From 4c31fd0b966571508b4eb5170ddb0b38fbaf5fc0 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= Date: Tue, 29 Aug 2017 18:02:49 +0200 Subject: Make handling of match contexts stricter beam_validator could fail issue a diagnostic when a register that was supposed to be a match context was not guaranteed to be a match context. The bug was in merging of types. Merging of a match context with another term would result in a match context. That is wrong. Merging should produce a more general type, not a narrower type. Also, the valid slots in two match contexts should be combined with 'band', not 'bor'. --- lib/compiler/src/beam_validator.erl | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/lib/compiler/src/beam_validator.erl b/lib/compiler/src/beam_validator.erl index 622e00bb2b..00901077d3 100644 --- a/lib/compiler/src/beam_validator.erl +++ b/lib/compiler/src/beam_validator.erl @@ -1430,13 +1430,13 @@ merge_types(bool, {atom,A}) -> merge_bool(A); merge_types({atom,A}, bool) -> merge_bool(A); -merge_types(#ms{id=Id,valid=B0,slots=Slots}=M, - #ms{id=Id,valid=B1,slots=Slots}) -> - M#ms{valid=B0 bor B1,slots=Slots}; -merge_types(#ms{}=M, _) -> - M; -merge_types(_, #ms{}=M) -> - M; +merge_types(#ms{id=Id1,valid=B0,slots=Slots}, + #ms{id=Id2,valid=B1,slots=Slots}) -> + Id = if + Id1 =:= Id2 -> Id1; + true -> make_ref() + end, + #ms{id=Id,valid=B0 band B1,slots=Slots}; merge_types(T1, T2) when T1 =/= T2 -> %% Too different. All we know is that the type is a 'term'. term. -- cgit v1.2.3