[Buildroot] ccache problem when compiling with different toolchains in different projects

[Danomi Manchego]

On Mon, Apr 22, 2013 at 1:59 AM, Arnout Vandecappelle <arnout at mind.be>wrote:

> On 20/04/13 18:08, Danomi Manchego wrote:
>
>> On Fri, Apr 19, 2013 at 7:41 PM, Arnout Vandecappelle <arnout at mind.be
>> <mailto:arnout at mind.be>> wrote:
>>
>>         Then, the effects of all the
>>         hidden variables are in some way accounted for without grepping
>>         for them
>>         in the .config.
>>
>>
>>       Not entirely. Many toolchain options affect the C library, not the
>>     compiler. A change in these options may not affect the gcc binary
>>     itself. Even a gcc configuration option may not change the gcc
>>     binary, because most of gcc is in cc1 and libgcc.a. But it's still an
>>     improvement over previous proposals.
>>
>>
>> Arnout, I'm wavering on this.
>>
>> At work, we only use external toolchains (downloaded or pre-installed),
>> so using the gcc -v output and the md5sum of the compiler/wrapper
>> provided to ccache is perfect for our projects, because
>> these discriminators capture everything.  But if toolchain configuration
>> options in the general case (for everyone else) cannot be simply captured
>> (without doing lots of variable renaming as you mentioned earlier),
>>
>
>  Actually, after thinking a bit harder about it: the following should work:
>
> sed -n '/^# Toolchain/,/^# System configuration/' $(BUILDROOT_CONFIG) \
>         | md5sum -
>
>  So there's no need to rename stuff or anything.


That would also use the GDB and ECLIPSE lines too.  But then, if it
accounts for everything outside of the "%compiler% -v" info (wrappers,
C-library), then it's worth it.

I suppose that we could drop the these lines with an inverse grep:

sed -n '/^# Toolchain/,/^# System configuration/p' .config | \
    grep -v -e '^#' -e GDG -e ECLIPSE | \
    md5sum

Too much?
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