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authorHaitao Li <[email protected]>2011-08-26 10:21:41 +0800
committerHenrik Nord <[email protected]>2011-09-08 09:39:56 +0200
commit29610af8d3db844568cffc4218f79fc68bfd8094 (patch)
tree3367a75b78c1cb336443b4043a92e98961eb3b81 /lib
parent22dae863060e0d66fa268f6d1cd4d6f084b850ab (diff)
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ms_transform: Fix incorrect `variable shadowed' warnings
Compile below module resulting incorrect warning: $ cat tmp.erl -module(tmp). -export([tmp/1]). -include_lib("stdlib/include/ms_transform.hrl"). tmp(X) when X > 100 -> Y=X, Y; tmp(X) -> ets:fun2ms(fun(Y) -> {X, Y} end). $ erlc tmp.erl ./tmp.erl:8: Warning: variable 'Y' shadowed in ms_transform fun head The scope for a variable is its function clause. Variables bound in one function clause should not interfere with other function clauses. This patch removes incorrect passing of variable bindings from one function clause to another. Signed-off-by: Haitao Li <[email protected]>
Diffstat (limited to 'lib')
-rw-r--r--lib/stdlib/src/ms_transform.erl17
-rw-r--r--lib/stdlib/test/ms_transform_SUITE.erl45
2 files changed, 53 insertions, 9 deletions
diff --git a/lib/stdlib/src/ms_transform.erl b/lib/stdlib/src/ms_transform.erl
index 48e22e53fa..63b397f3a5 100644
--- a/lib/stdlib/src/ms_transform.erl
+++ b/lib/stdlib/src/ms_transform.erl
@@ -333,17 +333,18 @@ form({function,Line,Name0,Arity0,Clauses0}) ->
form(AnyOther) ->
AnyOther.
function(Name, Arity, Clauses0) ->
- {Clauses1,_} = clauses(Clauses0,gb_sets:new()),
+ Clauses1 = clauses(Clauses0),
{Name,Arity,Clauses1}.
-clauses([C0|Cs],Bound) ->
- {C1,Bound1} = clause(C0,Bound),
- {C2,Bound2} = clauses(Cs,Bound1),
- {[C1|C2],Bound2};
-clauses([],Bound) -> {[],Bound}.
+clauses([C0|Cs]) ->
+ C1 = clause(C0,gb_sets:new()),
+ C2 = clauses(Cs),
+ [C1|C2];
+clauses([]) -> [].
+
clause({clause,Line,H0,G0,B0},Bound) ->
{H1,Bound1} = copy(H0,Bound),
- {B1,Bound2} = copy(B0,Bound1),
- {{clause,Line,H1,G0,B1},Bound2}.
+ {B1,_Bound2} = copy(B0,Bound1),
+ {clause,Line,H1,G0,B1}.
copy({call,Line,{remote,_Line2,{atom,_Line3,ets},{atom,_Line4,fun2ms}},
As0},Bound) ->
diff --git a/lib/stdlib/test/ms_transform_SUITE.erl b/lib/stdlib/test/ms_transform_SUITE.erl
index 4e5df12798..c9688354b1 100644
--- a/lib/stdlib/test/ms_transform_SUITE.erl
+++ b/lib/stdlib/test/ms_transform_SUITE.erl
@@ -39,6 +39,7 @@
-export([float_1_function/1]).
-export([action_function/1]).
-export([warnings/1]).
+-export([no_warnings/1]).
-export([init_per_testcase/2, end_per_testcase/2]).
init_per_testcase(_Func, Config) ->
@@ -55,7 +56,7 @@ all() ->
[from_shell, basic_ets, basic_dbg, records,
record_index, multipass, bitsyntax, record_defaults,
andalso_orelse, float_1_function, action_function,
- warnings, top_match, old_guards, autoimported,
+ warnings, no_warnings, top_match, old_guards, autoimported,
semicolon].
groups() ->
@@ -155,6 +156,34 @@ warnings(Config) when is_list(Config) ->
compile_ww(Prog7),
ok.
+no_warnings(suite) ->
+ [];
+no_warnings(doc) ->
+ ["Check that variables bound in other function clauses don't generate "
+ "warning"];
+no_warnings(Config) when is_list(Config) ->
+ ?line setup(Config),
+ Prog = <<"tmp(X) when X > 100 ->\n",
+ " Y=X,\n"
+ " Y;\n"
+ "tmp(X) ->\n"
+ " ets:fun2ms(fun(Y) ->\n"
+ " {X, 3*Y}\n"
+ " end)">>,
+ ?line [] = compile_no_ww(Prog),
+
+ Prog2 = <<"tmp(X) when X > 100 ->\n",
+ " Y=X,\n"
+ " Y;\n"
+ "tmp(X) when X < 200 ->\n"
+ " ok;\n"
+ "tmp(X) ->\n"
+ " ets:fun2ms(fun(Y) ->\n"
+ " {X, 3*Y}\n"
+ " end)">>,
+ ?line [] = compile_no_ww(Prog2),
+ ok.
+
andalso_orelse(suite) ->
[];
andalso_orelse(doc) ->
@@ -842,6 +871,20 @@ compile_ww(Records,Expr) ->
nowarn_unused_record]),
Wlist.
+compile_no_ww(Expr) ->
+ Prog = <<
+ "-module(tmp).\n",
+ "-include_lib(\"stdlib/include/ms_transform.hrl\").\n",
+ "-export([tmp/1]).\n\n",
+ Expr/binary,".\n">>,
+ FN=temp_name(),
+ file:write_file(FN,Prog),
+ {ok,Forms} = epp:parse_file(FN,"",""),
+ {ok,tmp,_Bin,Wlist} = compile:forms(Forms,[return_warnings,
+ nowarn_unused_vars,
+ nowarn_unused_record]),
+ Wlist.
+
do_eval(String) ->
{done,{ok,T,_},[]} = erl_scan:tokens(
[],