CODEWITHSUNDEEP
c++stringstl
user1016736
user1016736

Reputation: 398

How can I tell gcc to warn me of strings being assigned an integer value?

This is my test case (note the WTF comment):

TEST(string_assignment)
{
std::string str;
std::string cheese="Cheese";
str=cheese;
CHECK_EQUAL(cheese, str);

long lval=0;
str=lval; //WTF - why does the compiler allow this ?

str="";
str.append(cheese);
CHECK_EQUAL(cheese, str);
}

I want to catch instances of std::string being assigned something other than another string or a char*. I had assumed that the compiler would reject the incompatible type but it is allowing it.

How can I tell gcc (version 4.4.3) to reject this silliness ? ... or is there some other way to force rejection of these incompatible types being assigned to std::string ?

Upvotes: 2

Views: 239

Answers (3)

Sarfaraz Nawaz
Sarfaraz Nawaz

Reputation: 361772

It compiles because of the following overload:

string& operator=(char)

Use g++ -Wconversion in order to print warning messages.

And g++ -Wconversion -Werror to treat warning as error.

Upvotes: 3

Oliver Charlesworth
Oliver Charlesworth

Reputation: 272772

The reason is that the following overload exists:

string &operator=(char)

The compiler can satisfy your assignment with a single implicit conversion, so it compiles.

I think the -Wconversion GCC flag is supposed to deal with this, but it doesn't seem to work, at least in GCC 4.1.2.

Upvotes: 5

James Kanze
James Kanze

Reputation: 154047

Because it can't. Ultimately, because of C compatibility: a long, like all other built-in numeric types, converts implicitly to a char. So in order to ban this, you'd also have to forbid someString = someChar. Which wouldn't bother me too much, but for whatever reasons, the committee felt was necessary.

Upvotes: 3

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