info functions bug?

info functions bug?

[Andrew STUBBS]

Hi,

There seems to be a problem with 'info functions'. It prints the return 
type of template functions twice.

Here's some example code:


template <typename TT>
TT& max(TT& a, TT& b)
{
   return (a>b ? a : b);
}

int
main()
{
   int a = 1, b = 2;
   float c = 1.1, d = 2.2;
   max(a,b);
   max(c,d);
   return 0;
}


This is correctly interpreted by nm and c++filt as follows:


$ nm -C a.out | grep max
88001878 W float& max<float>(float&, float&)
88001830 W int& max<int>(int&, int&)


But GDB gives a slightly different name:


(gdb) info functions max
All functions matching regular expression "max":

File t.cpp:
float &float& max<float>(float&, float&);
int &int& max<int>(int&, int&);


This name is not accepted when setting a breakpoint, but remove the 
extra return type and all is well:


(gdb) b float &float& max<float>(float&, float&)
Function "float &float& max<float>(float&, float&)" not defined.
(gdb) b float& max<float>(float&, float&)
Breakpoint 2 at 0x8800188a: file t.cpp, line 4.


(Irritatingly, 'break max' doesn't work - it doesn't even prompt.)

Presumably this is not the intended output for this type of function?

Andrew

Re: info functions bug?

[Daniel Jacobowitz]

On Tue, Aug 21, 2007 at 12:31:53PM +0100, Andrew STUBBS wrote:
> Hi,
> 
> There seems to be a problem with 'info functions'. It prints the return type of 
> template functions twice.

Yes, this is a known problem with handling of template functions.
It's related to all the things we were talking about yesterday.
It comes from the demangled name differences: template mangled names
include the return type, non-template C++ mangled names do not.

My patches (rather bit-rotten now I'm afraid) to avoid relying on
mangled names improved the situation a bit.  I don't think there's
an easier way though :-(

-- 
Daniel Jacobowitz
CodeSourcery