build: stop overriding user CXXFLAGS

Let users have the final say in regards to CXXFLAGS.

Author: fanquake

build-aux/m4/bitcoin_qt.m4

@@ -117,7 +117,7 @@ AC_DEFUN([BITCOIN_QT_CONFIGURE],[
   TEMP_CPPFLAGS=$CPPFLAGS
   TEMP_CXXFLAGS=$CXXFLAGS
   CPPFLAGS="$QT_INCLUDES $CORE_CPPFLAGS $CPPFLAGS"
-  CXXFLAGS="$PIC_FLAGS $CXXFLAGS"
+  CXXFLAGS="$PIC_FLAGS $CORE_CXXFLAGS $CXXFLAGS"
   _BITCOIN_QT_IS_STATIC
   if test "$bitcoin_cv_static_qt" = "yes"; then
     _BITCOIN_QT_CHECK_STATIC_LIBS
@@ -179,7 +179,7 @@ AC_DEFUN([BITCOIN_QT_CONFIGURE],[
     TEMP_CPPFLAGS=$CPPFLAGS
     TEMP_CXXFLAGS=$CXXFLAGS
     CPPFLAGS="$QT_INCLUDES $CORE_CPPFLAGS $CPPFLAGS"
-    CXXFLAGS="$PIE_FLAGS $CXXFLAGS"
+    CXXFLAGS="$PIE_FLAGS $CORE_CXXFLAGS $CXXFLAGS"
     AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
         #include <QtCore/qconfig.h>
         #ifndef QT_VERSION

configure.ac

@@ -470,7 +470,7 @@ if test "$CXXFLAGS_overridden" = "no"; then
 fi
 
 dnl Don't allow extended (non-ASCII) symbols in identifiers. This is easier for code review.
-AX_CHECK_COMPILE_FLAG([-fno-extended-identifiers], [CXXFLAGS="$CXXFLAGS -fno-extended-identifiers"], [], [$CXXFLAG_WERROR])
+AX_CHECK_COMPILE_FLAG([-fno-extended-identifiers], [CORE_CXXFLAGS="$CORE_CXXFLAGS -fno-extended-identifiers"], [], [$CXXFLAG_WERROR])
 
 enable_sse42=no
 enable_sse41=no
@@ -855,9 +855,15 @@ if test "$use_lcov" = "yes"; then
 
   AX_CHECK_LINK_FLAG([--coverage], [CORE_LDFLAGS="$CORE_LDFLAGS --coverage"],
     [AC_MSG_ERROR([lcov testing requested but --coverage linker flag does not work])])
-  AX_CHECK_COMPILE_FLAG([--coverage],[CXXFLAGS="$CXXFLAGS --coverage"],
+  AX_CHECK_COMPILE_FLAG([--coverage],[CORE_CXXFLAGS="$CORE_CXXFLAGS --coverage"],
     [AC_MSG_ERROR([lcov testing requested but --coverage flag does not work])])
-  CXXFLAGS="$CXXFLAGS -Og"
+  dnl If coverage is enabled, and the user hasn't overriden CXXFLAGS, clear
+  dnl them, to prevent autoconfs "-g -O2" being added. Otherwise we'd end up
+  dnl with "--coverage -Og -O0 -g -O2".
+  if test "$CXXFLAGS_overridden" = "no"; then
+  CXXFLAGS=""
+  fi
+  CORE_CXXFLAGS="$CORE_CXXFLAGS -Og -O0"
 fi
 
 if test "$use_lcov_branch" != "no"; then
@@ -1512,7 +1518,7 @@ AM_CONDITIONAL([ENABLE_SYSCALL_SANDBOX], [test "$use_syscall_sandbox" != "no"])
 
