truncLongCastAssignment and truncLongCastReturn

Message: int result is assigned to long variable. If the variable is long to avoid loss of information, then you have loss of information.

Category: Type Safety

Severity: Style

Language: C/C++

Description

This checker warns when a calculation has type 'int' and it could potentially overflow that and the result is implicitly or explicitly converted to a larger integer type after the loss of information has already occured.

Motivation

The motivation of this checker is to catch bugs. Unintentional loss of information.

How to fix

You can fix these warnings by:

1. Add explicit cast to avoid loss of information
2. Explicitly truncate the result
3. Change type of assigned variable

Before:

void foo(int32_t y) {
    int64_t x = y * y; // <- warning
}

After (explicit cast):

void foo(int32_t y) {
    int64_t x = (int64_t)y * y; // <- 64-bit multiplication
}

After (explicitly truncate the result):

void foo(int32_t y) {
    int64_t x = (int32_t)(y * y); // redundant cast makes it explicit that your intention is to truncate the result to 32-bit
}

After (change type of assigned variable):

void foo(int32_t y) {
    int32_t x = y * y;
}