Resolve Issue: coder.inline('never') Does Not Prevent Inlining of Function

Issue

In cases where the coder.inline('never') directive does not prevent inlining of a MATLAB^® function, the code generator removes the function and replaces it with a constant computed return value, even if the function contains coder.inline('never').

For example, consider these functions:

function y = test_inline()
x = local(0);
if(x == 0)
    y = 0;
else 
    y = 1;
end
end

function y = local(x)
coder.inline('never');
y = x;
end

The test_inline function calls local with a constant input value. The generated code for test_inline is:

double test_inline(void)
{
  return 0.0;
}

The code generator inlines local and returns a constant value, even though the MATLAB definition contains the coder.inline('never') directive.

Possible Solutions

To resolve the issue and prevent the code generator from inlining a function, use the coder.ignoreConst function on an input at the function call site in your MATLAB code. This prevents the code generator from returning the function output as a constant value.

Consider this code snippet:

function y = test_inline()
x = local(coder.ignoreConst(0));
if(x == 0)
    y = 0;
else 
    y = 1;
end
end

function y = local(x)
coder.inline('never');
y = x;
end

The generated code for the functions is:

static double local(void)
{
  return 0.0;
}
double test_inline(void)
{
  return !(local() == 0.0);
}