[WebAssembly][clang] Implicit conversion from 'unsigned long long' to 'double' changes value

[penguin359]

While attempting to cross-compile a project to the target wasm32-unknown-emscripten, a warning followed by a crash was triggered by the following line of code:

double current_diff = 0xFFFFFFFFFFFFFFFFULL;

I understand that that value is not precisely representable as a double, hence the warning, but I am not sure why it would result in a crash. The full output is here:

  CC       cgminer-cgminer.o
clang-19: warning: -lpthread: 'linker' input unused [-Wunused-command-line-argument]
cgminer.c:582:23: warning: implicit conversion from 'unsigned long long' to 'double' changes value from 18446744073709551615 to 18446744073709551616 [-Wimplicit-const-int-float-conversion]
  582 | double current_diff = 0xFFFFFFFFFFFFFFFFULL;
      |        ~~~~~~~~~~~~   ^~~~~~~~~~~~~~~~~~~~~
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0.      Program arguments: /usr/bin/clang-19 -target wasm32-unknown-emscripten -fignore-exceptions -mllvm -combiner-global-alias-analysis=false -mllvm -enable-emscripten-sjlj -mllvm -disable-lsr --sysroot=/usr/share/emscripten/cache/sysroot -DEMSCRIPTEN -Werror=implicit-function-declaration -Xclang -iwithsysroot/include/fakesdl -Xclang -iwithsysroot/include/compat -DHAVE_CONFIG_H -I. -lpthread -fcommon -fno-strict-aliasing -I./compat/jansson-2.9/src -I./compat/jansson-2.9/src -I./compat/libusb-1.0/libusb -I./lib -I./lib -g3 -O2 -MT cgminer-cgminer.o -MD -MP -MF .deps/cgminer-cgminer.Tpo -c cgminer.c -o cgminer-cgminer.o
1.      <eof> parser at end of file
2.      Code generation
#0 0x00007f37ee0ad40f llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/usr/lib/llvm-19/bin/../lib/libLLVM.so.19.1+0xead40f)
#1 0x00007f37ee0ab119 llvm::sys::RunSignalHandlers() (/usr/lib/llvm-19/bin/../lib/libLLVM.so.19.1+0xeab119)
#2 0x00007f37edff4127 (/usr/lib/llvm-19/bin/../lib/libLLVM.so.19.1+0xdf4127)
#3 0x00007f37eca458d0 (/lib/x86_64-linux-gnu/libc.so.6+0x458d0)
#4 0x00007ffdbc43c220
clang-19: error: clang frontend command failed with exit code 139 (use -v to see invocation)
Ubuntu clang version 19.1.7 (3ubuntu1)
Target: wasm32-unknown-emscripten
Thread model: posix
InstalledDir: /usr/lib/llvm-19/bin
clang-19: note: diagnostic msg:
********************

PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
Preprocessed source(s) and associated run script(s) are located at:
clang-19: note: diagnostic msg: /tmp/cgminer-d3d7e1.c
clang-19: note: diagnostic msg: /tmp/cgminer-d3d7e1.sh
clang-19: note: diagnostic msg:

********************

[penguin359]

cgminer-d3d7e1.c
cgminer-d3d7e1.sh

[penguin359]

After attempting to fix the warning by changing to a representable value, I discovered that the crash is unrelated and still occurs.

[EugeneZelenko]

Could you please try 21 or main branch? Only most recent release is maintained.