diff options
Diffstat (limited to 'lib/compiler/src')
| -rw-r--r-- | lib/compiler/src/v3_core.erl | 66 |
1 files changed, 53 insertions, 13 deletions
diff --git a/lib/compiler/src/v3_core.erl b/lib/compiler/src/v3_core.erl index 83b3650180..a3b0236134 100644 --- a/lib/compiler/src/v3_core.erl +++ b/lib/compiler/src/v3_core.erl @@ -510,16 +510,8 @@ unforce(_, Vs) -> Vs. exprs([E0|Es0], St0) -> {E1,Eps,St1} = expr(E0, St0), - case E1 of - #iprimop{name=#c_literal{val=match_fail}} -> - %% Must discard the rest of the body, because it - %% may refer to variables that have not been bound. - %% Example: {ok={error,E}} = foo(), E. - {Eps ++ [E1],St1}; - _ -> - {Es1,St2} = exprs(Es0, St1), - {Eps ++ [E1] ++ Es1,St2} - end; + {Es1,St2} = exprs(Es0, St1), + {Eps ++ [E1] ++ Es1,St2}; exprs([], St) -> {[],St}. %% expr(Expr, State) -> {Cexpr,[PreExp],State}. @@ -689,14 +681,36 @@ expr({match,L,P0,E0}, St0) -> Fc = fail_clause([Fpat], Lanno, c_tuple([#c_literal{val=badmatch},Fpat])), case P2 of nomatch -> + %% The pattern will not match. We must take care here to + %% bind all variables that the pattern would have bound + %% so that subsequent expressions do not refer to unbound + %% variables. + %% + %% As an example, this code: + %% + %% [X] = {Y} = E, + %% X + Y. + %% + %% will be rewritten to: + %% + %% error({badmatch,E}), + %% case E of + %% {[X],{Y}} -> + %% X + Y; + %% Other -> + %% error({badmatch,Other}) + %% end. + %% St6 = add_warning(L, nomatch, St5), - {Expr,Eps3,St} = safe(E1, St6), - Eps = Eps1 ++ Eps2 ++ Eps3, + {Expr,Eps3,St7} = safe(E1, St6), + SanPat0 = sanitize(P1), + {SanPat,Eps4,St} = pattern(SanPat0, St7), Badmatch = c_tuple([#c_literal{val=badmatch},Expr]), Fail = #iprimop{anno=#a{anno=Lanno}, name=#c_literal{val=match_fail}, args=[Badmatch]}, - {Fail,Eps,St}; + Eps = Eps3 ++ Eps4 ++ [Fail], + {#imatch{anno=#a{anno=Lanno},pat=SanPat,arg=Expr,fc=Fc},Eps,St}; Other when not is_atom(Other) -> {#imatch{anno=#a{anno=Lanno},pat=P2,arg=E2,fc=Fc},Eps1++Eps2,St5} end; @@ -738,6 +752,32 @@ expr({op,L,Op,L0,R0}, St0) -> module=#c_literal{anno=LineAnno,val=erlang}, name=#c_literal{anno=LineAnno,val=Op},args=As},Aps,St1}. + +%% sanitize(Pat) -> SanitizedPattern +%% Rewrite Pat so that it will be accepted by pattern/2 and will +%% bind the same variables as the original pattern. +%% +%% Here is an example of a pattern that would cause a pattern/2 +%% to generate a 'nomatch' exception: +%% +%% #{k:=X,k:=Y} = [Z] +%% +%% The sanitized pattern will look like: +%% +%% {{X,Y},[Z]} + +sanitize({match,L,P1,P2}) -> + {tuple,L,[sanitize(P1),sanitize(P2)]}; +sanitize({cons,L,H,T}) -> + {cons,L,sanitize(H),sanitize(T)}; +sanitize({tuple,L,Ps0}) -> + Ps = [sanitize(P) || P <- Ps0], + {tuple,L,Ps}; +sanitize({map,L,Ps0}) -> + Ps = [sanitize(V) || {map_field_exact,_,_,V} <- Ps0], + {tuple,L,Ps}; +sanitize(P) -> P. + make_bool_switch(L, E, V, T, F, #core{in_guard=true}) -> make_bool_switch_guard(L, E, V, T, F); make_bool_switch(L, E, V, T, F, #core{}) -> |