[Bug c/61162] New: possibly bad error location with -Wc++-compat

["tromey at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61162

            Bug ID: 61162
           Summary: possibly bad error location with -Wc++-compat
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: tromey at gcc dot gnu.org

Consider this source:

enum e { ZERO = 0, ONE };

enum e e_val;

void f(void)
{
  e_val = 0;
}


Compile with -Wc++-compat:

bapiya. gcc -Wc++-compat --syntax-only r.c
r.c: In function ‘f’:
r.c:7:3: warning: enum conversion in assignment is invalid in C++
[-Wc++-compat]
   e_val = 0;
   ^


I think perhaps using the location of the "=" would be preferable.
>From gcc-bugs-return-451393-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Tue May 13 03:51:22 2014
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From: "hstong at ca dot ibm.com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/61163] New: Placement arguments shared between allocation and deallocation even when copies prohibited
Date: Tue, 13 May 2014 03:51:00 -0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?ida163

            Bug ID: 61163
           Summary: Placement arguments shared between allocation and
                    deallocation even when copies prohibited
           Product: gcc
           Version: 4.8.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hstong at ca dot ibm.com

In N3290 subclause 5.3.4 [expr.new] paragraph 21, the leeway to reuse the same
copy of the initialized parameter for both the call to the allocation function
and the call to the deallocation function is prefaced with "[i]f the
implementation is allowed to make a copy".
Since, in the case below, list initialization does not involve copying
following the call to the converting constructor, there is no copying to speak
of and the leeway is not given.
GCC performs the reuse anyway.

### SOURCE:> cat gccListInitNewPlacement.cc
extern "C" int printf(const char *, ...);

struct A {
   A(const A &) = delete;
   A(A &&) = delete;

   A(int) : x(0) { printf("%s\n", __PRETTY_FUNCTION__); }
   ~A() { printf("%s\n", __PRETTY_FUNCTION__); }

   int x;
};

struct B {
   static void *operator new(decltype(sizeof(0)) sz, A a) {
      printf("%d %s\n", a.x++, __PRETTY_FUNCTION__);
      return ::operator new(sz);
   }

   static void operator delete(void *ptr, A a) {
      printf("%d %s\n", a.x++, __PRETTY_FUNCTION__);
      return ::operator delete(ptr);
   }

   B() { throw 0; }
};

int main() {
   try { new ({0}) B; } catch(...) { }
}


### COMPILER INVOCATION:> g++ -std=c++11 -pedantic-errors -Wall -Wextra
gccListInitNewPlacement.cc -o gccListInitNewPlacement


### OUTPUT FROM RESULTING BINARY:> ./gccListInitNewPlacement
A::A(int)
0 static void* B::operator new(long unsigned int, A)
1 static void B::operator delete(void*, A)
A::~A()


### EXPECTED OUTPUT:
A::A(int)
0 static void* B::operator new(long unsigned int, A)
A::A(int)
0 static void B::operator delete(void*, A)
A::~A()
A::~A()


### VERSION INFO:> g++ -v
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-pc-cygwin/4.8.2/lto-wrapper.exe
Target: x86_64-pc-cygwin
Configured with:
/cygdrive/i/szsz/tmpp/cygwin64/gcc/gcc-4.8.2-3/src/gcc-4.8.2/configure
--srcdir=/cygdrive/i/szsz/tmpp/cygwin64/gcc/gcc-4.8.2-3/src/gcc-4.8.2
--prefix=/usr --exec-prefix=/usr --bindir=/usr/bin --sbindir=/usr/sbin
--libexecdir=/usr/libexec --datadir=/usr/share --localstatedir=/var
--sysconfdir=/etc --libdir=/usr/lib --datarootdir=/usr/share
--docdir=/usr/share/doc/gcc --htmldir=/usr/share/doc/gcc/html -C
--build=x86_64-pc-cygwin --host=x86_64-pc-cygwin --target=x86_64-pc-cygwin
--without-libiconv-prefix --without-libintl-prefix --enable-shared
--enable-shared-libgcc --enable-static --enable-version-specific-runtime-libs
--enable-bootstrap --disable-__cxa_atexit --with-dwarf2 --with-tune=generic
--enable-languages­a,c,c++,fortran,lto,objc,obj-c++ --enable-graphite
--enable-threads=posix --enable-libatomic --enable-libgomp --disable-libitm
--enable-libquadmath --enable-libquadmath-support --enable-libssp
--enable-libada --enable-libgcj-sublibs --disable-java-awt --disable-symvers
--with-ecj-jar=/usr/share/java/ecj.jar --with-gnu-ld --with-gnu-as
--with-cloog-include=/usr/include/cloog-isl --without-libiconv-prefix
--without-libintl-prefix --with-system-zlib --libexecdir=/usr/lib
Thread model: posix
gcc version 4.8.2 (GCC)