maxmustermann/TypeScript
1
0
Fork 0
Code Issues Pull requests Projects Releases Wiki Activity

Use getTypeOfExpression when inferring variable type from initializer

Browse source
This commit is contained in:
Anders Hejlsberg 2017-03-03 14:32:18 -08:00
parent 0afb84a123
commit 65cea207da
1 changed files with 6 additions and 4 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

10
src/compiler/checker.ts
View file

@ -16131,7 +16131,7 @@ namespace ts {
}
function checkDeclarationInitializer(declaration: VariableLikeDeclaration) {
const type = checkExpressionCached(declaration.initializer);
const type = getTypeOfExpression(declaration.initializer, /*cache*/ true);
return getCombinedNodeFlags(declaration) & NodeFlags.Const ||
getCombinedModifierFlags(declaration) & ModifierFlags.Readonly && !isParameterPropertyDeclaration(declaration) ||
isTypeAssertion(declaration.initializer) ? type : getWidenedLiteralType(type);
@ -16204,10 +16204,12 @@ namespace ts {
// Returns the type of an expression. Unlike checkExpression, this function is simply concerned
// with computing the type and may not fully check all contained sub-expressions for errors.
function getTypeOfExpression(node: Expression) {
// A cache argument of true indicates that if the function performs a full type check, it is ok
// to cache the result.
function getTypeOfExpression(node: Expression, cache?: boolean) {
// 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) {
if (node.kind === SyntaxKind.CallExpression && (<CallExpression>node).expression.kind !== SyntaxKind.SuperKeyword && !isRequireCall(node, /*checkArgumentIsStringLiteral*/true)) {
const funcType = checkNonNullExpression((<CallExpression>node).expression);
const signature = getSingleCallSignature(funcType);
if (signature && !signature.typeParameters) {
@ -16217,7 +16219,7 @@ namespace ts {
// 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.
return checkExpression(node);
return cache ? checkExpressionCached(node) : checkExpression(node);
}
// Checks an expression and returns its type. The contextualMapper parameter serves two purposes: When