Non-inlined functions

Non-inlined functions

Some functions declared as inline will not be expanded into inline code by the compiler, simply because they are too complicated for the compiler to handle. In this case, the inline specifier is ignored and the function is treated like any other function. The sophistication of the inline code generation depends on the compiler implementor.

Even if a compiler could theoretically inline a function, the compiler is sometimes still forced to generate a “real” function. There are various possible reasons for this:

1. The name of an inline function is used as a pointer-to-function constant.

2. A call to the inline function from within another source file.

3. virtual member functions.

When an inline function is called from a source file, where the function body has not been made available, the compiler generates a real function call (simply because it cannot inline the function). Hence, the real function must exist and be linked like any other function. Fortunately, the placement of inline functions in header files as discussed above will avoid this for any function the compiler decides to inline.