5.7.11.4 Iquote Option

The -iquote dir option adds the directory dir to the list of directories to be searched for header files during preprocessing. Directories specified with this option apply only to the quoted form of the directive, for example #include "file", and the directory is searched only after the current working directory has been searched. If this option is used more than once, the directories they specify are searched in a left-to-right order as they appear on the command line.