What version is your compiler? As of GCC 14 and clang 15 an implicit pointer conversion to int is an error, not merely a warning; and this is without specifying any special conformance or warning modes. I think implicit int conversions have been a constraint violation since at least C99, requiring a diagnostic, though I'm not sure if the switch to an error instead of a warning was prompted by a change in wording in C23 or just a general change in attitude and less concern with failing on pre-existing (but wrong) code.

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ranger_danger 21 hours ago | parent [-]

This was GCC 11. I did try clang 15 and got an error (whereas 14 did not), but my point was that the language spec itself allows this, regardless of any specific compiler, and the original argument (as I understood it) was about the type safety of C and C++ (the language specs) themselves.

	▲	wahern 19 hours ago \| parent [-]
		I'm not very familiar with the C++ standard, but I don't think the C++ standard requires compilation to fail, either. It has similar language to the C standard. Per C++23 4.1.1p2.3, > Otherwise, if a program contains a violation of any diagnosable rule or an occurrence of a construct described in this document as “conditionally-supported” when the implementation does not support that construct, a conforming implementation shall issue at least one diagnostic message. The C++ standard does seem to explicitly require the compiler to reject translation units with a failed static_assert. (The requirements for #error are a little confusing; not sure if a failed #error in a conditional block requires failure.) But I couldn't find a rule that mandates failure for invalid implicit int conversions. Implicit pointer to int conversions are invalid for the same reasons in both C and C++. Basically, AFAICT C++'s type safety in this regard is a matter of historical compiler behavior, and now the major C compilers are adopting that behavior, which they previously had allowed (with a mandatory diagnostic message) for backward compatibility reasons.