From 526f0abf6de62adc42bca9dbdc63d50e36138dfc Mon Sep 17 00:00:00 2001
From: Manuel Jacob <me@manueljacob.de>
Date: Fri, 1 May 2026 11:38:01 -0600
Subject: [PATCH] [PATCH v2 2/2] build: Set default for CPP_FOR_BUILD
 environment variable in all cases.

A default was set in the `"${build}" != "${host}"` case, but not in the
`"${build}" = "${host}"` case.

For a working build, this change should not make any difference. CPP_FOR_BUILD
is passed to build modules as CPP. If not set, autoconf macro AC_PROG_CC infers
CPP by trying various programs. First, it tries "$CC -E", which CPP will
default to in all cases with this patch.

The following command produces the same build directory with and without the
patch:

./configure --build=x86_64-make_autoconf_enable_cross_compiling-linux-gnu --host=x86_64-linux-gnu

The following command produces a Makefile containing `CPP_FOR_BUILD = ` without
the patch and containing `CPP_FOR_BUILD = $(CC_FOR_BUILD) -E` with the patch:

./configure

ChangeLog:

	* configure.ac: Set default for CPP_FOR_BUILD environment variable in all cases.
	* configure: Regenerate.

Signed-off-by: Manuel Jacob <me@manueljacob.de>
---
 configure    | 2 +-
 configure.ac | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/configure b/configure
index 9a6407d2c6f..e2150f50aac 100755
--- a/configure
+++ b/configure
@@ -4318,7 +4318,6 @@ if test "${build}" != "${host}" ; then
   AR_FOR_BUILD=${AR_FOR_BUILD-ar}
   AS_FOR_BUILD=${AS_FOR_BUILD-as}
   CC_FOR_BUILD=${CC_FOR_BUILD-gcc}
-  CPP_FOR_BUILD="${CPP_FOR_BUILD-\$(CC_FOR_BUILD) -E}"
   CXX_FOR_BUILD=${CXX_FOR_BUILD-g++}
   DLLTOOL_FOR_BUILD=${DLLTOOL_FOR_BUILD-dlltool}
   DSYMUTIL_FOR_BUILD=${DSYMUTIL_FOR_BUILD-dsymutil}
@@ -4350,6 +4349,7 @@ else
   WINDRES_FOR_BUILD="${WINDRES_FOR_BUILD-\$(WINDRES)}"
   WINDMC_FOR_BUILD="${WINDMC_FOR_BUILD-\$(WINDMC)}"
 fi
+CPP_FOR_BUILD="${CPP_FOR_BUILD-\$(CC_FOR_BUILD) -E}"
 
 ac_ext=c
 ac_cpp='$CPP $CPPFLAGS'
diff --git a/configure.ac b/configure.ac
index 0854638e8e8..edd53b2bb42 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1453,7 +1453,6 @@ if test "${build}" != "${host}" ; then
   AR_FOR_BUILD=${AR_FOR_BUILD-ar}
   AS_FOR_BUILD=${AS_FOR_BUILD-as}
   CC_FOR_BUILD=${CC_FOR_BUILD-gcc}
-  CPP_FOR_BUILD="${CPP_FOR_BUILD-\$(CC_FOR_BUILD) -E}"
   CXX_FOR_BUILD=${CXX_FOR_BUILD-g++}
   DLLTOOL_FOR_BUILD=${DLLTOOL_FOR_BUILD-dlltool}
   DSYMUTIL_FOR_BUILD=${DSYMUTIL_FOR_BUILD-dsymutil}
@@ -1485,6 +1484,7 @@ else
   WINDRES_FOR_BUILD="${WINDRES_FOR_BUILD-\$(WINDRES)}"
   WINDMC_FOR_BUILD="${WINDMC_FOR_BUILD-\$(WINDMC)}"
 fi
+CPP_FOR_BUILD="${CPP_FOR_BUILD-\$(CC_FOR_BUILD) -E}"
 
 AC_PROG_CC_C99
 AC_PROG_CXX