Re: GDB syntax error if class members overlap C++ header file names

Simon Marchi
2018-02-13T15:52:29Z

On 2018-02-13 10:37, Paul Smith wrote:
> Has anyone had any thoughts about
> https://sourceware.org/bugzilla/show_bug.cgi?id=22231
>
> This is a really unfortunate bug, because there are so many useful
> symbol names which are also C++ header files! Just ran into this again
> with "queue".
>
> Quoted from the bug:
>
>> I've discovered that if you compile a C++ program with -ggdb3 (not
>> -g) then any C++ header file (sans .h extension) that is included
>> will cause a syntax error whenever you try to print that name. Also,
>> if you try to print a class member with that name it will also fail.
>>
>> I've tried this with GDB 7.7, 7.11, and 8.0 and all behave the same
>> way. I've used both GCC 6.2 and 6.3.
>
> And I've tried 8.1 as well just to be sure; same behavior:
>
>> (gdb) p memory
>> A syntax error in expression, near `'.
>>
>> This will be the same for any other C++ (without .h) header that is
>> included. If you change to #include <memory.h> then you won't get
>> this error (you'll get 'No symbole "memory" in current context.' as
>> expected).
>>
>> If you create a local variable or an auto variable named "memory",
>> GDB will print it properly.
>>
>> However, if you have a class member named "memory", GDB again won't
>> parse it;
>
>> (gdb) p foo.memory
>> A syntax error in expression, near `'.
>>
>>
>>
>> If you enable debugging you'll see:
>>
>> (gdb) set debug parser on
>> (gdb) p memory
>> Starting parse
>> Entering state 0
>> Reading a token: Next token is token FILENAME (bval<0x1a66ac0>)
>> Shifting token FILENAME (bval<0x1a66ac0>)
>> Entering state 47
>> Reducing stack by rule 107 (line 877):
>> $1 = token FILENAME (bval<0x1a66ac0>)
>> -> $$ = nterm block ()
>> Stack now 0
>> Entering state 57
>> Reading a token: Now at end of input.
>> A syntax error in expression, near `'.

Hi Paul,

This looks like an issue that has been fixed recently, but it's not in
8.1, only master.

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=commit;h=59498c305e6f1db2a1ed8d44cb58f0d24ec092fe

Can you verify if it works for you?

Simon