Re: Extern variables in *.c files (maintainers pls read this)

Date: Thu Jan 03 2002 - 19:28:55 EST

> So, you have a choice:
> 1. Enable -fno-common
> - detect variables that should be marked static which aren't
> - don't detect size differences
> 2. Disable -fno-common
> - don't detect variables that should be marked static
> - detect size differences as long as the variables aren't marked extern
> As soon as someone has int foo in one file, and extern char foo in another,
> you've lost no matter which option you take.
> The header file approach is the most reliable (and imho correct) method to
> solve this problem.

And this method is traditional for C. We have struct declarations and fn
propotypes in *.h, we should place extern vars there too. Always.

If you are a kernel subsystem or driver maintainer, you may wish to check
whether *your* part of kernel has any extern variable defs. Just run this
hunter script in top dir of kernel source:

function do_grep() {
    for i in $dir/$*; do
        if ! test -d "$i"; then
            if test -e "$i"; then
                grep -E "$pattern" "$i" /dev/null
    for i in $dir/*; do
        if test -d "$i"; then
            do_grep "$pattern" "$i" $*

do_grep 'extern [^()]*;' . "*.c" 2>&1 | tee ../extern.log

Output is not attached here, it's too big: ~100 KB, ~1500 lines for 2.5.1-pre8

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This archive was generated by hypermail 2b29 : Mon Jan 07 2002 - 21:00:22 EST