I thought I'd seen this reported previously, so this may be a duplicate; however, I cannot now find any specific prior reference.
As noted in follow-up discussion on [#2155], the complex math functions are not being compiled into libmingwex.a, where they were previously to be found in mingwrt-3.x; hence, this is a regression. The cause appears to be a bogus redefinition of complex_SOURCES, which may be corrected by:
diff --git a/Makefile.in b/Makefile.in
--- a/Makefile.in
+++ b/Makefile.in
@@ -302,11 +302,10 @@ complex_SOURCES := \
$(SRCDIR)/ccosh.c \
$(SRCDIR)/cimagl.c \
$(SRCDIR)/cprojl.c \
$(SRCDIR)/csinl.c \
$(SRCDIR)/ctanl.c
-complex_SOURCES := $(wildcard src/libcrt/complex/*.c)
SRCDIR := src/libcrt/ctype
ctype_SOURCES := $(SRCDIR)/isblank.c $(SRCDIR)/iswblank.c
SRCDIR := src/libcrt/fenv
Committed as proposed
No longer an issue, for any
mingwrt-3.xormingwrt-5.xrelease.