With this commit, the new broken test case passes. The main issue is not clearly separating temporary variables in mach-guards from public variables. * share/txr/stdlib/match.tl (match-vars): Remove pure-vars and pure-var-exprs from this inheritance base, as well as the related lets method. (match-guard): Add the "pure" slots here, under new names: pure-temps and pure-temp-exprs. This renaming is for clarity. Add the lets method here, based on these new variables. Add new slots temps, representing the impure temps. There is no temp-exprs because impure temps are bound to nil and later assigned. (compiled-match get-temps): Method removed. (compiled-match get-vars): Rewritten to avoid using get-temps which doesn't exist any more. This method has a clear purpose: to all the public variables coming from the patterns themselves, whether those variables are promoted into a guard-chain for early binding or whether they are attached on the compiled-match object. (compiled-match wrap-guards): Ensure that the new temps from the guard-chain objects are bound with let. (compile-struct-match, compile-vec-match, compile-range-match, compile-dwim-predicate-match, compile-cons-structure, compile-hash-match): pure-vars rename. (compile-loop-match): We no longer bind cm.(get-temps) here. That method doesn't exist. If we are not doing @(some), we bind cm-vars: the public vars collected from cm. We need local copies of them to catch their values and accumulate them into list. In the match-guard constructor, we move the collect-gens into temps; they are not public variables. (compile-parallel-match): Drop ^(let ,pm.(get-temps) ...) from the expansion.