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authorBjörn Gustavsson <[email protected]>2017-05-16 08:08:45 +0200
committerGitHub <[email protected]>2017-05-16 08:08:45 +0200
commit6399c4911bf1c0c717e3cf1c30ac366e8667ad5a (patch)
treeb9b90378456c9bafa1a025022fcfc920a3895ae9
parent8baada6ba97f7809c99cae4e799fddb273a54882 (diff)
parent7b169140b2d37f43996b9d1a94877926a471d97d (diff)
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Merge pull request #1453 from bjorng/bjorn/catch-warning/OTP-14401
Warn for potentially unsafe use of get_stacktrace/0
-rw-r--r--erts/doc/src/erlang.xml28
-rw-r--r--lib/compiler/doc/src/compile.xml8
-rw-r--r--lib/stdlib/src/erl_lint.erl73
-rw-r--r--lib/stdlib/test/erl_lint_SUITE.erl63
4 files changed, 158 insertions, 14 deletions
diff --git a/erts/doc/src/erlang.xml b/erts/doc/src/erlang.xml
index 6f70ae4a52..6d165e9eff 100644
--- a/erts/doc/src/erlang.xml
+++ b/erts/doc/src/erlang.xml
@@ -1813,8 +1813,9 @@ true</pre>
<fsummary>Get the call stack back-trace of the last exception.</fsummary>
<type name="stack_item"/>
<desc>
- <p>Gets the call stack back-trace (<em>stacktrace</em>) of the
- last exception in the calling process as a list of
+ <p>Gets the call stack back-trace (<em>stacktrace</em>) for an
+ exception that has just been caught
+ in the calling process as a list of
<c>{<anno>Module</anno>,<anno>Function</anno>,<anno>Arity</anno>,<anno>Location</anno>}</c>
tuples. Field <c><anno>Arity</anno></c> in the first tuple can be the
argument list of that function call instead of an arity integer,
@@ -1822,6 +1823,29 @@ true</pre>
<p>If there has not been any exceptions in a process, the
stacktrace is <c>[]</c>. After a code change for the process,
the stacktrace can also be reset to <c>[]</c>.</p>
+ <p><c>erlang:get_stacktrace/0</c> is only guaranteed to return
+ a stacktrace if called (directly or indirectly) from within the
+ scope of a <c>try</c> expression. That is, the following call works:</p>
+<pre>
+try Expr
+catch
+ C:R ->
+ {C,R,erlang:get_stacktrace()}
+end</pre>
+ <p>As does this call:</p>
+<pre>
+try Expr
+catch
+ C:R ->
+ {C,R,helper()}
+end
+
+helper() ->
+ erlang:get_stacktrace().</pre>
+
+ <warning><p>In a future release,
+ <c>erlang:get_stacktrace/0</c> will return <c>[]</c> if called
+ from outside a <c>try</c> expression.</p></warning>
<p>The stacktrace is the same data as operator <c>catch</c>
returns, for example:</p>
<pre>
diff --git a/lib/compiler/doc/src/compile.xml b/lib/compiler/doc/src/compile.xml
index fed68037c1..10164890f2 100644
--- a/lib/compiler/doc/src/compile.xml
+++ b/lib/compiler/doc/src/compile.xml
@@ -629,6 +629,14 @@ module.beam: module.erl \
<p>Turns off warnings for unused record types. Default is to
emit warnings for unused locally defined record types.</p>
</item>
+
+ <tag><c>nowarn_get_stacktrace</c></tag>
+ <item>
+ <p>Turns off warnings for using <c>get_stacktrace/0</c> in a context
+ where it will probably not work in a future release. For example,
+ by default there will be a warning if <c>get_stacktrace/0</c> is
+ used following a <c>catch</c> expression.</p>
+ </item>
</taglist>
<p>Another class of warnings is generated by the compiler
diff --git a/lib/stdlib/src/erl_lint.erl b/lib/stdlib/src/erl_lint.erl
index 7c40058dd8..d53a31db0d 100644
--- a/lib/stdlib/src/erl_lint.erl
+++ b/lib/stdlib/src/erl_lint.erl
@@ -92,6 +92,14 @@ value_option(Flag, Default, On, OnVal, Off, OffVal, Opts) ->
:: dict:dict(ta(), line())
}).
+
+%% Are we outside or inside a catch or try/catch?
+-type catch_scope() :: 'none'
+ | 'after_old_catch'
+ | 'after_try'
+ | 'wrong_part_of_try'
+ | 'try_catch'.
+
%% Define the lint state record.
%% 'called' and 'exports' contain {Line, {Function, Arity}},
%% the other function collections contain {Function, Arity}.
@@ -135,7 +143,9 @@ value_option(Flag, Default, On, OnVal, Off, OffVal, Opts) ->
types = dict:new() %Type definitions
:: dict:dict(ta(), #typeinfo{}),
exp_types=gb_sets:empty() %Exported types
- :: gb_sets:set(ta())
+ :: gb_sets:set(ta()),
+ catch_scope = none %Inside/outside try or catch
+ :: catch_scope()
}).
