consistently check expressions with >, >=, <, <= for unconstrained types in strictNullChecks #59352
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Hey @iisaduan, I've packed this into an installable tgz. You can install it for testing by referencing it in your and then running There is also a playground for this build and an npm module you can use via |
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Hey @iisaduan, the results of running the DT tests are ready. Everything looks the same! |
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@iisaduan Here are the results of running the user tests with tsc comparing Everything looks good! |
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@iisaduan Here they are:
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@iisaduan Here are the results of running the top 400 repos with tsc comparing Something interesting changed - please have a look. Details
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iisaduan
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iisaduan
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tests/baselines/reference/unconstrainedTypeComparison.errors.txt
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gabritto
reviewed
Jul 19, 2024
src/compiler/checker.ts
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| @@ -27493,6 +27493,11 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker { | |||
| return type === unknownUnionType ? unknownType : type; | |||
| } | |||
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| // use to determine if a parameter may be undefined or null (or is unknown/unconstrained) | |||
| function getUnknownIfMaybeUnknown(type: Type) { | |||
| return (strictNullChecks && type.flags & TypeFlags.Instantiable) ? getBaseConstraintOfType(type) || unknownType : type; | |||
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I'm assuming from #59059 that making this change to getTypeFacts breaks a lot of existing code, is that right?
Also, does making this change to checkNonNullType instead also break a lot of code?
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Yes, I tried that and putting this change directly into checkNonNullType gets a very similar result to #59059 in terms of breaking object index checking
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A lot of the cases that break relate to this type of index access #59059 (comment)
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I don't know if this it's noticeably different in semantics, but istead of doing this, you might want to try to modify getBaseTypeOfLiteralTypeForComparison and rename it getBaseTypeForComparison. Then pass the result of that into checkNonNullType.
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I would also consider renaming this to getBaseConstraintOrUnknown, use ?? instead of ||, and just get rid of the strictNullChecks check.
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Also - any clue if this works on unions of unconstrained type parameters? Can you add a test?
function f<T, U>(x: T | U, y: T | U) {
return x < y;
}
gabritto
previously approved these changes
Jul 19, 2024
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Checking this @typescript-bot perf test this |
DanielRosenwasser
requested changes
Jul 20, 2024
src/compiler/checker.ts
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| @@ -27493,6 +27493,11 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker { | |||
| return type === unknownUnionType ? unknownType : type; | |||
| } | |||
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| // use to determine if a parameter may be undefined or null (or is unknown/unconstrained) | |||
| function getUnknownIfMaybeUnknown(type: Type) { | |||
| return (strictNullChecks && type.flags & TypeFlags.Instantiable) ? getBaseConstraintOfType(type) || unknownType : type; | |||
There was a problem hiding this comment.
I don't know if this it's noticeably different in semantics, but istead of doing this, you might want to try to modify getBaseTypeOfLiteralTypeForComparison and rename it getBaseTypeForComparison. Then pass the result of that into checkNonNullType.
src/compiler/checker.ts
Outdated
| @@ -27493,6 +27493,11 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker { | |||
| return type === unknownUnionType ? unknownType : type; | |||
| } | |||
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| // use to determine if a parameter may be undefined or null (or is unknown/unconstrained) | |||
| function getUnknownIfMaybeUnknown(type: Type) { | |||
| return (strictNullChecks && type.flags & TypeFlags.Instantiable) ? getBaseConstraintOfType(type) || unknownType : type; | |||
There was a problem hiding this comment.
I would also consider renaming this to getBaseConstraintOrUnknown, use ?? instead of ||, and just get rid of the strictNullChecks check.
src/compiler/checker.ts
Outdated
| @@ -27493,6 +27493,11 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker { | |||
| return type === unknownUnionType ? unknownType : type; | |||
| } | |||
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| // use to determine if a parameter may be undefined or null (or is unknown/unconstrained) | |||
| function getUnknownIfMaybeUnknown(type: Type) { | |||
| return (strictNullChecks && type.flags & TypeFlags.Instantiable) ? getBaseConstraintOfType(type) || unknownType : type; | |||
There was a problem hiding this comment.
Also - any clue if this works on unions of unconstrained type parameters? Can you add a test?
function f<T, U>(x: T | U, y: T | U) {
return x < y;
}
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@DanielRosenwasser Here they are:
tscComparison Report - baseline..pr
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tsserverComparison Report - baseline..pr
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startupComparison Report - baseline..pr
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@DanielRosenwasser Thanks for the suggestions! Good catch--it does work for unions but not intersections, so I added those cases as well. |
weswigham
approved these changes
Jul 23, 2024
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@typescript-bot test it |
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@gabritto Here are the results of running the user tests with tsc comparing Everything looks good! |
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Hey @gabritto, the results of running the DT tests are ready. Everything looks the same! |
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@gabritto Here they are:
tscComparison Report - baseline..pr
System info unknown
Hosts
Scenarios
Developer Information: |
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@gabritto Here are the results of running the top 400 repos with tsc comparing Something interesting changed - please have a look. Details
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ahejlsberg
added a commit
that referenced
this pull request
Jul 26, 2024
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I have just put up #59437 which I believe is the right fix for #50603 plus the inconsistencies related to unconstrained type parameters vs. type parameters constrained to |
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fixes #50603, which bisected to #49119
Previously: unconstrained type parameters were inconsistently checked in comparisons, as shown below (5.5.3 playground):
Now with this PR:
This PR does not affect the checking of unconstrained types in other locations.