Configuration: rework how dependency making is handled

Previously, we had dependency making pretty much hard coded in the
build file templates, with a bit of an exception for Unix family
platforms, where we had different cases depending on what dependency
making program was found.

With the Embarcadero C++ builder, a separate scheme appeared, with a
different logic.

This change merges the two, and introduces two config target
attributes:

    makedepcmd          The program to use, where this is relevant.
                        This replaces the earlier configuration
                        attribute 'makedepprog'.
    makedep_scheme      This is a keyword that can be used by build
                        files templates to produce different sorts of
                        commands, but most importantly, to pass as
                        argument to util/add-depend.pl, which uses
                        this keyword as a "producer" for the
                        dependency lines.

If the config target doesn't define the 'makedep_scheme' attribute,
Configure tries to figure it out by looking for GCC compatible
compilers or for the 'makedepend' command.

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
(Merged from https://github.com/openssl/openssl/pull/15006)

1 files changed, 19 insertions, 9 deletions

diff --git a/Configure b/Configure
index 6d0ffbf480..b068b60e66 100755
--- a/Configure
+++ b/Configure
@@ -1533,22 +1533,32 @@ unless ($disabled{asm}) {
 
 # Check for makedepend capabilities.
 if (!$disabled{makedepend}) {
-    if ($config{target} =~ /^(VC|BC|vms)-/) {
-        # For VC-, BC- and vms- targets, there's nothing more to do here.  The
-        # functionality is hard coded in the corresponding build files for
-        # cl/cpp32 (Windows) and CC/DECC (VMS).
+    # If the attribute makedep_scheme is defined, then we assume that the
+    # config target and its associated build file are programmed to deal
+    # with it.
+    # If makedep_scheme is undefined, we go looking for GCC compatible
+    # dependency making, and if that's not available, we try to fall back
+    # on 'makedepend'.
+    if ($target{makedep_scheme}) {
+        $config{makedep_scheme} = $target{makedep_scheme};
+        # If the makedepcmd attribute is defined, copy it.  If not, the
+        # build files will have to fend for themselves.
+        $config{makedepcmd} = $target{makedepcmd} if $target{makedepcmd};
     } elsif (($predefined_C{__GNUC__} // -1) >= 3
              && !($predefined_C{__APPLE_CC__} && !$predefined_C{__clang__})) {
         # We know that GNU C version 3 and up as well as all clang
         # versions support dependency generation, but Xcode did not
         # handle $cc -M before clang support (but claims __GNUC__ = 3)
-        $config{makedepprog} = "\$(CROSS_COMPILE)$config{CC}";
+        $config{makedep_scheme} = 'gcc';
     } else {
-        # In all other cases, we look for 'makedepend', and disable the
-        # capability if not found.
-        $config{makedepprog} = which('makedepend');
-        disable('unavailable', 'makedepend') unless $config{makedepprog};
+        # In all other cases, we look for 'makedepend', and set the
+        # makedep_scheme value if we found it.
+        $config{makedepcmd} = which('makedepend');
+        $config{makedep_scheme} = 'makedepend' if $config{makedepcmd};
     }
+
+    # If no depend scheme is set, we disable makedepend
+    disable('unavailable', 'makedepend') unless $config{makedep_scheme};
 }
 
 if (!$disabled{asm} && !$predefined_C{__MACH__} && $^O ne 'VMS') {