-type lint_state() :: #lint{}.
@@ -223,7 +233,15 @@ format_error({redefine_old_bif_import,{F,A}}) ->
format_error({redefine_bif_import,{F,A}}) ->
io_lib:format("import directive overrides auto-imported BIF ~w/~w~n"
" - use \"-compile({no_auto_import,[~w/~w]}).\" to resolve name clash", [F,A,F,A]);
-
+format_error({get_stacktrace,wrong_part_of_try}) ->
+ "erlang:get_stacktrace/0 used in the wrong part of 'try' expression. "
+ "(Use it in the block between 'catch' and 'end'.)";
+format_error({get_stacktrace,after_old_catch}) ->
+ "erlang:get_stacktrace/0 used following an old-style 'catch' "
+ "may stop working in a future release. (Use it inside 'try'.)";
+format_error({get_stacktrace,after_try}) ->
+ "erlang:get_stacktrace/0 used following a 'try' expression "
+ "may stop working in a future release. (Use it inside 'try'.)";
format_error({deprecated, MFA, ReplacementMFA, Rel}) ->
io_lib:format("~s is deprecated and will be removed in ~s; use ~s",
[format_mfa(MFA), Rel, format_mfa(ReplacementMFA)]);
@@ -568,7 +586,10 @@ start(File, Opts) ->
false, Opts)},
{missing_spec_all,
bool_option(warn_missing_spec_all, nowarn_missing_spec_all,
- false, Opts)}
+ false, Opts)},
+ {get_stacktrace,
+ bool_option(warn_get_stacktrace, nowarn_get_stacktrace,
+ true, Opts)}
],
Enabled1 = [Category || {Category,true} <- Enabled0],
Enabled = ordsets:from_list(Enabled1),
@@ -1405,8 +1426,9 @@ call_function(Line, F, A, #lint{usage=Usage0,called=Cd,func=Func,file=File}=St)
%% function(Line, Name, Arity, Clauses, State) -> State.
function(Line, Name, Arity, Cs, St0) ->
- St1 = define_function(Line, Name, Arity, St0#lint{func={Name,Arity}}),
- clauses(Cs, St1).
+ St1 = St0#lint{func={Name,Arity},catch_scope=none},
+ St2 = define_function(Line, Name, Arity, St1),
+ clauses(Cs, St2).
-spec define_function(line(), atom(), arity(), lint_state()) -> lint_state().
@@ -2338,22 +2360,24 @@ expr({call,Line,F,As}, Vt, St0) ->
expr({'try',Line,Es,Scs,Ccs,As}, Vt, St0) ->
%% Currently, we don't allow any exports because later
%% passes cannot handle exports in combination with 'after'.
- {Evt0,St1} = exprs(Es, Vt, St0),
+ {Evt0,St1} = exprs(Es, Vt, St0#lint{catch_scope=wrong_part_of_try}),
TryLine = {'try',Line},
Uvt = vtunsafe(TryLine, Evt0, Vt),
Evt1 = vtupdate(Uvt, Evt0),
- {Sccs,St2} = icrt_clauses(Scs++Ccs, TryLine, vtupdate(Evt1, Vt), St1),
+ {Sccs,St2} = try_clauses(Scs, Ccs, TryLine,
+ vtupdate(Evt1, Vt), St1),
Rvt0 = Sccs,
Rvt1 = vtupdate(vtunsafe(TryLine, Rvt0, Vt), Rvt0),
Evt2 = vtmerge(Evt1, Rvt1),
{Avt0,St} = exprs(As, vtupdate(Evt2, Vt), St2),
Avt1 = vtupdate(vtunsafe(TryLine, Avt0, Vt), Avt0),
Avt = vtmerge(Evt2, Avt1),
- {Avt,St};
+ {Avt,St#lint{catch_scope=after_try}};
expr({'catch',Line,E}, Vt, St0) ->
%% No new variables added, flag new variables as unsafe.
{Evt,St} = expr(E, Vt, St0),
- {vtupdate(vtunsafe({'catch',Line}, Evt, Vt), Evt),St};
+ {vtupdate(vtunsafe({'catch',Line}, Evt, Vt), Evt),
+ St#lint{catch_scope=after_old_catch}};
expr({match,_Line,P,E}, Vt, St0) ->
{Evt,St1} = expr(E, Vt, St0),
{Pvt,Bvt,St2} = pattern(P, vtupdate(Evt, Vt), St1),
@@ -3173,6 +3197,17 @@ is_module_dialyzer_option(Option) ->
error_handling,race_conditions,no_missing_calls,
specdiffs,overspecs,underspecs,unknown]).
+%% try_catch_clauses(Scs, Ccs, In, ImportVarTable, State) ->
+%% {UpdVt,State}.
