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Merge pull request #26679 from Microsoft/improveGetTypeOfExpression

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Improve control flow analysis of type assertions
This commit is contained in:
Anders Hejlsberg
2018-08-27 18:30:16 -07:00
committed by GitHub
parent bd40583beb a1c373c3c7
commit ac0d5da631
6 changed files with 173 additions and 5 deletions
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8
src/compiler/checker.ts
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@@ -21699,15 +21699,19 @@ namespace ts {
* to cache the result.
*/
function getTypeOfExpression(node: Expression, cache?: boolean) {
const expr = skipParentheses(node);
// Optimize for the common case of a call to a function with a single non-generic call
// signature where we can just fetch the return type without checking the arguments.
if (node.kind === SyntaxKind.CallExpression && (<CallExpression>node).expression.kind !== SyntaxKind.SuperKeyword && !isRequireCall(node, /*checkArgumentIsStringLiteralLike*/ true) && !isSymbolOrSymbolForCall(node)) {
const funcType = checkNonNullExpression((<CallExpression>node).expression);
if (expr.kind === SyntaxKind.CallExpression && (<CallExpression>expr).expression.kind !== SyntaxKind.SuperKeyword && !isRequireCall(expr, /*checkArgumentIsStringLiteralLike*/ true) && !isSymbolOrSymbolForCall(expr)) {
const funcType = checkNonNullExpression((<CallExpression>expr).expression);
const signature = getSingleCallSignature(funcType);
if (signature && !signature.typeParameters) {
return getReturnTypeOfSignature(signature);
}
}
else if (expr.kind === SyntaxKind.TypeAssertionExpression || expr.kind === SyntaxKind.AsExpression) {
return getTypeFromTypeNode((<TypeAssertion>expr).type);
}
// Otherwise simply call checkExpression. Ideally, the entire family of checkXXX functions
// should have a parameter that indicates whether full error checking is required such that
// we can perform the optimizations locally.