Obsolete Precompiled Header (PCH) files
In automatic PCH processing mode the compiler identifies and deletes obsolete PCH files.
Support for Precompiled Header (PCH) files is deprecated from ARM Compiler 5.05 onwards on all platforms. Note that ARM Compiler on Windows 8 never supported PCH files.
The compiler indicates that a PCH file is obsolete, and deletes it, under the following circumstances:
If the PCH file is based on at least one out-of-date header file but is otherwise applicable for the current compilation.
If the PCH file has the same base name as the source file being compiled, for example, xxx.pch and xxx.c, but is not applicable for the current compilation, for example, because you have used different command-line options.
These describe some common cases. You must delete other PCH files as required.