Using /usr/lib/llvm5/bin/llvm-config [version=5.0.2]
g++ -c -Os -fomit-frame-pointer  -o src/llvm/ext/llvm_ext.o src/llvm/ext/llvm_ext.cc -I/usr/lib/llvm5/include -Os -fomit-frame-pointer -fPIC -fvisibility-inlines-hidden -Werror=date-time -std=c++1y -Wall -W -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wno-missing-field-initializers -pedantic -Wno-long-long -Wno-maybe-uninitialized -Wdelete-non-virtual-dtor -Wno-comment -ffunction-sections -fdata-sections -Os -fomit-frame-pointer -Os -DNDEBUG  -fno-exceptions -DLLVM_BUILD_GLOBAL_ISEL -D__STDC_CONSTANT_MACROS
-D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS
gcc -Os -fomit-frame-pointer -fPIC  -Os -fomit-frame-pointer  -c -o src/ext/sigfault.o src/ext/sigfault.c
ar -rcs src/ext/libcrystal.a src/ext/sigfault.o
CRYSTAL_CONFIG_BUILD_COMMIT="645669652f" ./bin/crystal build --verbose --target x86_64-alpine-linux-musl  -D preview_overflow -D compiler_rt --release --progress --threads 4 --link-flags="-Wl,--as-needed"  -o .build/crystal src/compiler/crystal.cr -D without_openssl -D without_zlib
BUG: trying to codegen Int64 &* Int32 (Exception)
Unhandled exception: Error opening file 'crystal' with mode 'r': No such file or directory (Errno)
Failed to raise an exception: END_OF_STACK
[0xd5d706] ???
[0x464e89] ???
[0x465fcc] ???
[0x4766f9] ???
[0x46fb50] ???
[0x46ed4e] ???
[0x46b7e9] ???
[0x49d9b5] ???
[0x46858d] ???
[0x1951d3d] ???
make: *** [Makefile:126: .build/crystal] Error 5
>>> ERROR: crystal: build failed