[Bug c++/68288] botched floating-point UDL

[solodon at mail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68288

Yuriy Solodkyy  changed:

   What|Removed |Added

 CC||solodon at mail dot com

--- Comment #3 from Yuriy Solodkyy  ---
This seems to be a genuine bug in GCC, not specific to floating-point UDL. It
is still present in GCC 10.2. ICC barks on it as well, but Clang and MSVC
accepts. 

Consider:

struct s_points { unsigned long long value; };
inline s_points operator"" _sp(unsigned long long v) { return {v}; }

s_points operator+(s_points, s_points);
s_points operator-(s_points, s_points);

s_points foo(s_points p)
{
return p-42_sp+1_sp; // Put space before + here and GCC will accept the
code
}

I get the following error on return statement line above:

:9:14: error: unable to find numeric literal operator
'operator""_sp+1_sp'

9 | return p-42_sp+1_sp;
  |  ^~

Since ud-suffix is just an identifier in the grammar, it should not grab +
while parsing, which according to error is what it seems to be doing.

Here is this snippet on Compiler Explorer: https://godbolt.org/z/4bfs6P

[Bug c++/68288] botched floating-point UDL

[solodon at mail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68288

--- Comment #4 from Yuriy Solodkyy  ---
P.S. I added my previous example to this bug as they seemed to be related, feel
free to split it into a separate bug if they are not.

P.P.S. Change that return expression to 42_sp-p and the parser seems to think
the entire _sp-p is a UDL suffix:

:9:12: error: unable to find numeric literal operator 'operator""_sp-p'

9 | return 42_sp-p;
  |^~~