Pass -U_GLIBCXX_ASSERTIONS when building mrustc as a workaround (not yet
reported, sorry).
--- a/Makefile
+++ b/Makefile
@@ -47,7 +47,7 @@ CXXFLAGS := -g -Wall
 CXXFLAGS += -std=c++14
 #CXXFLAGS += -Wextra
 CXXFLAGS += -O2
-CXXFLAGS += $(CXXFLAGS_EXTRA)
+CXXFLAGS += $(CXXFLAGS_EXTRA) -U_GLIBCXX_ASSERTIONS
 
 CPPFLAGS := -I src/include/ -I src/
 CPPFLAGS += -I tools/common/
--- a/tools/common/Makefile
+++ b/tools/common/Makefile
@@ -12,7 +12,7 @@ OBJS += jobserver.o
 
 CXXFLAGS := -Wall -std=c++14 -g -O2
 
-CXXFLAGS += $(CXXFLAGS_EXTRA)
+CXXFLAGS += $(CXXFLAGS_EXTRA) -U_GLIBCXX_ASSERTIONS
 
 OBJS := $(OBJS:%=$(OBJDIR)%)
 
--- a/tools/dump_hirfile/Makefile
+++ b/tools/dump_hirfile/Makefile
@@ -16,7 +16,7 @@ OBJS := main.o
 
 LINKFLAGS := -g -lpthread -lz
 CXXFLAGS := -Wall -std=c++14 -g -O2
-CXXFLAGS += -I ../common -I ../../src -I ../../src/include
+CXXFLAGS += -I ../common -I ../../src -I ../../src/include -U_GLIBCXX_ASSERTIONS
 
 CXXFLAGS += $(CXXFLAGS_EXTRA)
 LINKFLAGS += $(LINKFLAGS_EXTRA)
--- a/tools/minicargo/Makefile
+++ b/tools/minicargo/Makefile
@@ -23,7 +23,7 @@ OBJS += file_timestamp.o os.o
 
 LINKFLAGS := -g -lpthread
 CXXFLAGS := -Wall -std=c++14 -g -O2
-CXXFLAGS += -I ../common
+CXXFLAGS += -I ../common -U_GLIBCXX_ASSERTIONS
 
 CXXFLAGS += $(CXXFLAGS_EXTRA)
 LINKFLAGS += $(LINKFLAGS_EXTRA)
--- a/tools/mir_opt_test/Makefile
+++ b/tools/mir_opt_test/Makefile
@@ -16,7 +16,7 @@ LIBS := ../../bin/mrustc.a ../../bin/common_lib.a
 
 LINKFLAGS := -g -lpthread -lz
 CXXFLAGS := -Wall -std=c++14 -g -O2
-CXXFLAGS += -I ../common -I ../../src/include -I ../../src -I .
+CXXFLAGS += -I ../common -I ../../src/include -I ../../src -I . -U_GLIBCXX_ASSERTIONS
 CXXFLAGS += -Wno-misleading-indentation	# Gets REALLY confused by the TU_ARM macro
 
 CXXFLAGS += $(CXXFLAGS_EXTRA)
--- a/tools/standalone_miri/Makefile
+++ b/tools/standalone_miri/Makefile
@@ -16,7 +16,7 @@ OBJS += miri.o miri_extern.o miri_intrinsic.o
 
 LINKFLAGS := -g -lpthread
 CXXFLAGS := -Wall -std=c++14 -g -O2
-CXXFLAGS += -I ../common -I ../../src/include -I .
+CXXFLAGS += -I ../common -I ../../src/include -I . -U_GLIBCXX_ASSERTIONS
 CXXFLAGS += -Wno-misleading-indentation	# Gets REALLY confused by the TU_ARM macro
 
 CXXFLAGS += $(CXXFLAGS_EXTRA)
--- a/tools/testrunner/Makefile
+++ b/tools/testrunner/Makefile
@@ -8,7 +8,7 @@ OBJS := main.o path.o
 LINKFLAGS := -g
 CXXFLAGS := -Wall -std=c++14 -g -O2
 
-CXXFLAGS += $(CXXFLAGS_EXTRA)
+CXXFLAGS += $(CXXFLAGS_EXTRA) -U_GLIBCXX_ASSERTIONS
 LINKFLAGS += $(LINKFLAGS_EXTRA)
 
 OBJS := $(OBJS:%=$(OBJDIR)%)