compile and syntax_tools disagree

As far as I understand, The ERTS User's Guide says that
you'll need two
layers of lists to represent a guard sequence.

syntax_tools still accepts the older format of guards
(before semicolons
in guards were introduced), so that it can still be used for
the abstract
format in old Beam files.

So as I see, there is no bug.

/Björn

"Ulf Wiger (TN/EAB)" <ulf.wigerericsson.com> writes:

> I'm getting a bit cross-eyed, but this has got to be a
bug *somewhere*:
> 
> 12> M =
[{attribute,1,module,m},{attribute,1,export,[{foo,1}]}|Fs]
++
> [{eof,1}]. 
> [{attribute,1,module,m},
>  {attribute,1,export,[{foo,1}]},
>  {function,1,
>            foo,
>            1,
>            [{clause,1,
>                     [{var,1,'R'}],
>                    
[{op,1,'==',{var,1,'R'},{integer,1,1}}],
>                     [{atom,1,true}]}]},
>  {eof,1}]
> 13> compile:forms(M).
> .:none: internal error in expand_module;
> crash reason: {function_clause,
>                   [{erl_expand_records,
>                        guard_tests1,
>                       
[{op,1,'==',{var,1,'R'},{integer,1,1}},
> ...
>                    {erl_expand_records,guard_tests,2},
>                    {erl_expand_records,guard,2},
>                    {erl_expand_records,clauses,2},
>                    {erl_expand_records,forms,2},
>                    {erl_expand_records,forms,2},
>                    {erl_expand_records,module,2},
>                    {sys_pre_expand,module,2}]}
> error
> 14> M1 =
[{attribute,1,module,m},{attribute,1,export,[{foo,1}]}|Fs1]
++
> [{eof,1}].
> [{attribute,1,module,m},
>  {attribute,1,export,[{foo,1}]},
>  {function,1,
>            foo,
>            1,
>            [{clause,1,
>                     [{var,1,'R'}],
>                    
[[{op,1,'==',{var,1,'R'},{integer,1,1}}]],
>                     [{atom,1,true}]}]},
>  {eof,1}]
> 15> compile:forms(M1).
> {ok,m,
>  
>
<<70,79,82,49,0,0,1,184,66,69,65,77,65,116,111,109,0,0
,0,50,0,0,0,6,1,10
> 9,
>       ...>>}
> 
> When pretty-printing the two form lists using
erl_prettypr:format/2, 
> you get the same output, and according to the ERTS
User's Guide,
> the two guard representations should be equivalent. A
list of lists
> in the Guard represents a disjunction, and a list of
Guard expressions
> represents a conjunction. In this case, there's only
one guard expr.
> 
> 6> erl_prettypr:format(erl_syntax:form_list(Fs)).
> "foo(R) when R == 1 -> true."      
> 6> erl_prettypr:format(erl_syntax:form_list(Fs1)).
> "foo(R) when R == 1 -> true."      
> 
> It seems to me as if the bug is in the compiler
(version 4.4.3).
> 
> Forgive me for not diving into the compiler source code
to verify
> this claim. Time to put the kids to sleep.
> 
> BR,
> Ulf W
> _______________________________________________
> erlang-bugs mailing list
> erlang-bugserlang.org
> ht
tp://www.erlang.org/mailman/listinfo/erlang-bugs

-- 
Björn Gustavsson, Erlang/OTP, Ericsson AB

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compile and syntax_tools disagree

Thread: compile and syntax_tools disagree