Allow to use a const in the initializer of a const enum #18887
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ghost
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file1.ts import { b } from './file2';
export const enum X {
a = 1,
c = b
}file2.ts export const b = 10;In your branch this compiles cleanly under |
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From discussion with @RyanCavanaugh: It looks like |
| @@ -36,9 +38,13 @@ tests/cases/compiler/constEnumErrors.ts(42,9): error TS2478: 'const' enum member | |||
| Y = E1.Z, | |||
| ~~~~ | |||
| !!! error TS2474: In 'const' enum declarations member initializer must be constant expression. | |||
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it would be nice to have this error go away and see only the new one.
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Is it good enough to have the new error message?
src/compiler/checker.ts
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| @@ -21898,6 +21908,13 @@ namespace ts { | |||
| } | |||
| return undefined; | |||
| } | |||
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| function getFromLiteralType(expr: Identifier | ElementAccessExpression | PropertyAccessExpression): string | number | undefined { | |||
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getTypeFromLiteral[Type]Node? The current name doesn't mean anything to me at all.
| case SyntaxKind.ElementAccessExpression: | ||
| case SyntaxKind.PropertyAccessExpression: | ||
| const ex = <PropertyAccessExpression | ElementAccessExpression>expr; | ||
| if (isConstantMemberAccess(ex)) { | ||
| const type = getTypeOfExpression(ex.expression); | ||
| const type = checkExpression(ex.expression); |
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why can't we use getTypeOfExpression anymore?
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We can, but it just has special handling for CallExpression that we don't need, then calls checkExpression.
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oh, that makes sense. I thought getTypeOfExpression was the fast path that was called by checkExpression, but I guess it actually just has some initial fast-path checks before delegating to checkExpression.
| const enum E { | ||
| y = x, | ||
| ~ | ||
| !!! error TS2474: In 'const' enum declarations member initializer must be constant expression. |
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could do with a better error message here too; x is const, but circular.
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This only works for constants with literal types? Otherwise there's no way the value can be inlined. |
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@ahejlsberg Good to go? |
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@ahejlsberg bump |
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@andy-ms can you talk to @ahejlsberg about this change |
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Thanks for your contribution. This PR has not been updated in a while and cannot be automatically merged at the time being. For housekeeping purposes we are closing stale PRs. If you'd still like to continue working on this PR, please leave a message and one of the maintainers can reopen it. |
Was there any reason we didn't do this already? It doesn't seem to cause errors in the presence of circularity.