Nesting m4 macros

[Matthias Wichtlhuber]

Hi list,

this is my first post here, so I hope this is the right list and I am 
not violating the netiquette.

I'm a complete autoconf newbie. For a small project I want to test, 
whether the cuda NVCC compiler's version is appropriate. The version is 
appropriate, when the output of the command "nvcc --version" contains 
the string "release 3.0". If not, I want to print a warning.

AS_IF([test m4_index([m4_esyscmd([nvcc --version])], [release 3.0]) -eq 
-1],[
                AC_MSG_WARN([NVCC compiler version is NOT 3.0!])
        ])

Unfortunately the condition in the AS_IF always evaluates to true, so 
the warning is always printed. M4 seems to treat the esyscmd as a 
string. I have tried every thinkable way of quoting this. Any ideas?

Thanks,

Matthias