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-rw-r--r--lib/compiler/src/sys_core_fold.erl37
1 files changed, 27 insertions, 10 deletions
diff --git a/lib/compiler/src/sys_core_fold.erl b/lib/compiler/src/sys_core_fold.erl
index f17b0bd130..fbd7452301 100644
--- a/lib/compiler/src/sys_core_fold.erl
+++ b/lib/compiler/src/sys_core_fold.erl
@@ -2672,16 +2672,19 @@ bsm_nonempty([#c_clause{pats=Ps}|Cs], Pos) ->
bsm_nonempty([], _ ) -> false.
%% bsm_ensure_no_partition(Cs, Pos) -> ok (exception if problem)
-%% We must make sure that binary matching is not partitioned between
+%% We must make sure that matching is not partitioned between
%% variables like this:
%% foo(<<...>>) -> ...
-%% foo(Var) when ... -> ...
-%% foo(<<...>>) ->
+%% foo(<Variable>) when ... -> ...
+%% foo(<Any non-variable pattern>) ->
%% If there is such partition, we are not allowed to reuse the binary variable
-%% for the match context. Also, arguments to the left of the argument that
-%% is matched against a binary, are only allowed to be simple variables, not
-%% used in guards. The reason is that we must know that the binary is only
-%% matched in one place.
+%% for the match context.
+%%
+%% Also, arguments to the left of the argument that is matched
+%% against a binary, are only allowed to be simple variables, not
+%% used in guards. The reason is that we must know that the binary is
+%% only matched in one place (i.e. there must be only one bs_start_match2
+%% instruction emitted).
bsm_ensure_no_partition(Cs, Pos) ->
bsm_ensure_no_partition_1(Cs, Pos, before).
@@ -2689,6 +2692,12 @@ bsm_ensure_no_partition(Cs, Pos) ->
%% Loop through each clause.
bsm_ensure_no_partition_1([#c_clause{pats=Ps,guard=G}|Cs], Pos, State0) ->
State = bsm_ensure_no_partition_2(Ps, Pos, G, simple_vars, State0),
+ case State of
+ 'after' ->
+ bsm_ensure_no_partition_after(Cs, Pos);
+ _ ->
+ ok
+ end,
bsm_ensure_no_partition_1(Cs, Pos, State);
bsm_ensure_no_partition_1([], _, _) -> ok.
@@ -2698,8 +2707,7 @@ bsm_ensure_no_partition_2([#c_binary{}=Where|_], 1, _, Vstate, State) ->
before when Vstate =:= simple_vars -> within;
before -> bsm_problem(Where, Vstate);
within when Vstate =:= simple_vars -> within;
- within -> bsm_problem(Where, Vstate);
- 'after' -> bsm_problem(Where, bin_partition)
+ within -> bsm_problem(Where, Vstate)
end;
bsm_ensure_no_partition_2([#c_alias{}=Alias|_], 1, N, Vstate, State) ->
%% Retrieve the real pattern that the alias refers to and check that.
@@ -2748,6 +2756,15 @@ bsm_ensure_no_partition_2([#c_var{name=V}|Ps], N, G, Vstate, S) ->
bsm_ensure_no_partition_2([_|Ps], N, G, _, S) ->
bsm_ensure_no_partition_2(Ps, N-1, G, bin_argument_order, S).
+bsm_ensure_no_partition_after([#c_clause{pats=Ps}|Cs], Pos) ->
+ case nth(Pos, Ps) of
+ #c_var{} ->
+ bsm_ensure_no_partition_after(Cs, Pos);
+ P ->
+ bsm_problem(P, bin_partition)
+ end;
+bsm_ensure_no_partition_after([], _) -> ok.
+
bsm_could_match_binary(#c_alias{pat=P}) -> bsm_could_match_binary(P);
bsm_could_match_binary(#c_cons{}) -> false;
bsm_could_match_binary(#c_tuple{}) -> false;
@@ -2872,7 +2889,7 @@ format_error(useless_building) ->
format_error(bin_opt_alias) ->
"INFO: the '=' operator will prevent delayed sub binary optimization";
format_error(bin_partition) ->
- "INFO: non-consecutive clauses that match binaries "
+ "INFO: matching non-variables after a previous clause matching a variable "
"will prevent delayed sub binary optimization";
format_error(bin_left_var_used_in_guard) ->
"INFO: a variable to the left of the binary pattern is used in a guard; "