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Stop extracting void and never constants #18929

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Merged
merged 1 commit into from
Oct 4, 2017
Merged

Stop extracting void and never constants #18929

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12 changes: 12 additions & 0 deletions src/harness/unittests/extractConstants.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -222,9 +222,21 @@ const f = () => {

testExtractConstant("extractConstant_ArrowFunction_Expression",
`const f = () => [#|2 + 1|];`);

testExtractConstantFailed("extractConstant_Void", `
function f(): void { }
[#|f();|]`);

testExtractConstantFailed("extractConstant_Never", `
function f(): never { }
[#|f();|]`);
});

function testExtractConstant(caption: string, text: string) {
testExtractSymbol(caption, text, "extractConstant", Diagnostics.Extract_constant);
}

function testExtractConstantFailed(caption: string, text: string) {
testExtractSymbolFailed(caption, text, Diagnostics.Extract_constant);
}
}
19 changes: 16 additions & 3 deletions src/services/refactors/extractSymbol.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -127,6 +127,7 @@ namespace ts.refactor.extractSymbol {
export const CannotExtractSuper: DiagnosticMessage = createMessage("Cannot extract super call.");
export const CannotExtractEmpty: DiagnosticMessage = createMessage("Cannot extract empty range.");
export const ExpressionExpected: DiagnosticMessage = createMessage("expression expected.");
export const UselessConstantType: DiagnosticMessage = createMessage("No reason to extract constant of type.");
export const StatementOrExpressionExpected: DiagnosticMessage = createMessage("Statement or expression expected.");
export const CannotExtractRangeContainingConditionalBreakOrContinueStatements: DiagnosticMessage = createMessage("Cannot extract range containing conditional break or continue statements.");
export const CannotExtractRangeContainingConditionalReturnStatement: DiagnosticMessage = createMessage("Cannot extract range containing conditional return statement.");
Expand Down Expand Up @@ -1278,11 +1279,23 @@ namespace ts.refactor.extractSymbol {
const constantErrorsPerScope: Diagnostic[][] = [];
const visibleDeclarationsInExtractedRange: Symbol[] = [];

const expressionDiagnostic =
isReadonlyArray(targetRange.range) && !(targetRange.range.length === 1 && isExpressionStatement(targetRange.range[0]))
? ((start, end) => createFileDiagnostic(sourceFile, start, end - start, Messages.ExpressionExpected))(first(targetRange.range).getStart(), last(targetRange.range).end)
const expression = !isReadonlyArray(targetRange.range)
? targetRange.range
: targetRange.range.length === 1 && isExpressionStatement(targetRange.range[0])
? (targetRange.range[0] as ExpressionStatement).expression
: undefined;

let expressionDiagnostic: Diagnostic | undefined = undefined;
if (expression === undefined) {
const statements = targetRange.range as ReadonlyArray<Statement>;
const start = first(statements).getStart();
const end = last(statements).end;
expressionDiagnostic = createFileDiagnostic(sourceFile, start, end - start, Messages.ExpressionExpected);
}
else if (checker.getTypeAtLocation(expression).flags & (TypeFlags.Void | TypeFlags.Never)) {
expressionDiagnostic = createDiagnosticForNode(expression, Messages.UselessConstantType);
}

// initialize results
for (const scope of scopes) {
usagesPerScope.push({ usages: createMap<UsageEntry>(), typeParameterUsages: createMap<TypeParameter>(), substitutions: createMap<() => Expression>() });
Expand Down