[LLVMbugs] [Bug 8312] New: clang doesn't handle -M/-MF properly

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=8312

           Summary: clang doesn't handle -M/-MF properly
           Product: clang
           Version: unspecified
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: Driver
        AssignedTo: unassignedclangbugs at nondot.org
        ReportedBy: nicholas at mxc.ca
                CC: llvmbugs at cs.uiuc.edu, daniel at zuster.org


There's a couple problems with the handling of the -MF flag. Let's compare with
gcc 4.2:

$ gcc-4.2 hello.c -M -MF hello.d -c -o hello.o
$ file hello.d hello.o
hello.d: ASCII text
hello.o: empty
$ rm hello.d hello.o
$ clang hello.c -M -MF hello.d -c -o hello.o
clang: warning: argument unused during compilation: '-MF hello.d'
clang: warning: argument unused during compilation: '-c'
$ llvm-commit/Debug+Asserts/bin/clang hello.c -MF hello.d -o hello.o
$ file hello.d hello.o
hello.d: ERROR: cannot open `hello.d' (No such file or directory)
hello.o: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), dynamically
linked (uses shared libs), for GNU/Linux 2.6.18, not stripped

I see two problems:
 - GCC requires either -M or -MM whenever -MF is specified. Clang forbids them.
 - Clang doesn't respect both -c and -M at the same time.

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