C # error directive and comments

Question

Given:

#error /* */ foo 

Microsoft C ++ displays the /* error message and the GCC foo outputs.

What is right?

Answer 1

GCC is correct.

Comments are replaced (including line breaks) in phase 3 of the translation, preprocessing in phase 4 of the translation (ISO / IEC 9899: 1999, §5.1.1.2).

Therefore, the compiler preprocessing part no longer “sees” line breaks.

And, #error is defined as follows (§6.10.5):

Form preprocessing directive

# error pp-tokens_opt new-line

leads to the fact that the implementation creates a diagnostic message that contains the specified sequence of pre-processing tokens.

So foo should be part of the output.

Answer 2

GCC is correct because it must be replaced with a single space / * ... * / in the standard.