I agree that in theory it would be cool to have C code that uses only defined behavior and works on all platforms for all eternity. However, I think most programs have a fairly clear understanding of what platforms (OS+arch) they are targeting and what compilers they are using to target those platforms.
If the compiler has defined behavior (and you have unit tests for that behavior) on all of these platforms, I don't think it is a huge deal. (Ideally you wouldn't... but sometimes its an accident or unavoidable)
As an example, while struct padding (problem 1) might not technically be in the spec, it is a cornerstone of FFI and every new compiler (that supports C FFI) has a way to compile structs with the same padding.
To my original point, if the article had instead given examples of compilers + architectures that produced different answers, I might feel differently. However, just saying mentioning that these weird edge cases are undefined (in the spec) doesn't mean much to me.
If the compiler has defined behavior (and you have unit tests for that behavior) on all of these platforms, I don't think it is a huge deal. (Ideally you wouldn't... but sometimes its an accident or unavoidable)
As an example, while struct padding (problem 1) might not technically be in the spec, it is a cornerstone of FFI and every new compiler (that supports C FFI) has a way to compile structs with the same padding.
To my original point, if the article had instead given examples of compilers + architectures that produced different answers, I might feel differently. However, just saying mentioning that these weird edge cases are undefined (in the spec) doesn't mean much to me.