https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81878
--- Comment #9 from Richard Biener <rguenth at gcc dot gnu.org> ---
Index: Makefile.in
===================================================================
--- Makefile.in (revision 251140)
+++ Makefile.in (working copy)
@@ -78,7 +78,7 @@ CXX_LFLAGS = \
# Variables for gnattools, native
TOOLS_FLAGS_TO_PASS_NATIVE= \
"CC=../../xgcc -B../../" \
- "CXX=../../xg++ -B../../ $(CXX_LFLAGS)" \
+ "CXX=$(CXX)" \
"CFLAGS=$(CFLAGS) $(WARN_CFLAGS)" \
"LDFLAGS=$(LDFLAGS)" \
"ADAFLAGS=$(ADAFLAGS)" \
@@ -96,7 +96,7 @@ TOOLS_FLAGS_TO_PASS_NATIVE= \
# Variables for regnattools
TOOLS_FLAGS_TO_PASS_RE= \
"CC=../../xgcc -B../../" \
- "CXX=../../xg++ -B../../ $(CXX_LFLAGS)" \
+ "CXX=$(CXX)" \
"CFLAGS=$(CFLAGS)" \
"LDFLAGS=$(LDFLAGS)" \
"ADAFLAGS=$(ADAFLAGS)" \
seems to work for me, both bootstrap and --disable-bootstrap.
