Re: [Qemu-devel] [PATCH] scripts: add a guard macro in generated .h files

[Aurelien Jarno <aurelien@aurel32.net>]

On Mon, Feb 07, 2011 at 04:21:40PM +0100, Tristan Gingold wrote:
> To avoid redefinition warnings.
> 
> Signed-off-by: Tristan Gingold <gingold@adacore.com>
> ---
>  rules.mak             |    2 +-
>  scripts/create_config |   12 ++++++++++++
>  2 files changed, 13 insertions(+), 1 deletions(-)
> 
> diff --git a/rules.mak b/rules.mak
> index ed59c9e..fb38f96 100644
> --- a/rules.mak
> +++ b/rules.mak
> @@ -57,7 +57,7 @@ find-in-path = $(if $(find-string /, $1), \
>  	@test -f $@ || cp $< $@
>  
>  %.h-timestamp: %.mak
> -	$(call quiet-command, sh $(SRC_PATH)/scripts/create_config < $< > $@, "  GEN   $*.h")
> +	$(call quiet-command, sh $(SRC_PATH)/scripts/create_config $* < $< > $@, "  GEN   $*.h")
>  	@cmp $@ $*.h >/dev/null 2>&1 || cp $@ $*.h
>  
>  # will delete the target of a rule if commands exit with a nonzero exit status
> diff --git a/scripts/create_config b/scripts/create_config
> index 0098e68..0302eab 100755
> --- a/scripts/create_config
> +++ b/scripts/create_config
> @@ -1,7 +1,17 @@
>  #!/bin/sh
>  
> +if [ $# -ne 1 ]; then
> +  echo "Usage: $0 filename" 2>&1
> +  exit 1
> +fi
> +
> +cond_macro=`echo $1 | tr a-z- A-Z_`_H
> +
>  echo "/* Automatically generated by create_config - do not modify */"
>  
> +echo "#ifndef $cond_macro"
> +echo "#define $cond_macro"
> +
>  while read line; do
>  
>  case $line in
> @@ -101,3 +111,5 @@ case $line in
>  esac
>  
>  done # read
> +
> +echo "#endif /* $cond_macro */"

config-host.h only contains #define entries, and GCC doesn't choke when
as long as the definitions are the same. What is the use case of this
patch? 

-- 
Aurelien Jarno                          GPG: 1024D/F1BCDB73
aurelien@aurel32.net                 http://www.aurel32.net