[Mateusz Burzyński (Andarist)]

Just a potential minor optimization

project	contextual calls	contextual bails	contextual names skipped	relation calls	relation bails	relation names skipped
vscode	222,110	94,641 (43%)	488,900	11,337	1,078	3,265
xstate	110,649	69,190 (63%)	128,903	3,307	557	1,032
xstate-5	85,567	55,380 (65%)	105,169	2,068	451	858
arktype	13,641	1,920 (14%)	4,212	1,413	147	410
Compiler-Unions	2,618	1,547 (59%)	196,559	106	0	0

in the above table:
relation -> findMatchingDiscriminantType reached from excess property checking
names skipped -> upper bound of individual property names that would otherwise be passed through isDiscriminantProperty

[typescript-automation]

This PR doesn't have any linked issues. Please open an issue that references this PR. From there we can discuss and prioritise.

[Copilot]

🟡 Changes recommended

The contextual-typing early returns skip primitive filtering, suppressing deprecated-property suggestions for nullable object and JSX contextual types.

1 open issue

• Preserve primitive filtering in nullable contextual typing fast paths · New

What changed in this PR

This PR aims to reduce compiler work by skipping discriminant lookups for unions with fewer than two non-primitive constituents.

Changes:

• Adds a shared eligibility check for discriminant-based narrowing.
• Applies early exits to type matching and contextual typing for object literals and JSX attributes.

File	Description
tsc/​internal/​checker/​relater.go	Adds the union eligibility helper and guards discriminant matching.
tsc/​internal/​checker/​jsx.go	Adds an early exit for JSX contextual discrimination.
tsc/​internal/​checker/​checker.go	Adds an early exit for object-literal contextual discrimination.

_{Review effort: Balanced}

[Copilot]

🟡 Changes recommended

Both contextual fast paths bypass existing caching, causing repeated union filtering and allocations for property and attribute queries.

1 open issue

• Check and populate contextual-type cache before early guard · New

1 resolved since last review

• Preserve primitive filtering in nullable contextual typing fast paths

_{Review effort: Balanced}

[Mateusz Burzyński (Andarist)]

I measured this and couldn't find this to make any different for any project. Also, the result is node-independent so the per-node cache wouldnt fit this all too well. I could add a second type-based cache but I couldn't prove anyhow it would actually be worth it.