Extended Description

Found in ClangBuiltLinux/linux#859.

$ bin/clang -xc -c /dev/null -o /tmp/null.o
$ bin/llvm-objdump -j .text -h /tmp/null.o # -j and -h work fine

/tmp/null.o: file format elf64-x86-64

Sections:
Idx Name Size VMA Type
2 .text 00000000 0000000000000000 TEXT
$ bin/llvm-objdump -j .text -t /tmp/null.o # -j and -t don't work fine

/tmp/null.o: file format elf64-x86-64

SYMBOL TABLE:
0000000000000000 l df ABS 0000000000000000 null
bin/llvm-objdump: warning: section '.text' mentioned in a -j/--section option, but not found in any input file

The warning for -j should only fire for options (like -h) that iterate over sections. For -t (printing the symbol table), we shouldn't print the warning, even though we never "saw" the section we're looking for (... because we didn't iterate over any sections).

The error is misleading -- either we should omit it, or we should notify the user more directly that -j is not applicable for flags like -t.

GNU objdump prints the same warning for the repro above, but I think they would consider it a bug too.