Fix parser error for anonymous record type aliases with postfix type operators when closing bracket is column-aligned#19762
Fix parser error for anonymous record type aliases with postfix type operators when closing bracket is column-aligned#19762Copilot wants to merge 2 commits into
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…when closing bracket is aligned with opening bracket
Add BAR_RBRACE to isTypeSeqBlockElementContinuator in LexFilter.fs to prevent incorrect OBLOCKSEP insertion after closing |} in type alias contexts. This fixes the error 'Unexpected symbol [' in member definition' when writing:
type T =
{| Id: Guid
|} [] // or |} seq, |} list, |} option
Add tests covering the fixed cases in AnonymousRecords.fs.
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Co-authored-by: T-Gro <46543583+T-Gro@users.noreply.github.com>
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Clean, well-targeted fix. The root cause analysis is correct: BAR_RBRACE was already handled in isSeqBlockElementContinuator (expression contexts) but was missing from isTypeSeqBlockElementContinuator (type definition contexts), causing spurious OBLOCKSEP insertion when |} is column-aligned.
The one-line change is minimal and mirrors the existing pattern for BAR in the same function. Tests cover the key variants (array, seq, list, option postfixes), multi-field records, and the already-working single-line form as a regression guard.
LGTM.
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When the closing
|}of an anonymous record type alias is vertically aligned with the opening{|, any postfix type operator on the same line causes a spurious parse error:Workarounds were to either indent
|}one extra space or use prefix generic syntax (array<{| Id: Guid |}>, etc.).Root Cause
In
LexFilter.fs, after|}(BAR_RBRACE) closes an anonymous record type, a syntheticODUMMY BAR_RBRACEtoken is queued at that same position. The offside rule for type sequence blocks checksisTypeSeqBlockElementContinuatorto decide whether to insertOBLOCKSEP. SinceBAR_RBRACEwas absent from that function, the dummy token at the same column as the outerCtxtSeqBlocktriggeredOBLOCKSEPinsertion, causing the parser to enter class-member context — where[andseqare invalid.BAR_RBRACEwas already present inisSeqBlockElementContinuator(expression contexts); the type context was simply missing the same treatment.Changes
src/Compiler/SyntaxTree/LexFilter.fs— addBAR_RBRACEtoisTypeSeqBlockElementContinuator, preventing spuriousOBLOCKSEPinsertion after|}in type definition contexts.tests/FSharp.Compiler.ComponentTests/Conformance/Types/RecordTypes/AnonymousRecords.fs— addTypeAliasIndentationmodule with tests covering[],seq,list,optionpostfixes with column-aligned brackets, multi-field records, and the already-working single-line form.