Suppose we have the following command: gcc -IDIR prog1.c -o prog1 Suppose DIR is the system directory as well. So -I is ignored, does it mean?!!: gcc DIR prog1.c -o prog1 or it means?: gcc prog1.c -o prog1 None of them is true I think. Using -I has an effect in the compiling of prog1.c and this effect is not ignored and is considered before prog1.c. When the manual says -I is ignored, it means that, it is like that -I does not exist and has never been used. But in fact the effect of -I has been changed. I think that -I is ignored seems not a good word, it can be replaced with "the effect of -I changes..." Regards On Tue, May 10, 2011 at 10:34 AM, Ian Lance Taylor <iant@xxxxxxxxxx> wrote: > ali hagigat <hagigatali@xxxxxxxxx> writes: > >> My another concern is the explanation of -I option!!: >> "If a standard system include directory, or a directory specified with >> ‘-isystem’, is also specified with ‘-I’, the ‘-I’ option will be >> ignored." >> >> In this case -I option and the directory after that are not ignored!! >> -I is replaced with -isystem. When you have written "ignored", it >> suggests that -I does not be considered. > > I'm not sure I understand the distinction you are drawing. Are you > saying that the compiler behaves as though the -I were replaced with > -isystem? As far as I know, that is not the case. I believe the > compiler really does act as though the -I option were not specified.
