g++ has an inaccuracy when following the C++03 standard concerning the equality of types with different linkage. Section 7.5.1 states that: "Two function types with different language linkages are distinct types even if they are otherwise identical.".

Then the following code snippet should not compile:
~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
extern "C" void (*const interruptVectors[])();

typedef void (*ISR_t)(void);

static ISR_t* source_vector_table = const_cast<ISR_t*>(interruptVectors);
~~~~~~~~~~~~~~~~~~~~~~~~
Although interruptVectors is of type const ISR_t* it has C linkage, thus the types should be different and the const_cast should not work.

I have discovered this behavior when compiling a code base with TI's ARM compiler which choked on the aforementioned snippet. A TI employee then referred me to the C++03 standard (https://e2e.ti.com/support/development_tools/compiler/f/343/t/654558), which seems to back the compiler's behavior.