Re: Latest EMACS on BZR trunk does not compile with MinGW

[Óscar Fuentes]

Eli Zaretskii <address@hidden> writes:

>> Why not test if the preprocessor defines __MINGW32__?
>
> How will you call the compiler?  Its exact name and directory isn't
> known until much later in the script.

The build failure came from the configure script deciding something
about dup2 based on MSYSTEM. That sounds wrong to me: the
characteristics of a function are supposed to be decided based on
specific tests. That means that when dup2 is probed by the configure
script the test code should detect that we are using the MS C runtime
and return an specific code.

Is MSYSTEM relevant for anything that must be deciced before we can
invoke the compiler?

> Perhaps we should only worry about detecting that MSYSTEM isn't set
> when it should be.  For that, we can wait until the script figures out
> how to invoke the compiler, and _then_ see if the preprocessor defines
> __MINGW32__.  If it does, but MSYSTEM is not set, we display an error
> message and exit.  I think this should be enough; valid MSYS
> installation should read /etc/profile and then they will have MSYSTEM
> defined.

Something like this would be good too, but please note that MSYSTEM can
be defined with a wrong value. My build failure came from starting MSYS2
with the wrong script, the one that defines MSYSTEM to "MSYS".