[Tinyos-devel] The infamous $ in identifiers ...

[Aurélien Francillon]

Hi,
since a quite long time (ever ?) tinyos/nesc uses the "$" sign in
identifiers for translating modules names + function/variable name into
one unique label, this is mostly transparent to the developer as this is
seen only in the C file generated by nesc and sent to gcc, but :
- it requires a patch to binutils  and it does not looks like it's going
to be included in default binutils. The effort [1] didn't get very far
and a patch would be needed for each architecture avr/msp/arm ?
- if it get in one day it's going to be for future versions only not
likely back ported to older versions,
- default compiler is therefore not working with default tinyos tree out
of the box and build dies with thousands of obscure messages from the
assembler,
- packages maintainers of linux distributions/toolchain scripts usually
like to have the less possible number of patches added to the vanilla
package, and i don't know any other "user" of "$ in identifiers" than
tinyos ?
- gdb does not like it, the $ breaks label auto completion in terminal
mode, and IIRC you need to quote identifiers,
- I personally find it ugly ;) and it bites me form time to time,
"hopefully" so many times that I recognize it immediately now ;), but
for new users to tinyos this might be hard to debug, especially
considering the quite large avr community, lots of them may have skipped
the install step of the patched binutils if they already have it,
- support is there in some makefiles (at least avr.rules and msp.rules)
to use "__" instead, this works very well for me since a few months
without problems,
- is it compliant with the C standard ?
- is see no drawback ? Is there any ? Well, it probably breaks if
someone is using "__" in a variable name or module name in a .nc file.
Could nesc check for this and display a nice informative message ?

As a release is going out soon it's probably too late in
the testing phase to have this in ? Although the change should not
break anything and stripped binaries should be exactly the same...
Could this be discussed for the next one ?

Cheers
Aurélien

[1] http://sourceware.org/ml/binutils/2007-04/msg00161.html