Re: Wanted: if new returns NULL, don't run constructor

[Marc Espie <espie at quatramaran dot ens dot fr>]

It does seem to work in recent egcs on sparc, at least.
Take the following code:
//------------------------------
#include <new>

struct A
	{
	int a;
	A();
	};

A::A()
	{
	a = 5;
	}

void f()
	{
	struct A *p;

	p = new (nothrow) A;
	}

Run it thru g++ -Wall -S -fno-handle-exceptions. This yields:
	.file	"a.C"
gcc2_compiled.:
.section	".rodata"
	.align 8
.LLC0:
	.asciz	"bad_alloc"
.section	".text"
	.align 4
	.global __1A
	.type	 __1A,#function
	.proc	0110
__1A:
	!#PROLOGUE# 0
	save	%sp, -112, %sp
	!#PROLOGUE# 1
	mov	%i0, %o0
	mov	5, %o1
	st	%o1, [%o0]
.LL16:
	mov	%o0, %i0
	b	.LL15
	 nop
.LL15:
	ret
	restore
.LLfe1:
	.size	 __1A,.LLfe1-__1A
	.align 4
	.global f__Fv
	.type	 f__Fv,#function
	.proc	020
f__Fv:
	!#PROLOGUE# 0
	save	%sp, -120, %sp
	!#PROLOGUE# 1
	mov	4, %o0
	sethi	%hi(nothrow), %o2
	or	%o2, %lo(nothrow), %o1
	call	__nw__FUiRC9nothrow_t, 0
	 nop
	mov	%o0, %l0
	cmp	%l0, 0
	be	.LL18
	nop
	mov	%l0, %o0
	call	__1A, 0
	 nop
	st	%o0, [%fp-20]
	b	.LL19
	 nop
.LL18:
	st	%l0, [%fp-20]
.LL19:
.LL17:
	ret
	restore
.LLfe2:
	.size	 f__Fv,.LLfe2-f__Fv
	.ident	"GCC: (GNU) egcs-2.93.05 19990207 (gcc2 ss-980929 experimental)"


Notice the
	mov	%o0, %l0
	cmp	%l0, 0
	be	.LL18
sequence right after the call to new (nothrow) and right before the call
to A's constructor. What are you missing there ? The pointer checking code
is emitted at new's site, not within the constructor. Do you have a
symptomatic case where more is needed ?