Re: Lists and aliasing (Re: Freeze on 27 February)

[Isaac Dupree]

On 02/22/2012 06:03 PM, Lennart Sorensen wrote:
> On Wed, Feb 22, 2012 at 05:50:37PM -0500, Lennart Sorensen wrote:
> > Now I get:
> >
> > gcc-4.6 -DHAVE_CONFIG_H -I. -I../../../grub-core -I..  -Wall -W -I../../../include 
> > -I../include  -DGRUB_MACHINE_EMU=1 -DGRUB_MACHINE=POWERPC_EMU -DGRUB_TARGET_CPU_POWERPC=1 
> > -m32 -DGRUB_FILE=\"normal/charset.c\" -I. -I../../../grub-core -I.. -I../../.. 
> > -I../../../include -I../include   -I../../../grub-core/lib/posix_wrap   -Os -Wall -W 
> > -Wshadow -Wold-style-declaration -Wold-style-definition -Wpointer-arith -Wundef -Wextra 
> > -Waddress -Warray-bounds -Wattributes -Wbuiltin-macro-redefined -Wcast-align 
> > -Wchar-subscripts -Wclobbered -Wcomment -Wcoverage-mismatch -Wdeprecated 
> > -Wdeprecated-declarations -Wdisabled-optimization -Wdiv-by-zero -Wempty-body 
> > -Wendif-labels -Wfloat-equal -Wformat-contains-nul -Wformat-extra-args -Wformat-security 
> > -Wformat-y2k -Wignored-qualifiers -Wimplicit -Wimplicit-function-declaration 
> > -Wimplicit-int -Winit-self -Wint-to-pointer-cast -Winvalid-pch 
> > -Wunsafe-loop-optimizations -Wlogical-op -Wmain -Wmissing-braces 
> > -Wmissing-field-initializers -Wmissing-fo
rmat-attribute -Wmissing-noreturn -W
> > mudflap -Wmultichar -Wnonnull -Woverflow -Wpacked-bitfield-compat -Wparentheses 
> > -Wpointer-arith -Wpointer-to-int-cast -Wreturn-type -Wsequence-point -Wshadow 
> > -Wsign-compare -Wstrict-aliasing -Wswitch -Wsync-nand -Wtrigraphs  
> > -Wtype-limits -Wundef -Wuninitialized -Wunknown-pragmas -Wunused 
> > -Wunused-function -Wunused-label -Wunused-parameter -Wunused-value  
> > -Wunused-variable -Wvariadic-macros -Wvolatile-register-var -Wwrite-strings 
> > -Wmissing-parameter-type -Wnested-externs -Wstrict-prototypes -Wpointer-sign -g 
> > -Wredundant-decls -Wmissing-prototypes -Wmissing-declarations 
> > -fno-dwarf2-cfi-asm -fno-asynchronous-unwind-tables -m32 -fno-stack-protector 
> > -Werror -Wno-trampolines -DUSE_ASCII_FAILBACK=1 -DHAVE_UNIFONT_WIDTHSPEC=1      
> >    -ffreestanding -fno-builtin -Wno-redundant-decls   -c -o 
> > normal/normal_module-charset.o `test -f 'normal/charset.c' || echo 
> > '../../../grub-core/'`normal/charset.c
> > ../../../grub-core/normal/charset.c: In function 'bidi_line_wrap':
> > ../../../grub-core/normal/charset.c:737:55: error: comparison between signed 
> > and unsigned integer expressions [-Werror=sign-compare]
> > cc1: all warnings being treated as errors
>
> For some reason the compiler thinks GRUB_INT_MIN which is defined as
> -0x80000000 is unsigned.

That's probably because "-0x80000000" *is* unsigned.

0x80000000 is an integer literal that does not fit into (32-bit) int but 
does fit into (32-bit) unsigned int.

The negation operator does not change the signedness of its operand's type.

It should probably be signed, e.g.
    #define GRUB_INT_MIN (-0x7fffffff - 1)