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The Strict Aliasing Situation Is Pretty Bad (2016)
’ll start with a quick review of the strict aliasing rules in C and C++ and then present some less well-known material. Strict Aliasing Compiler optimizations are often shot down by the potential for pointers to be aliases.
An exception to the strict aliasing rules is made for pointers to character types, so it is always OK to inspect an object’s representation via an array of chars. Many aliasing rule violations can be found in this book about object oriented C. Some build systems, such as Linux’s, invoke GCC with its -fno-strict-aliasing flag to avoid problems. Update based on some comments from Josh Haberman and Sam Tobin-Hochstadt: It looks like the specific case where the struct representing the derived type includes its parent as its first member should not trigger UB.
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