
tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(32,1): error TS1128: Declaration or statement expected.
tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(34,38): error TS1225: Cannot find parameter 'x'.
tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(38,51): error TS2322: Type 'B' is not assignable to type 'A'.
Property 'propA' is missing in type 'B'.
tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(42,56): error TS2322: Type 'number' is not assignable to type 'string'.
tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(46,56): error TS2322: Type 'T[]' is not assignable to type 'string'.
tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(38,51): error TS2677: A type predicate's type must be assignable to its parameter's type.
Type 'B' is not assignable to type 'A'.
Property 'propA' is missing in type 'B'.
tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(42,56): error TS2677: A type predicate's type must be assignable to its parameter's type.
Type 'number' is not assignable to type 'string'.
tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(46,56): error TS2677: A type predicate's type must be assignable to its parameter's type.
Type 'T[]' is not assignable to type 'string'.
tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(60,7): error TS2339: Property 'propB' does not exist on type 'A'.
tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(65,7): error TS2339: Property 'propB' does not exist on type 'A'.
tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(70,7): error TS2339: Property 'propB' does not exist on type 'A'.
Expand Down Expand Up @@ -129,20 +132,23 @@ tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(137,39

function hasNonMatchingParameterType1(x: A): x is B {
~
!!! error TS2322: Type 'B' is not assignable to type 'A'.
!!! error TS2322: Property 'propA' is missing in type 'B'.
!!! error TS2677: A type predicate's type must be assignable to its parameter's type.
!!! error TS2677: Type 'B' is not assignable to type 'A'.
!!! error TS2677: Property 'propA' is missing in type 'B'.
return true;
}

function hasNonMatchingParameterType2(x: string): x is number {
~~~~~~
!!! error TS2322: Type 'number' is not assignable to type 'string'.
!!! error TS2677: A type predicate's type must be assignable to its parameter's type.
!!! error TS2677: Type 'number' is not assignable to type 'string'.
return true;
}

function hasNonMathcingGenericType<T>(a: string): a is T[] {
~~~
!!! error TS2322: Type 'T[]' is not assignable to type 'string'.
!!! error TS2677: A type predicate's type must be assignable to its parameter's type.
!!! error TS2677: Type 'T[]' is not assignable to type 'string'.
return true;
}

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