I'm looking for an option to gcc that will make it read a source file from the standard input, mainly so I could do something like this to generate an object file from a tool like flex that generates C code (flex's -t option writes the generated C to the standard output):
flex -t lexer.l | gcc -o lexer.o -magic-option-here
because I don't really care about the generated C file.
Does something like this exist, or do I have to use temporary files?
Yes, but you have to specify the language using the -x option:
# Specify input file as stdin, language as C
flex -t lexer.l | gcc -o lexer.o -xc -
flex -t lexer.l | gcc -x c -c -o lexer.o -
Basically you say that the filename is - Specifying that a filename is - is a somewhat standard convention for saying 'standard input'. You also want the -c flag so you're not doing linking. And when gcc reads from standard input, you have to tell it what language this is with -x . -x c says it's C code.