Generate the C main() function when linking a binary (fixes #5373)

Rather than have main() be statically compiled as part of the RTS, we
now generate it into the tiny C file that we compile when linking a
binary.

The main motivation is that we want to pass the settings for the
-rtsotps and -with-rtsopts flags into the RTS, rather than relying on
fragile linking semantics to override the defaults, which don't work
with DLLs on Windows (#5373).  In order to do this, we need to extend
the API for initialising the RTS, so now we have:

void hs_init_ghc (int *argc, char **argv[],   // program arguments
                  RtsConfig rts_config);      // RTS configuration

hs_init_ghc() can optionally be used instead of hs_init(), and allows
passing in configuration options for the RTS.  RtsConfig is a struct,
which currently has two fields:

typedef struct {
    RtsOptsEnabledEnum rts_opts_enabled;
    const char *rts_opts;
} RtsConfig;

but might have more in the future.  There is a default value for the
struct, defaultRtsConfig, the idea being that you start with this and
override individual fields as necessary.

In fact, main() was in a separate static library, libHSrtsmain.a.
That's now gone.

1 files changed, 1 insertions, 0 deletions

diff --git a/includes/Rts.h b/includes/Rts.h
index 91ec76d467..5caba59dbe 100644
--- a/includes/Rts.h
+++ b/includes/Rts.h
@@ -213,6 +213,7 @@ void _assertFail(const char *filename, unsigned int linenum)
 #include "rts/TTY.h"
 #include "rts/Utils.h"
 #include "rts/PrimFloat.h"
+#include "rts/Main.h"
 
 /* Misc stuff without a home */
 DLL_IMPORT_RTS extern char **prog_argv;	/* so we can get at these from Haskell */