+
+try_clauses(Scs, Ccs, In, Vt, St0) ->
+ {Csvt0,St1} = icrt_clauses(Scs, Vt, St0),
+ St2 = St1#lint{catch_scope=try_catch},
+ {Csvt1,St3} = icrt_clauses(Ccs, Vt, St2),
+ Csvt = Csvt0 ++ Csvt1,
+ UpdVt = icrt_export(Csvt, Vt, In, St3),
+ {UpdVt,St3}.
+
%% icrt_clauses(Clauses, In, ImportVarTable, State) ->
%% {UpdVt,State}.
@@ -3657,7 +3692,8 @@ has_wildcard_field([]) -> false.
check_remote_function(Line, M, F, As, St0) ->
St1 = deprecated_function(Line, M, F, As, St0),
St2 = check_qlc_hrl(Line, M, F, As, St1),
- format_function(Line, M, F, As, St2).
+ St3 = check_get_stacktrace(Line, M, F, As, St2),
+ format_function(Line, M, F, As, St3).
%% check_qlc_hrl(Line, ModName, FuncName, [Arg], State) -> State
%% Add warning if qlc:q/1,2 has been called but qlc.hrl has not
@@ -3706,6 +3742,23 @@ deprecated_function(Line, M, F, As, St) ->
St
end.
+check_get_stacktrace(Line, erlang, get_stacktrace, [], St) ->
+ case St of
+ #lint{catch_scope=none} ->
+ St;
+ #lint{catch_scope=try_catch} ->
+ St;
+ #lint{catch_scope=Scope} ->
+ case is_warn_enabled(get_stacktrace, St) of
+ false ->
+ St;
+ true ->
+ add_warning(Line, {get_stacktrace,Scope}, St)
+ end
+ end;
+check_get_stacktrace(_, _, _, _, St) ->
+ St.
+
-dialyzer({no_match, deprecated_type/5}).
deprecated_type(L, M, N, As, St) ->
diff --git a/lib/stdlib/test/erl_lint_SUITE.erl b/lib/stdlib/test/erl_lint_SUITE.erl
index 03cad2c093..02524679fa 100644
--- a/lib/stdlib/test/erl_lint_SUITE.erl
+++ b/lib/stdlib/test/erl_lint_SUITE.erl
@@ -65,7 +65,8 @@
maps/1,maps_type/1,maps_parallel_match/1,
otp_11851/1,otp_11879/1,otp_13230/1,
record_errors/1, otp_11879_cont/1,
- non_latin1_module/1, otp_14323/1]).
+ non_latin1_module/1, otp_14323/1,
+ get_stacktrace/1]).
suite() ->
[{ct_hooks,[ts_install_cth]},
@@ -85,7 +86,8 @@ all() ->
too_many_arguments, basic_errors, bin_syntax_errors, predef,
maps, maps_type, maps_parallel_match,
otp_11851, otp_11879, otp_13230,
- record_errors, otp_11879_cont, non_latin1_module, otp_14323].
+ record_errors, otp_11879_cont, non_latin1_module, otp_14323,
+ get_stacktrace].
groups() ->
[{unused_vars_warn, [],
@@ -3980,6 +3982,63 @@ otp_14323(Config) ->
[] = run(Config, Ts),
ok.
+get_stacktrace(Config) ->
+ Ts = [{old_catch,
+ <<"t1() ->
+ catch error(foo),
+ erlang:get_stacktrace().
+ ">>,
+ [],
+ {warnings,[{3,erl_lint,{get_stacktrace,after_old_catch}}]}},
+ {nowarn_get_stacktrace,
+ <<"t1() ->
+ catch error(foo),
+ erlang:get_stacktrace().
+ ">>,
+ [nowarn_get_stacktrace],
+ []},
+ {try_catch,
+ <<"t1(X) ->
+ try abs(X) of
+ _ ->
+ erlang:get_stacktrace()
+ catch
+ _:_ -> ok
+ end.
+
+ t2() ->
+ try error(foo)
+ catch _:_ -> ok
+ end,
+ erlang:get_stacktrace().
+
+ t3() ->
+ try error(foo)
+ catch _:_ ->
+ try error(bar)
+ catch _:_ ->
+ ok
+ end,
+ erlang:get_stacktrace()
+ end.
+
+ no_warning(X) ->
+ try
+ abs(X)
+ catch
+ _:_ ->
+ erlang:get_stacktrace()
+ end.
+ ">>,
+ [],
+ {warnings,[{4,erl_lint,{get_stacktrace,wrong_part_of_try}},
+ {13,erl_lint,{get_stacktrace,after_try}},
+ {22,erl_lint,{get_stacktrace,after_try}}]}}],
+
+ run(Config, Ts),
+ ok.
+
+
run(Config, Tests) ->
F = fun({N,P,Ws,E}, BadL) ->
case catch run_test(Config, P, Ws) of