I often use assignment of longer typed variables to shorter ones, for example int

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Asked: May 19, 20262026-05-19T01:19:29+00:00 2026-05-19T01:19:29+00:00

I often use assignment of longer typed variables to shorter ones, for example int

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I often use assignment of “longer” typed variables to “shorter” ones, for example int to short or uint32_t to uint8_t. One day i decided to find all such cases in my code using gcc, but found to my amazement that gcc didn’t output any warnings!

int long_value;
short short_value;
std::cin >> long_value; // Example input: 32769
short_value = long_value; // MS Visual Studio complains here at warning level 4
std::cout << "Long: " << long_value << '\n'; // My example output: 32769
std::cout << "Short: " << short_value << '\n'; // My example output: -32767

Using gcc -Wall or gcc -Wconversion didn’t help (gcc didn’t output any warning). Actually, it never output any warning for any input and output type (e.g. long and unsigned char).

I have never found an actual bug in gcc so i am almost sure this behavior has a reason.

So why no warning?

Update: i use gcc 4.1.2.