### 4.1 Translation

- How a diagnostic is identified (C90 3.7, C99 and C11 3.10, C90, C99 and C11 5.1.1.3).

  Diagnostics consist of all the output sent to stderr by GCC.

- Whether each nonempty sequence of white-space characters other than new-line is retained or replaced by one space character in translation phase 3 (C90, C99 and C11 5.1.1.2).

  See Implementation-defined behavior in The C Preprocessor.