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Q66310: C4093 Can Be Caused by MASM-Style Comments in _asm Code

Article: Q66310
Product(s): See article
Version(s): 6.00   | 6.00
Operating System(s): MS-DOS | OS/2
Keyword(s): ENDUSER | buglist6.00 | mspl13_c
Last Modified: 24-OCT-1990

The C4093 (Unescaped NewLine in Character Constant in Inactive Code)
warning message will be generated if a section of code is removed with
the preprocessor (#if, #ifdef, etc.) and a constant spans two lines or
is not completed. The following is an example:

void main(void)
{
#ifdef foo
   printf("This is an error\n );
#endif
}

However, the C4093 error can also occur in a MASM-style comment to an
inline assembler instruction. For instance:

void main(void)
{
#ifdef foo
   _asm mov ax, 10  ; "Set return code
#endif
}

In this case, if the code hadn't been inactive, the line would not
have been flagged.

Workarounds
-----------

There following are two workarounds:

1. Do not use MASM-style comments. If C-style comments (// or /* */)
   are used instead, the error is not generated.

2. Add the closing quotation mark to the line.

Microsoft has confirmed this to be a problem in C version 6.00. We are
researching this problem and will post new information here as it
becomes available.

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