Implementation of string literal concatenation in C and C++

Question

AFAIK, this question applies equally to C and C++

Step 6 of the \"translation phases\" specified in the C standard (5.1.1.

Answer 1

In the ANSI C standard, this detail is covered in section 5.1.1.2, item (6):

5.1.1.2 Translation phases
...

4. Preprocessing directives are executed and macro invocations are expanded. ...

5. Each source character set member and escape sequence in character constants and string literals is converted to a member of the execution character set.

6. Adjacent character string literal tokens are concatenated and adjacent wide string literal tokens are concatenated.

The standard does not define that the implementation must use a pre-processor and compiler, per se.

Step 4 is clearly a preprocessor responsibility.

Step 5 requires that the "execution character set" be known. This information is also required by the compiler. It is easier to port the compiler to a new platform if the preprocessor does not contain platform dependendencies, so the tendency is to implement step 5, and thus step 6, in the compiler.