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Control flow for element access expressions (#31478)

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* Control flow for element access expressions

Draft version, just want to see how performance is

* Add baselines

* Fix cast lint

* Cleanup to share code path

* Fix errant diffs
This commit is contained in:
Nathan Shively-Sanders
2019-07-16 10:10:58 -07:00
committed by GitHub
parent c7b8b2ae9b
commit 1de76cd605
5 changed files with 147 additions and 4 deletions
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13
src/compiler/checker.ts
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@@ -20573,10 +20573,15 @@ namespace ts {
}
propType = getConstraintForLocation(getTypeOfSymbol(prop), node);
}
return getFlowTypeOfAccessExpression(node, prop, propType, right);
}
function getFlowTypeOfAccessExpression(node: ElementAccessExpression | PropertyAccessExpression | QualifiedName, prop: Symbol | undefined, propType: Type, errorNode: Node) {
// Only compute control flow type if this is a property access expression that isn't an
// assignment target, and the referenced property was declared as a variable, property,
// accessor, or optional method.
if (node.kind !== SyntaxKind.PropertyAccessExpression ||
const assignmentKind = getAssignmentTargetKind(node);
if (node.kind !== SyntaxKind.ElementAccessExpression && node.kind !== SyntaxKind.PropertyAccessExpression ||
assignmentKind === AssignmentKind.Definite ||
prop && !(prop.flags & (SymbolFlags.Variable | SymbolFlags.Property | SymbolFlags.Accessor)) && !(prop.flags & SymbolFlags.Method && propType.flags & TypeFlags.Union)) {
return propType;
@@ -20586,7 +20591,7 @@ namespace ts {
// and if we are in a constructor of the same class as the property declaration, assume that
// the property is uninitialized at the top of the control flow.
let assumeUninitialized = false;
if (strictNullChecks && strictPropertyInitialization && left.kind === SyntaxKind.ThisKeyword) {
if (strictNullChecks && strictPropertyInitialization && node.expression.kind === SyntaxKind.ThisKeyword) {
const declaration = prop && prop.valueDeclaration;
if (declaration && isInstancePropertyWithoutInitializer(declaration)) {
const flowContainer = getControlFlowContainer(node);
@@ -20603,7 +20608,7 @@ namespace ts {
}
const flowType = getFlowTypeOfReference(node, propType, assumeUninitialized ? getOptionalType(propType) : propType);
if (assumeUninitialized && !(getFalsyFlags(propType) & TypeFlags.Undefined) && getFalsyFlags(flowType) & TypeFlags.Undefined) {
error(right, Diagnostics.Property_0_is_used_before_being_assigned, symbolToString(prop!)); // TODO: GH#18217
error(errorNode, Diagnostics.Property_0_is_used_before_being_assigned, symbolToString(prop!)); // TODO: GH#18217
// Return the declared type to reduce follow-on errors
return propType;
}
@@ -20960,7 +20965,7 @@ namespace ts {
AccessFlags.Writing | (isGenericObjectType(objectType) && !isThisTypeParameter(objectType) ? AccessFlags.NoIndexSignatures : 0) :
AccessFlags.None;
const indexedAccessType = getIndexedAccessTypeOrUndefined(objectType, effectiveIndexType, node, accessFlags) || errorType;
return checkIndexedAccessIndexType(indexedAccessType, node);
return checkIndexedAccessIndexType(getFlowTypeOfAccessExpression(node, indexedAccessType.symbol, indexedAccessType, indexExpression), node);
}
function checkThatExpressionIsProperSymbolReference(expression: Expression, expressionType: Type, reportError: boolean): boolean {