[Bug c++/95468] New: ICE in expression sfinae

[kab at acm dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95468

Bug ID: 95468
   Summary: ICE in expression sfinae
   Product: gcc
   Version: unknown
Status: UNCONFIRMED
  Severity: normal
  Priority: P3
 Component: c++
  Assignee: unassigned at gcc dot gnu.org
  Reporter: kab at acm dot org
  Target Milestone: ---

The code below gets ICE with gcc9.2 and gcc7.5 (the versions I have immediately
available to test with).

The error message is:
internal compiler error: unexpected expression '(bool)(true)' of kind cast_expr

To test:
g++ -c -std=c++11 ice-expr-sfinae.cpp

Strangely, using a namespace scope function template instead of a static member
function template works fine.  To demonstrate that, compile with
-DTRIGGER_ICE=0.

- ice-expr-sfinae.cpp -

#include 

#ifndef TRIGGER_ICE
#define TRIGGER_ICE 1
#endif

#if TRIGGER_ICE

struct slip {
  template static constexpr bool condition() { return C; }
};

template(), int>::type = 0>
static bool dispatch() { return true; }

bool test() {
  return dispatch();
}

#else

// No ICE if the condition function is at namespace scope.

template static constexpr bool noslip_condition() { return C; }

template(), int>::type =
0>
static bool dispatch() { return true; }

bool test() {
  return dispatch();
}

#endif

- end of file -

[Bug c++/95468] ICE in expression sfinae

[kab at acm dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95468

--- Comment #1 from kab at acm dot org ---
This was labeled as "ice-on-invalid-code".  Am I missing something?  I don't
see anything invalid here.

[Bug tree-optimization/96951] strncpy truncation warning does not recognize truncation check

[kab at acm dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96951

--- Comment #5 from kab at acm dot org ---
(In reply to Martin Sebor from comment #3)
> If in the code the test case was derived from the string
> member is not necessarily meant to be a string then declaring it with
> attribute nonstring avoids the warning:

In the original code the string is intended to be a nul-terminated string. 
Also, its in a struct from a system header, so not modifiable.

> As for memccpy...

memccpy isn't so portable (think Windows, which deprecates it, though under the
control of a macro).  The code from the discussion that led here could cope
with that, but that's not universally true.

[Bug c++/113760] gcc rejects valid empty-declaration in pedantic mode

[kab at acm dot org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113760

kab at acm dot org changed:

   What|Removed |Added

 CC||kab at acm dot org

--- Comment #5 from kab at acm dot org ---
(In reply to Andrew Pinski from comment #3)
> From JDK bug report:
> > It looks like it only removed
> > the warnings for empty declarations at namespace scope. I couldn't find
> > anything for other cases, including empty class member declarations.
> 
> Yes because the C++ defect report was only for `Spurious semicolons at
> namespace scope should be allowed`.  See
> https://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#569 .
> 
> 
> ```
> struct f
> {
>   int t;  ;
> };
> ```
> 
> Is not allowed by the C++ standard currently and is a GCC extension, maybe
> it should have a seperate flag to control that but I am not 100% sure.

It's C++14 that the openjdk currently cares about. C++14 added
"empty-declaration" to the syntax for "member-declaration".
C++14 9.2 [class.mem]
https://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#1693

The above "struct f" declaration warns with C++14 and -Wpedantic, but
shouldn't.

Tested with that struct as the only contents of "test.cpp" and this command
line for g++13.2.0:
g++ -c -Wpedantic -std=c++14 -o test.o test.cpp