Port TypeScript PR #62243: Improve inference by not considering thisless functions context-sensitive

[Copilot]

• Binder: Add PropagatesThisKeyword container flag - New flag for signatures and arrow functions to propagate seenThisKeyword upward
• Binder: Track seenThisKeyword in control flow containers - Save/restore seenThisKeyword, set NodeFlagsContainsThis on function-like nodes, handle propagation
• Binder: Set seenThisKeyword for ThisKeyword - Mark seenThisKeyword = true when binding KindThisKeyword
• Binder: Save/restore seenThisKeyword around interfaces - Ensure interface containers don't leak seenThisKeyword
• Binder: Clear ContainsThis flag along with reachability flags - Reset ContainsThis before recalculating
• AST utilities: Update HasContextSensitiveParameters - Check node.Flags & NodeFlagsContainsThis instead of unconditionally returning true
• Checker utilities: Update forEachYieldExpression - Return bool with early termination semantics
• Checker: Add YieldExpression to isContextSensitive - Handle yield expressions for context sensitivity
• Checker: Add hasContextSensitiveYieldExpression - New function for generator context sensitivity
• Checker: Update isContextSensitiveFunctionLikeDeclaration - Add hasContextSensitiveYieldExpression check
• Checker: Update instantiateContextualType - Skip returning instantiated types when result is any or unknown
• Checker: Clear SkipGenericFunctions when checking yield expression operands - Match TS behavior, fix generator inference
• Build succeeds and all tests pass
• Accept baseline changes (net ~1000 lines deleted from diff files)
• No new diffs introduced
• Code review and security checks

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[jakebailey]

@copilot This seems like an improvement, but there are diffs introduced, which indicates that something is wrong.

[Copilot]

@copilot This seems like an improvement, but there are diffs introduced, which indicates that something is wrong.

Fixed in fe78f7b with two changes:

1. Restored PropertyDeclaration in GetContainerFlags — The Go binder uses IsThisContainer on property declarations with initializers for JS class property binding (a Go-specific mechanism). Removing it broke classFieldSuperNotAccessibleJs.

2. Fixed pre-existing bug: clear CheckModeSkipGenericFunctions when checking yield expression operands — Go wasn't matching TS's checkMode & ~CheckMode.SkipGenericFunctions in checkAndAggregateYieldOperandTypes. This was masked before because generators were always context-sensitive (checked in second pass without SkipGenericFunctions). This fix resolves genericCallAtYieldExpressionInGenericCall3, deletes genericCallAtYieldExpressionInGenericCall2 errors, and improves genericCallAtYieldExpressionInGenericCall1.

Net result: ~1000 lines deleted from diff files, no new diffs introduced.

[Copilot]

Pull request overview

Ports TypeScript PR #62243 to the Go compiler port, refining “context sensitivity” (especially around this usage) to improve inference and align baseline outputs with upstream TypeScript.

Changes:

• Binder now tracks whether function-like nodes actually contain this (with propagation through arrows/signatures) and uses that to drive context-sensitivity decisions.
• Checker updates context-sensitivity logic for generators (yield expressions) and adjusts contextual type instantiation to avoid returning any/unknown instantiations.
• Updates/accepts numerous submodule baselines to reflect the new inference and diagnostic behavior.

