[PATCH v4 19/19] Makefile & configure: make PCRE v2 the default PCRE implementation

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

Change the USE_LIBPCRE=YesPlease & --with-libpcre flags to the
Makefile & configure script, respectively, to mean use PCRE v2, not
PCRE v1.

The legacy library previously available via those options is still
available on request via USE_LIBPCRE1=YesPlease or
--with-libpcre1. The existing USE_LIBPCRE2=YesPlease & --with-libpcre2
still explicitly ask for v2.

The v2 PCRE is stable & end-user compatible, all this change does is
change the default. Someone building a new git is likely to also have
packaged PCRE v2 sometime in the last 2 years since it was released.
If not they can choose to use the legacy v2 library by making the
trivial s/USE_LIBPCRE/USE_LIBPCRE1/ change, or package up PCRE v2.

New releases of PCRE v2 are already faster than PCRE v1, and not only
is all significant development is happening on v2, but bugs in
reported against v1 have started getting WONTFIX'd asking users to
just upgrade to v2.

So it makes sense to give our downstream distributors a nudge to
switch over to it.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 Makefile     | 21 ++++++++++-----------
 configure.ac | 18 +++++++++---------
 2 files changed, 19 insertions(+), 20 deletions(-)

diff --git a/Makefile b/Makefile
index a792f206b9..42b09f9632 100644
--- a/Makefile
+++ b/Makefile
@@ -29,10 +29,10 @@ all::
 # Perl-compatible regular expressions instead of standard or extended
 # POSIX regular expressions.
 #
-# Currently USE_LIBPCRE is a synonym for USE_LIBPCRE1, define
-# USE_LIBPCRE2 instead if you'd like to use version 2 of the PCRE
-# library. The USE_LIBPCRE flag will likely be changed to mean v2 by
-# default in future releases.
+# The USE_LIBPCRE flag is a synonym for USE_LIBPCRE2, in previous
+# versions it meant the same thing USE_LIBPCRE1 does now. Define
+# USE_LIBPCRE1 instead if you'd like to use the legacy version 1 of
+# the PCRE library.
 #
 # Define LIBPCREDIR=/foo/bar if your PCRE header and library files are in
 # /foo/bar/include and /foo/bar/lib directories.
@@ -1090,18 +1090,17 @@ ifdef NO_LIBGEN_H
 	COMPAT_OBJS += compat/basename.o
 endif
 
-USE_LIBPCRE1 ?= $(USE_LIBPCRE)
-
-ifneq (,$(USE_LIBPCRE1))
-	ifdef USE_LIBPCRE2
-$(error Only set USE_LIBPCRE1 (or its alias USE_LIBPCRE) or USE_LIBPCRE2, not both!)
-	endif
+USE_LIBPCRE2 ?= $(USE_LIBPCRE)
 
+ifdef USE_LIBPCRE1
 	BASIC_CFLAGS += -DUSE_LIBPCRE1
 	EXTLIBS += -lpcre
 endif
 
-ifdef USE_LIBPCRE2
+ifneq (,$(USE_LIBPCRE2))
+	ifdef USE_LIBPCRE1
+$(error Only set USE_LIBPCRE2 (or its alias USE_LIBPCRE) or USE_LIBPCRE1, not both!)
+	endif
 	BASIC_CFLAGS += -DUSE_LIBPCRE2
 	EXTLIBS += -lpcre2-8
 endif
diff --git a/configure.ac b/configure.ac
index 11d083fbe0..f9659daeb7 100644
--- a/configure.ac
+++ b/configure.ac
@@ -255,25 +255,25 @@ GIT_PARSE_WITH([openssl]))
 # Perl-compatible regular expressions instead of standard or extended
 # POSIX regular expressions.
 #
-# Currently USE_LIBPCRE is a synonym for USE_LIBPCRE1, define
-# USE_LIBPCRE2 instead if you'd like to use version 2 of the PCRE
-# library. The USE_LIBPCRE flag will likely be changed to mean v2 by
-# default in future releases.
+# The USE_LIBPCRE flag is a synonym for USE_LIBPCRE2, in previous
+# versions it meant the same thing USE_LIBPCRE1 does now. Define
+# USE_LIBPCRE1 instead if you'd like to use the legacy version 1 of
+# the PCRE library.
 #
 # Define LIBPCREDIR=/foo/bar if your PCRE header and library files are in
 # /foo/bar/include and /foo/bar/lib directories.
 #
 AC_ARG_WITH(libpcre,
-AS_HELP_STRING([--with-libpcre],[synonym for --with-libpcre1]),
+AS_HELP_STRING([--with-libpcre],[synonym for --with-libpcre2]),
     if test "$withval" = "no"; then
-	USE_LIBPCRE1=
+	USE_LIBPCRE2=
     elif test "$withval" = "yes"; then
-	USE_LIBPCRE1=YesPlease
+	USE_LIBPCRE2=YesPlease
     else
-	USE_LIBPCRE1=YesPlease
+	USE_LIBPCRE2=YesPlease
 	LIBPCREDIR=$withval
 	AC_MSG_NOTICE([Setting LIBPCREDIR to $LIBPCREDIR])
-        dnl USE_LIBPCRE1 can still be modified below, so don't substitute
+        dnl USE_LIBPCRE2 can still be modified below, so don't substitute
         dnl it yet.
 	GIT_CONF_SUBST([LIBPCREDIR])
     fi)
-- 
2.11.0