[erlang-patches] [erlang-bugs] Compiler crash with 'inline_list_funcs' and "fun Fun/Arity" notation

[Björn Gustavsson]

Thanks! Looks good. I have only two slight comments:

If find the first sentence in the commit message confusing:

"Local fun references look like plain old variables in the Core Erlang
AST and should not be treated as such."

I would suggest "but" instead of "and":

"Local fun references look like plain old variables in the Core Erlang
AST, but should not be treated as such."

The test cases tests that the compiler does not crash and that
the code can be loaded, but it does not test that the code actually
works. I suggest that you rewrite it to something like this:

?MODULE() ->
    F = fun bar/1,
    G = lists:last([(fun (X) when F =:= X -> X end)]),
    F = G(F),
    ok.

bar(X) ->
    X.

/Bjorn



On Sat, May 18, 2013 at 6:22 PM, Anthony Ramine <n.oxyde@REDACTED> wrote:

> Hello,
>
> This patch fixes the bug by forbidding inlining of variables which values
> are local fun references outside of application contexts.
>
>         git fetch https://github.com/nox/otp.git fix-fname-inlining
>
>
> https://github.com/nox/otp/compare/erlang:maint...fix-fname-inlining
>
> https://github.com/nox/otp/compare/erlang:maint...fix-fname-inlining.patch
>
> Regards,
>
> --
> Anthony Ramine
>
> Le 17 mai 2013 à 20:06, Anthony Ramine a écrit :
>
> > Hello,
> >
> > Shorter test case, showing the problem comes from the inline itself and
> not inline_list_funcs:
> >
> > -module(test).
> > -compile(inline).
> > -export([foo/0]).
> >
> > foo() ->
> >    F = fun bar/1,
> >    fun (X) when X =:= F -> X end.
> >
> > bar(X) -> X.
> >
> > If you run the core_lint pass, you can see where the problem comes from:
> >
> > $ erlc +clint test.erl
> > test: illegal guard expression in foo/0
> >
> > The inliner inlines `when 'erlang':'=:='(X, F)` to `'erlang':'=:='(X,
> 'bar'/1)` but local fun references can't appear in guards.
> >
> > I'll try to make a patch.
> >
> > Regards,
> >
> > --
> > Anthony Ramine
> >
> > Le 17 mai 2013 à 10:55, Masatake Daimon a écrit :
> >
> >> Hello,
> >>
> >> Compiling the following module makes the compiler crash. I'm using
> >> R16B.
> >>
> >> ===== test.erl =====
> >> -module(test).
> >> -compile(inline).
> >> -compile(inline_list_funcs).
> >> -export([foo/0]).
> >>
> >> foo() ->
> >>   lists:map(fun bar/1, [1]).
> >>
> >> bar(X) -> X.
> >>
> >> ===== the crash ====
> >> % erlc test.erl
> >> test: function '-foo/0-lists^map/1-0-'/1+15:
> >> Internal consistency check failed - please report this bug.
> >> Instruction: {move,{x,0},{yy,0}}
> >> Error:       {invalid_store,{yy,0},term}:
> >>
> >>
> >> Note that the problem disappears with any of these changes:
> >>
> >> * Commenting out "-compile(inline)."
> >> * Commenting out "-compile(inline_list_funcs)."
> >> * Changing the definition of foo/0 to:
> >>     foo() ->
> >>         lists:map(fun bar/1, []).   % [] instead of [1]
> >> * Changing the definition of foo/0 to:
> >>     foo() ->
> >>         lists:map(fun (A) -> bar(A) end, [1]).
> >>
> >> Regards,
> >> --
> >> 大門 正岳 <daimon@REDACTED>
> >> _______________________________________________
> >> erlang-bugs mailing list
> >> erlang-bugs@REDACTED
> >> http://erlang.org/mailman/listinfo/erlang-bugs
> >
>
> _______________________________________________
> erlang-bugs mailing list
> erlang-bugs@REDACTED
> http://erlang.org/mailman/listinfo/erlang-bugs
>



-- 
Björn Gustavsson, Erlang/OTP, Ericsson AB
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