 dnl Check for reduced exports
 if test "$use_reduce_exports" = "yes"; then
-  AX_CHECK_COMPILE_FLAG([-fvisibility=hidden], [CXXFLAGS="$CXXFLAGS -fvisibility=hidden"],
+  AX_CHECK_COMPILE_FLAG([-fvisibility=hidden], [CORE_CXXFLAGS="$CORE_CXXFLAGS -fvisibility=hidden"],
   [AC_MSG_ERROR([Cannot set hidden symbol visibility. Use --disable-reduce-exports.])], [$CXXFLAG_WERROR])
   AX_CHECK_LINK_FLAG([-Wl,--exclude-libs,ALL], [RELDFLAGS="-Wl,--exclude-libs,ALL"], [], [$LDFLAG_WERROR])
 fi
@@ -1875,6 +1881,7 @@ AC_SUBST(BITCOIN_MP_GUI_NAME)
 AC_SUBST(RELDFLAGS)
 AC_SUBST(CORE_LDFLAGS)
 AC_SUBST(CORE_CPPFLAGS)
+AC_SUBST(CORE_CXXFLAGS)
 AC_SUBST(DEBUG_CPPFLAGS)
 AC_SUBST(WARN_CXXFLAGS)
 AC_SUBST(NOWARN_CXXFLAGS)
@@ -2008,7 +2015,7 @@ echo "  CC              = $CC"
 echo "  CFLAGS          = $PTHREAD_CFLAGS $CFLAGS"
 echo "  CPPFLAGS        = $DEBUG_CPPFLAGS $HARDENED_CPPFLAGS $CORE_CPPFLAGS $CPPFLAGS"
 echo "  CXX             = $CXX"
-echo "  CXXFLAGS        = $LTO_CXXFLAGS $DEBUG_CXXFLAGS $HARDENED_CXXFLAGS $WARN_CXXFLAGS $NOWARN_CXXFLAGS $ERROR_CXXFLAGS $GPROF_CXXFLAGS $CXXFLAGS"
+echo "  CXXFLAGS        = $LTO_CXXFLAGS $DEBUG_CXXFLAGS $HARDENED_CXXFLAGS $WARN_CXXFLAGS $NOWARN_CXXFLAGS $ERROR_CXXFLAGS $GPROF_CXXFLAGS $CORE_CXXFLAGS $CXXFLAGS"
 echo "  LDFLAGS         = $LTO_LDFLAGS $PTHREAD_LIBS $HARDENED_LDFLAGS $GPROF_LDFLAGS $CORE_LDFLAGS $LDFLAGS"
 echo "  ARFLAGS         = $ARFLAGS"
 echo

src/Makefile.am

@@ -9,7 +9,7 @@ print-%: FORCE
 DIST_SUBDIRS = secp256k1
 
 AM_LDFLAGS = $(LIBTOOL_LDFLAGS) $(HARDENED_LDFLAGS) $(GPROF_LDFLAGS) $(SANITIZER_LDFLAGS) $(LTO_LDFLAGS) $(CORE_LDFLAGS)
-AM_CXXFLAGS = $(DEBUG_CXXFLAGS) $(HARDENED_CXXFLAGS) $(WARN_CXXFLAGS) $(NOWARN_CXXFLAGS) $(ERROR_CXXFLAGS) $(GPROF_CXXFLAGS) $(SANITIZER_CXXFLAGS) $(LTO_CXXFLAGS)
+AM_CXXFLAGS = $(DEBUG_CXXFLAGS) $(HARDENED_CXXFLAGS) $(WARN_CXXFLAGS) $(NOWARN_CXXFLAGS) $(ERROR_CXXFLAGS) $(GPROF_CXXFLAGS) $(SANITIZER_CXXFLAGS) $(LTO_CXXFLAGS) $(CORE_CXXFLAGS)
 AM_CPPFLAGS = $(DEBUG_CPPFLAGS) $(HARDENED_CPPFLAGS) $(CORE_CPPFLAGS)
 AM_LIBTOOLFLAGS = --preserve-dup-deps
 PTHREAD_FLAGS = $(PTHREAD_CFLAGS) $(PTHREAD_LIBS)