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Compiler User Guide

Preface Overview of the Compiler Getting Started with the Compiler Compiler command-line syntax Compiler command-line options listed by group Default compiler behavior Order of compiler command-line options Using stdin to input source code to the compiler Directing output to stdout Filename suffixes recognized by the compiler Compiler output files Factors influencing how the compiler searches for Compiler command-line options and search paths Compiler search rules and the current place The ARMCC5INC environment variable Code compatibility between separately compiled and Linker feedback during compilation Unused function code Minimizing code size by eliminating unused functio Compilation build time Compilation build time Minimizing compilation build time Minimizing compilation build time with a single ar Effect of --multifile on compilation build time Minimizing compilation build time with parallel ma Compilation build time on Windows Compiler Features Compiler Coding Practices Compiler Diagnostic Messages Using the Inline and Embedded Assemblers of the AR Compiler Command-line Options Language Extensions Compiler-specific Features C and C++ Implementation Details What is Semihosting? Via File Syntax Summary Table of GNU Language Extensions Standard C Implementation Definition Standard C++ Implementation Definition C and C++ Compiler Implementation Limits

Compiler search rules and the current place

2.11 Compiler search rules and the current place

By default, the compiler uses Berkeley UNIX search rules, so source files and #include header files are searched for relative to the current place. The current place is the directory containing the source or header file currently being processed by the compiler.

When a file is found relative to an element of the search path, the directory containing that file becomes the new current place. When the compiler has finished processing that file, it restores the previous current place. At each instant there is a stack of current places corresponding to the stack of nested #include directives. For example, if the current place is the include directory ...\include, and the compiler is seeking the include file sys\defs.h, it locates ...\include\sys\defs.h if it exists. When the compiler begins to process defs.h, the current place becomes ...\include\sys. Any file included by defs.h that is not specified with an absolute path name, is searched for relative to ...\include\sys.
The original current place ...\include is restored only when the compiler has finished processing defs.h.
You can disable the stacking of current places by using the compiler option --kandr_include. This option makes the compiler use Kernighan and Ritchie search rules whereby each nonrooted user #include is searched for relative to the directory containing the source file that is being compiled.
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