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Diffstat (limited to 'docs/building/building.sgml')
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diff --git a/docs/building/building.sgml b/docs/building/building.sgml index 0975985c27..fc342d04ee 100644 --- a/docs/building/building.sgml +++ b/docs/building/building.sgml @@ -4129,6 +4129,36 @@ that Haskell programs compiled by GHC-cygwin can import the (Haskell) Posix libr </para> </sect3> +<sect3><title>HOST_OS vs TARGET_OS</title> + +<para> +In the source code you'll find various ifdefs looking like: +<programlisting> + #ifdef mingw32_HOST_OS + ...blah blah... + #endif +</programlisting> +and +<programlisting> + #ifdef mingw32_TARGET_OS + ...blah blah... + #endif +</programlisting> +These macros are set by the configure script (via the file config.h). +Which is which? The criterion is this. In the ifdefs in GHC's source code: +<itemizedlist> + <listitem> <para> + The "host" system is the one on which GHC itself will be run. + </para> </listitem> + <listitem> <para> + The "target" system is the one for which the program compiled by GHC will be run. + </para> </listitem> +</itemizedlist> +For a stage-2 compiler, in which GHCi is available, the "host" and "target" systems must be the same. +So then it doesn't really matter whether you use the HOST_OS or TARGET_OS cpp macros. +</para> +</sect3> + <sect3><title>Summary</title> <para>Notice that "GHC-mingw" means "GHC that <emphasis>targets</emphasis> MinGW". It says nothing about |