Reviewed changes

Copilot reviewed 40 out of 40 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
testdata/baselines/reference/submodule/conformance/thisTypeInFunctions.types.diff	Removes now-obsolete diff baseline for updated this typing output.
testdata/baselines/reference/submodule/conformance/thisTypeInFunctions.types	Updates expected types output for this-related function scenarios.
testdata/baselines/reference/submodule/compiler/vueLikeDataAndPropsInference2.types.diff	Adjusts diff baseline to match new contextual typing behavior.
testdata/baselines/reference/submodule/compiler/vueLikeDataAndPropsInference2.types	Updates expected types output for Vue-like inference case (data this typing changes).
testdata/baselines/reference/submodule/compiler/vueLikeDataAndPropsInference.types.diff	Adjusts diff baseline to match new contextual typing behavior.
testdata/baselines/reference/submodule/compiler/vueLikeDataAndPropsInference.types	Updates expected types output for Vue-like inference case (data this typing changes).
testdata/baselines/reference/submodule/compiler/thislessFunctionsNotContextSensitive3.types.diff	Updates/removes diff content due to new “thisless” context sensitivity behavior.
testdata/baselines/reference/submodule/compiler/thislessFunctionsNotContextSensitive3.types	Updates expected types output for “thisless functions not context sensitive” scenario.
testdata/baselines/reference/submodule/compiler/thislessFunctionsNotContextSensitive3.symbols.diff	Removes now-obsolete symbols diff baseline.
testdata/baselines/reference/submodule/compiler/thislessFunctionsNotContextSensitive3.symbols	Updates expected symbol output due to changed contextual typing/inference.
testdata/baselines/reference/submodule/compiler/thislessFunctionsNotContextSensitive3.errors.txt.diff	Removes now-obsolete errors diff baseline.
testdata/baselines/reference/submodule/compiler/thislessFunctionsNotContextSensitive3.errors.txt	Updates expected diagnostics output/counts for the scenario.
testdata/baselines/reference/submodule/compiler/thislessFunctionsNotContextSensitive2.types.diff	Removes now-obsolete types diff baseline.
testdata/baselines/reference/submodule/compiler/thislessFunctionsNotContextSensitive2.types	Updates expected types output for “thisless functions not context sensitive” scenario.
testdata/baselines/reference/submodule/compiler/thislessFunctionsNotContextSensitive1.types.diff	Updates/removes diff content due to new inference behavior.
testdata/baselines/reference/submodule/compiler/thislessFunctionsNotContextSensitive1.types	Updates expected types output for “thisless functions not context sensitive” scenario.
testdata/baselines/reference/submodule/compiler/thislessFunctionsNotContextSensitive1.symbols.diff	Removes now-obsolete symbols diff baseline.
testdata/baselines/reference/submodule/compiler/thislessFunctionsNotContextSensitive1.symbols	Updates expected symbol output due to changed inference.
testdata/baselines/reference/submodule/compiler/thislessFunctionsNotContextSensitive1.errors.txt.diff	Removes now-obsolete errors diff baseline.
testdata/baselines/reference/submodule/compiler/thislessFunctionsNotContextSensitive1.errors.txt	Updates expected diagnostics output/counts for the scenario.
testdata/baselines/reference/submodule/compiler/returnTypeInferenceContextualTypeIgnoreAnyUnknown1.types.diff	Removes now-obsolete types diff baseline.
testdata/baselines/reference/submodule/compiler/returnTypeInferenceContextualTypeIgnoreAnyUnknown1.types	Updates expected types output related to contextual typing + any/unknown handling.
testdata/baselines/reference/submodule/compiler/returnTypeInferenceContextualTypeIgnoreAnyUnknown1.errors.txt.diff	Removes now-obsolete errors diff baseline.
testdata/baselines/reference/submodule/compiler/returnTypeInferenceContextualTypeIgnoreAnyUnknown1.errors.txt	Removes baseline file content (now no longer expected).
testdata/baselines/reference/submodule/compiler/redefineArray.types.diff	Removes now-obsolete types diff baseline.
testdata/baselines/reference/submodule/compiler/redefineArray.types	Updates expected types output for Array reassignment case.
testdata/baselines/reference/submodule/compiler/redefineArray.errors.txt.diff	Removes now-obsolete errors diff baseline.
testdata/baselines/reference/submodule/compiler/redefineArray.errors.txt	Updates expected diagnostic formatting/output.
testdata/baselines/reference/submodule/compiler/genericCallAtYieldExpressionInGenericCall2.errors.txt.diff	Removes now-obsolete errors diff baseline.
testdata/baselines/reference/submodule/compiler/genericCallAtYieldExpressionInGenericCall2.errors.txt	Removes baseline file content (now no longer expected).
testdata/baselines/reference/submodule/compiler/genericCallAtYieldExpressionInGenericCall1.types.diff	Updates/removes diff content due to yield inference changes.
testdata/baselines/reference/submodule/compiler/genericCallAtYieldExpressionInGenericCall1.types	Updates expected types output for yield inference behavior.
testdata/baselines/reference/submodule/compiler/genericCallAtYieldExpressionInGenericCall1.errors.txt.diff	Updates diff baseline for yield-related diagnostics changes.
testdata/baselines/reference/submodule/compiler/genericCallAtYieldExpressionInGenericCall1.errors.txt	Updates expected diagnostics output/counts for yield inference behavior.
testdata/baselines/reference/submodule/compiler/circularlySimplifyingConditionalTypesNoCrash.types.diff	Removes now-obsolete types diff baseline.
testdata/baselines/reference/submodule/compiler/circularlySimplifyingConditionalTypesNoCrash.types	Updates expected types output for conditional type simplification case.
internal/checker/utilities.go	Changes forEachYieldExpression to return bool for early-termination traversal semantics.
internal/checker/checker.go	Updates yield operand checking, context-sensitivity to include yield, and avoids returning instantiated any/unknown contextual types.
internal/binder/binder.go	Adds ContainerFlagsPropagatesThisKeyword and tracks/propagates seenThisKeyword to set NodeFlagsContainsThis appropriately.
internal/ast/utilities.go	Updates HasContextSensitiveParameters to use NodeFlagsContainsThis instead of treating implicit-this functions as always context-sensitive.

[DanielRosenwasser]

microsoft/TypeScript#62243