Re: [lwip-users] about memory problem

[David Empson]

Simon Goldschmidtt <address@hidden> wrote:
> yueyue papa wrote:
> > > > ../../../../../lwip/src/core/init.c:156:4: #error "MEM_USE_POOLS
> > > > requires custom pools (MEMP_USE_CUSTOM_POOLS) to be enabled in your
> > > > lwipopts.h"
> > > >
> > > > I will understand If i see this, But my compiler (VC8) did not tell me
> > > > this error. I learned for lwIP from Wiki (Not from your referred
> > > > site), It is also not tell me to enable both macro.  :(
> That's strange because when I compile with VC8, I get this output when it
> comes to compiling init.c:
>
> init.c
> d:\dev\lwip\cvshead\lwip\src\include\lwip/memp.h(60) : error C2059:
> Syntaxfehler: ')'
> ..\..\..\..\lwip\src\core\init.c(156) : fatal error C1189: #error :
> "MEM_USE_POOLS requires custom pools (MEMP_USE_CUSTOM_POOLS) to be enabled
> in your lwipopts.h"

A very likely explanation for this is how the compiler has been configured
to handle errors, or how different compilers react to a particular error.

If it stops after any error, then the syntax error on line 60 of memp.h will
stop the compiler before it gets to the #error line in init.c, and you will
never see the explanation that the syntax error is caused by having
MEM_USE_POOLS=1 with MEMP_USE_CUSTOM_POOLS=0.

This is a strong argument in favour of the check being in a header file
(before getting to line 60 of memp.h) rather than in arbitrary source files.