Sadly -fsanitize=undefined does not work in MSYS2/mingw-w64. Cannot find -lubsan at link time.

ubsan_shell_session.txt

$ cat test.c
int main() { return 0; }
$ gcc -v -fsanitize=undefined test.c
Using built-in specs.
COLLECT_GCC=D:\msys64\mingw64\bin\gcc.exe
COLLECT_LTO_WRAPPER=D:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.2.0/lto-wrapper.exe
Target: x86_64-w64-mingw32
Configured with: ../gcc-5.2.0/configure --prefix=/mingw64 --with-local-prefix=/mingw64/local --build=x86_64-w64-mingw32 --host=x86_64-w64-mingw32 --target=x86_64-w64-mingw32 --with-native-system-header-dir=/mingw64/x86_64-w64-mingw32/include --libexecdir=/mingw64/lib --with-gxx-include-dir=/mingw64/include/c++/5.2.0 --enable-bootstrap --with-arch=x86-64 --with-tune=generic --enable-languages=c,lto,c++,objc,obj-c++,fortran,ada --enable-shared --enable-static --enable-libatomic --enable-threads=posix --enable-graphite --enable-fully-dynamic-string --enable-libstdcxx-time=yes --disable-libstdcxx-pch --disable-libstdcxx-debug --enable-version-specific-runtime-libs --disable-isl-version-check --enable-lto --enable-libgomp --disable-multilib --enable-checking=release --disable-rpath --disable-win32-registry --disable-nls --disable-werror --disable-symvers --with-libiconv --with-system-zlib --with-gmp=/mingw64 --with-mpfr=/mingw64 --with-mpc=/mingw64 --with-isl=/mingw64 --with-pkgversion='Rev3, Built by MSYS2 project' --with-bugurl=http://sourceforge.net/projects/msys2 --with-gnu-as --with-gnu-ld
Thread model: posix
gcc version 5.2.0 (Rev3, Built by MSYS2 project)
COLLECT_GCC_OPTIONS='-v' '-fsanitize=undefined' '-mtune=generic' '-march=x86-64'
 D:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.2.0/cc1.exe -quiet -v -iprefix D:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.2.0/ -D_REENTRANT test.c -quiet -dumpbase test.c -mtune=generic -march=x86-64 -auxbase test -version -fsanitize=undefined -o D:\msys64\tmp\ccDzMBie.s
GNU C11 (Rev3, Built by MSYS2 project) version 5.2.0 (x86_64-w64-mingw32)
        compiled by GNU C version 5.2.0, GMP version 6.0.0, MPFR version 3.1.3, MPC version 1.0.3
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
ignoring duplicate directory "D:/msys64/mingw64/lib/gcc/../../lib/gcc/x86_64-w64-mingw32/5.2.0/include"
ignoring nonexistent directory "D:/develop/msys64/mingw64/include"
ignoring nonexistent directory "/mingw64/include"
ignoring duplicate directory "D:/msys64/mingw64/lib/gcc/../../lib/gcc/x86_64-w64-mingw32/5.2.0/include-fixed"
ignoring duplicate directory "D:/msys64/mingw64/lib/gcc/../../lib/gcc/x86_64-w64-mingw32/5.2.0/../../../../x86_64-w64-mingw32/include"
ignoring nonexistent directory "D:/develop/msys64/mingw64/x86_64-w64-mingw32/include"
#include "..." search starts here:
#include <...> search starts here:
 D:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.2.0/include
 D:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.2.0/../../../../include
 D:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.2.0/include-fixed
 D:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.2.0/../../../../x86_64-w64-mingw32/include
End of search list.
GNU C11 (Rev3, Built by MSYS2 project) version 5.2.0 (x86_64-w64-mingw32)
        compiled by GNU C version 5.2.0, GMP version 6.0.0, MPFR version 3.1.3, MPC version 1.0.3
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 990db83b15eadedbea09211fa6feb12a
COLLECT_GCC_OPTIONS='-v' '-fsanitize=undefined' '-mtune=generic' '-march=x86-64'
 D:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.2.0/../../../../x86_64-w64-mingw32/bin/as.exe -v -o D:\msys64\tmp\ccmnRJTo.o D:\msys64\tmp\ccDzMBie.s
GNU assembler version 2.25.1 (x86_64-w64-mingw32) using BFD version (GNU Binutils) 2.25.1
COMPILER_PATH=D:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.2.0/;D:/msys64/mingw64/bin/../lib/gcc/;D:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.2.0/../../../../x86_64-w64-mingw32/bin/
LIBRARY_PATH=D:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.2.0/;D:/msys64/mingw64/bin/../lib/gcc/;D:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.2.0/../../../../x86_64-w64-mingw32/lib/../lib/;D:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.2.0/../../../../lib/;D:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.2.0/../../../../x86_64-w64-mingw32/lib/;D:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.2.0/../../../
COLLECT_GCC_OPTIONS='-v' '-fsanitize=undefined' '-mtune=generic' '-march=x86-64'
 D:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.2.0/collect2.exe -plugin D:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.2.0/liblto_plugin-0.dll -plugin-opt=D:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.2.0/lto-wrapper.exe -plugin-opt=-fresolution=D:\msys64\tmp\cc6ek00q.res -plugin-opt=-pass-through=-lmingw32 -plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lgcc_eh -plugin-opt=-pass-through=-lmoldname -plugin-opt=-pass-through=-lmingwex -plugin-opt=-pass-through=-lmsvcrt -plugin-opt=-pass-through=-lpthread -plugin-opt=-pass-through=-ladvapi32 -plugin-opt=-pass-through=-lshell32 -plugin-opt=-pass-through=-luser32 -plugin-opt=-pass-through=-lkernel32 -plugin-opt=-pass-through=-lmingw32 -plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lgcc_eh -plugin-opt=-pass-through=-lmoldname -plugin-opt=-pass-through=-lmingwex -plugin-opt=-pass-through=-lmsvcrt -m i386pep -Bdynamic D:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.2.0/../../../../x86_64-w64-mingw32/lib/../lib/crt2.o D:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.2.0/crtbegin.o -LD:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.2.0 -LD:/msys64/mingw64/bin/../lib/gcc -LD:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.2.0/../../../../x86_64-w64-mingw32/lib/../lib -LD:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.2.0/../../../../lib -LD:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.2.0/../../../../x86_64-w64-mingw32/lib -LD:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.2.0/../../.. D:\msys64\tmp\ccmnRJTo.o -lubsan -lmingw32 -lgcc -lgcc_eh -lmoldname -lmingwex -lmsvcrt -lpthread -ladvapi32 -lshell32 -luser32 -lkernel32 -lmingw32 -lgcc -lgcc_eh -lmoldname -lmingwex -lmsvcrt D:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.2.0/../../../../x86_64-w64-mingw32/lib/../lib/default-manifest.o D:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.2.0/crtend.o
D:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lubsan
collect2.exe: error: ld returned 1 exit status