Only resolve obligations for is_never checks on bare type variables [-0.18% avg] - #102
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Only resolve obligations for is_never checks on bare type variables [-0.18% avg]#102xmakro wants to merge 1 commit into
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…bles Both never-type checks in expression checking ran a full fulfillment round-trip whenever the expression type contained any inference variable, though the type is already resolved at that point and only a bare type variable can still become !. Answer from the type kind and keep the expensive path for the type-variable case. Also deduplicates repeated 'constant expression depends on a generic parameter' errors, since anonymous const obligations are no longer re-selected once per enclosing expression.
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Both never-type checks in expression checking ran a full fulfillment round-trip whenever the expression type contained any inference variable, though the type is already resolved at that point and only a bare type variable can still become the never type. Answer from the type kind and keep the expensive path for the type-variable case.
This also deduplicates repeated 'constant expression depends on a generic parameter' errors, since anonymous const obligations are no longer re-selected once per enclosing expression. On the July base this needed 7 ui test blesses, all benign: five from the error deduplication, two from the same lints emitted in source order instead of query-completion order.
Measured alone at head 969b803 (clean from-scratch ThinLTO plus jemalloc stage2 build per side, instructions:u, Check/Debug/Opt across Full/IncrFull/IncrUnchanged/IncrPatched, 551 cells): -0.18% mean, 44 cells improved by at least 0.25%, 1 regressed. Top cells: wg-grammar-new-solver -4.8% to -5.3% across profiles, deep-vector -4.1% to -4.5%. The largest single slice of the old combined branch.