Adding linker flag `-save-temps` resolves the clang-8 error: "unable to make temporary file"

Clang Frontend Using Clang
1

Hi clang users,
I am using Windows10 + Cygwin + Eclipse + LLVM toolchain to build a C/C++
project.

The files compile fine, but linking with `clang++` fails with multiple
`error: unable to make temporary file: No such file or directory`.

    clang++ -o test "source1.bc" "source2.bc" "source3.bc"
    clang-8: error: unable to make temporary file: No such file or directory
    clang-8: error: unable to make temporary file: No such file or directory
    clang-8: error: unable to make temporary file: No such file or directory

Linker generates one error per each object file.

However, when I add the `-save-temps` option to linker, it works OK.

I am launching Eclipse.exe from within Cygwin. I have tried to set TMP,
TEMP to /temp, /temp/, /cygdrive/c/temp, etc, but nothing worked.

What could be the problem?

Thanks,
Danijel Domazet

2

Looks like it writes the files to the current directory - do you have
permission to access the current directory?

3

Thanks David.
Why do you think this could be about current dir?

Isn’t it about TMP (or TEMP or TMPDIR) environment variables?

Thanks,
Danijel Domazet

4

Thanks David.
Why do you think this could be about current dir?
Isn't it about TMP (or TEMP or TMPDIR) environment variables?

Because I ran it locally, and observed that that's where the files
were written to.

5

>
> Thanks David.
> Why do you think this could be about current dir?
> Isn't it about TMP (or TEMP or TMPDIR) environment variables?

Neither the driver option -save-temps nor the linker option
--save-temps (driver option -Wl,--save-temps) respects
TMP/TEMP/TMPDIR.
The temporary files are saved relative to the current working
directory, which can be changed via -working-directory=

6
  • Confidential -
7

Oh, sorry, I didn't read the question in detail about how -save-temps
was making things work when they otherwise were not.

If you run clang with -### it'll show the command lines it's using,
which should show you where it's trying to write the files so you can
change that/make them writable. I'm not sure which variable is used to
influence clang's temporary directory choice, though.

8

Hi David, Hi Fang-rui,

Just to remind, when I add -save-temps flag, linking works, but without this option it fails with:

clang-8: error: unable to make temporary file: No such file or directory
clang-8: error: unable to make temporary file: No such file or directory
clang-8: error: unable to make temporary file: No such file or directory

Here is the output with flags -save-temps, -###:

“/usr/bin/clang-8” “-cc1” “-triple” “x86_64-unknown-windows-cygnus” “-S” “-save-temps=cwd” “-disable-free” “-disable-llvm-verifier” “-discard-value-names” “-main-file-name” “my_files\my_file1.bc” “-mrelocation-model” “pic” “-pic-level” “2” “-mthread-model” “posix” “-fmath-errno” “-masm-verbose” “-mconstructor-aliases” “-munwind-tables” “-target-cpu” “x86-64” “-dwarf-column-info” “-debugger-tuning=gdb” “-momit-leaf-frame-pointer” “-v” “-resource-dir” “/usr/lib/clang/8.0.1” “-fdebug-compilation-dir” “/cygdrive/c/my_projects/prj1/Debug” “-ferror-limit” “19” “-fmessage-length” “0” “-fobjc-runtime=gcc” “-fseh-exceptions” “-fdiagnostics-show-option” “-o” “my_files\my_file1.s” “-x” “ir” “my_files\my_file1.bc” “-faddrsig”

Here is the output without -save-temps, just -###:

“/usr/bin/clang-8” “-cc1” “-triple” “x86_64-unknown-windows-cygnus” “-emit-obj” “-mrelax-all” “-disable-free” “-disable-llvm-verifier” “-discard-value-names” “-main-file-name” “my_files\my_file1.bc” “-mrelocation-model” “pic” “-pic-level” “2” “-mthread-model” “posix” “-fmath-errno” “-masm-verbose” “-mconstructor-aliases” “-munwind-tables” “-target-cpu” “x86-64” “-dwarf-column-info” “-debugger-tuning=gdb” “-momit-leaf-frame-pointer” “-v” “-resource-dir” “/usr/lib/clang/8.0.1” “-fdebug-compilation-dir” “/cygdrive/c/my_projects/prj1/Debug” “-ferror-limit” “19” “-fmessage-length” “0” “-fobjc-runtime=gcc” “-fseh-exceptions” “-fdiagnostics-show-option” “-o” “” “-x” “ir” “my_files\my_file1.bc” “-faddrsig”

So the “-o” “my_files\my_file1.s” vs “-o” “” seems to be the difference. Is there an explanation?

Also, some more output with the output with flags -save-temps, -###:

“/usr/bin/ld” “-m” “i386pep” “–wrap” “_Znwm” “–wrap” “_Znam” “–wrap” “_ZnwmRKSt9nothrow_t” “–wrap” “_ZnamRKSt9nothrow_t” “–wrap” “_ZdlPv” “–wrap” “_ZdaPv” “–wrap” “_ZdlPvRKSt9nothrow_t” “–wrap” “_ZdaPvKSt9nothrow_t” “-Bdynamic” “–tsaware” “-o” “myexecutable” “/usr/lib/crt0.o” “/usr/lib/gcc/x86_64-pc-cygwin/10/crtbegin.o” “-LC:/mylibraries” “-L/usr/lib/gcc/x86_64-pc-cygwin/10” “-L/usr/x86_64-pc-cygwin/lib” “-L/usr/lib” “-L/usr/lib/w32api” “my_files\my_file1.o” “my_files\my_file2.o” " my_files\my_file3.o" “-lnaturedsp” “-lgcc_s” “-gcc” “-lcygwin” “-ladvapi32” “-lshell32” “-luser32” “-lkernel32” “/usr/lib/default-manifest.o” “/usr/lib/gcc/x86_64-pc-cygwin/10/crtend.o”

and with only -###:

“/usr/bin/ld” “-m” “i386pep” “–wrap” “_Znwm” “–wrap” “_Znam” “–wrap” “_ZnwmRKSt9nothrow_t” “–wrap” “_ZnamRKSt9nothrow_t” “–wrap” “_ZdlPv” “–wrap” “_ZdaPv” “–wrap” “_ZdlPvRKSt9nothrow_t” “–wrap” “_ZdaPvKSt9nothrow_t” “-Bdynamic” “–tsaware” “-o” “myexecutable” “/usr/lib/crt0.o” “/usr/lib/gcc/x86_64-pc-cygwin/10/crtbegin.o” “-LC:/mylibraries” “-L/usr/lib/gcc/x86_64-pc-cygwin/10” “-L/usr/x86_64-pc-cygwin/lib” “-L/usr/lib” “-L/usr/lib/w32api” “” “” “” “-lnaturedsp” “-lgcc_s” “-lgcc” “-lcygwin” “-ladvapi32” “-lshell32” “-luser32” “-lkernel32” “/usr/lib/default-manifest.o” “/usr/lib/gcc/x86_64-pc-cygwin/10/crtend.o”

So, again “my_files\my_file1.o” “my_files\my_file2.o” " my_files\my_file3.o" is lost and substituted with empty strings “” “” “”.

Does this info help resolve my problem?

9

Yep, pretty weird that it tries to write to an empty file name.

What’s the exact raw clang command you used that printed that cc1 command line?