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-rw-r--r--lib/compiler/src/v3_core.erl66
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{}) ->