CODEWITHSUNDEEP
cconstantsdeclaration
Wasabi
Wasabi

Reputation: 3071

const leading to "formal parameter different from declaration" warning

I have seen multiple questions (this one, for example) on this subject, but none explain the precise behavior I am seeing.

I have two functions, each declared and defined as such:

void PntCreate(Handle *cv);
void PntCreate(Handle * const cv)
{
    //...
}

ErrorCodes wim2Read(const char *fileName, cdCanvas *cv,
                    int onViewport);
ErrorCodes wim2Read(const char * const fileName, cdCanvas * const cv,
                   const int onViewport)
{
    //...
}

The declarations and definitions change only the const qualifiers. From the question linked above, I understand that can lead to warnings since they don't match perfectly. However, what I find curious is that the warning only appear for PntCreate, but not for wim2Read.

What is happening here? I thought it might be because the argument of PntCreate is a struct, but so is the second argument of wim2Read...

Upvotes: 0

Views: 454

Answers (1)

August Karlstrom
August Karlstrom

Reputation: 11377

Your problem is that cv in the definition of wim2Read is a pointer to Canvas instead of a pointer to cdCanvas. The const in both PntCreate and wim2Read has no effect on the contract between the caller and the implementation since parameters are passed by value.

Upvotes: 1

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