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According to MISRA 2008, concatenation of wide and narrow string literals leads to undefined behavior. This is an implicit undefined behavior according to C99 ISO/IEC 9899:1999.

Noncompliant Code Example

This noncompliant code example concatenates wide and narrow string literals. Although the behavior is undefined in this case, the programmer probably intended to create a wide string literal.

wchar_t *msg = L"This message is very long, so I want to divide it "
                "into two parts.";

Compliant Solution (Wide String Literals)

If the concatenated string needs to be a wide string literal, each element in the concatenation must be a wide string literal, as in this compliant solution.

wchar_t *msg = L"This message is very long, so I want to divide it "
               L"into two parts.";

Compliant Solution (Narrow String Literals)

If wide string literals are unnecessary, it is better to use narrow string literals, as in this compliant solution.

char *msg = "This message is very long, so I want to divide it "
            "into two parts.";

Risk Assessment

The concatenation of wide and narrow string literals leads to undefined behavior.

Related Vulnerabilities

Search for vulnerabilities resulting from the violation of this rule on the CERT website.

Related Guidelines

MISRA Rule 2-13-5

Bibliography

      07. Characters and Strings (STR)