[PATCH] fix openssl headers conflicting with custom SHA1 implementations

On ARM I have the following compilation errors:

    CC fast-import.o
In file included from cache.h:8,
                 from builtin.h:6,
                 from fast-import.c:142:
arm/sha1.h:14: error: conflicting types for 'SHA_CTX'
/usr/include/openssl/sha.h:105: error: previous declaration of 'SHA_CTX' was here
arm/sha1.h:16: error: conflicting types for 'SHA1_Init'
/usr/include/openssl/sha.h:115: error: previous declaration of 'SHA1_Init' was here
arm/sha1.h:17: error: conflicting types for 'SHA1_Update'
/usr/include/openssl/sha.h:116: error: previous declaration of 'SHA1_Update' was here
arm/sha1.h:18: error: conflicting types for 'SHA1_Final'
/usr/include/openssl/sha.h:117: error: previous declaration of 'SHA1_Final' was here
make: *** [fast-import.o] Error 1

This is because openssl header files are always included in 
git-compat-util.h since commit 684ec6c63c whenever NO_OPENSSL is not 
set, which somehow brings in <openssl/sha1.h> clashing with the custom 
ARM version.  Compilation of git is probably broken on PPC too for the 
same reason.

Turns out that the only file requiring openssl/ssl.h and openssl/err.h 
is imap-send.c.  But only moving those problematic includes there 
doesn't solve the issue as it also includes cache.h which brings in the 
conflicting header.  So also conditionally including SHA1_HEADER allows 
for not including it when compiling imap-send.c.

Signed-off-by: Nicolas Pitre <redacted>

---

This is a bit ugly but given the rat nest of system includes we have I 
don't know how to solve this any better.

diff --git a/Makefile b/Makefile
index 3c0664a..a0f86dd 100644
--- a/Makefile
+++ b/Makefile

@@ -1242,6 +1242,9 @@ endif
 git-%$X: %.o $(GITLIBS)
 	$(QUIET_LINK)$(CC) $(ALL_CFLAGS) -o $@ $(ALL_LDFLAGS) $(filter %.o,$^) $(LIBS)
 
+imap-send.o: imap-send.c GIT-CFLAGS
+	$(QUIET_CC)$(CC) -o $*.o -c $(ALL_CFLAGS) -USHA1_HEADER $<
+
 git-imap-send$X: imap-send.o $(GITLIBS)
 	$(QUIET_LINK)$(CC) $(ALL_CFLAGS) -o $@ $(ALL_LDFLAGS) $(filter %.o,$^) \
 		$(LIBS) $(OPENSSL_LINK) $(OPENSSL_LIBSSL)

diff --git a/cache.h b/cache.h
index de8c2b6..d93e086 100644
--- a/cache.h
+++ b/cache.h

@@ -5,7 +5,10 @@
 #include "strbuf.h"
 #include "hash.h"
 
+#ifdef SHA1_HEADER
 #include SHA1_HEADER
+#endif
+
 #include <zlib.h>
 
 #if defined(NO_DEFLATE_BOUND) || ZLIB_VERNUM < 0x1200

diff --git a/git-compat-util.h b/git-compat-util.h
index db2836f..044f62b 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h

@@ -99,11 +99,6 @@
 #include <iconv.h>
 #endif
 
-#ifndef NO_OPENSSL
-#include <openssl/ssl.h>
-#include <openssl/err.h>
-#endif
-
 /* On most systems <limits.h> would have given us this, but
  * not on some systems (e.g. GNU/Hurd).
  */

diff --git a/imap-send.c b/imap-send.c
index af7e08c..01f1c9a 100644
--- a/imap-send.c
+++ b/imap-send.c

@@ -22,11 +22,15 @@
  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */
 
-#include "cache.h"
 #ifdef NO_OPENSSL
 typedef void *SSL;
+#else
+#include <openssl/ssl.h>
+#include <openssl/err.h>
 #endif
 
+#include "cache.h"
+
 struct store_conf {
 	char *name;
 	const char *path; /* should this be here? its interpretation is driver-specific */

Nicolas