Const Error

[James Tabor]

Hi!

i386-mingw32-gcc -D_WIN32_IE=0x0600 -D_WIN32_WINNT=0x0501 -I./include -DUNICODE -D_UNICODE 
-D__REACTOS__ -D__USE_W32API -D_HIDPI_ -D_HIDPI_NO_FUNCTION_MACROS_ -Wall -Werror -fno-builtin -I. 
-I../../include -I../../w32api/include -pipe -march=i486 -D_M_IX86 -g -c hid.c -o hid.o
hid.c: In function `HidD_Hello':
hid.c:374: warning: duplicate `const'
make: *** [hid.o] Error 1

const PCHAR const HelloString = "Hello\n";
               ^
               | is that right?

I'm back online!
James

[Mike Nordell]

James Tabor wrote:
> const PCHAR const HelloString = "Hello\n";
>                ^
>                | is that right?

No.

Assuming PCHAR is just a (IMO basically useless) "typedef char* PCHAR;",
then "const PCHAR" would mean nothing, since you can't modify the
cv-qualification of a typedef like this (cv is C and C++ standard lingo,
meaning "const/volatile"). This is one of the reasons such stupid typedefs
are bad - the only way to make them point to a const object is by adding yet
_another_ typedef: "typedef const char* PCCHAR;" (or CPCHAR if you're into
that kind of naming :-) ), or by literally using the real type the typedef
refers to.

I suspect the well-meaning intention, but not equally informed wrt
cv-qualification and typedefs, was:

const char* HelloString const = ...

but why anyone would do something like that instead of just

const char HelloString[] = ...

or if wanting to make the code more obscure, harder to understand and
therefore less maintainable

LPCSTR const HelloString = ...

I don't understand.

--
/Mike

[Thomas Weidenmueller]

James Tabor wrote:
> Hi!
>
> i386-mingw32-gcc -D_WIN32_IE=0x0600 -D_WIN32_WINNT=0x0501 -I./include 
> -DUNICODE -D_UNICODE -D__REACTOS__ -D__USE_W32API -D_HIDPI_ 
> -D_HIDPI_NO_FUNCTION_MACROS_ -Wall -Werror -fno-builtin -I. 
> -I../../include -I../../w32api/include -pipe -march=i486 -D_M_IX86 -g 
> -c hid.c -o hid.o
> hid.c: In function `HidD_Hello':
> hid.c:374: warning: duplicate `const'
> make: *** [hid.o] Error 1
>
> const PCHAR const HelloString = "Hello\n";
>               ^
>               | is that right?
>
> I'm back online!
> James
> _______________________________________________
> Ros-dev mailing list
> [e-mail]
> http://reactos.com:8080/mailman/listinfo/ros-dev

it should be right - it is a constant pointer to constant data. But i'm 
not 100% sure if it's just a c++ feature.

Best Regards
Thomas