https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102537
Bug ID: 102537 Summary: Objective-C: can't use >= USE_FIXUP_BEFORE paths for non-Darwin Product: gcc Version: 10.3.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: objc Assignee: unassigned at gcc dot gnu.org Reporter: mhjacobson at me dot com Target Milestone: --- I am working on a NeXTv2-ABI-compatible Objective-C runtime for a non-Darwin platform (AVR micros). I'd like my Objective-C code to make use of the most modern ABI features, namely those guarded in the code by `flag_next_runtime >= USE_FIXUP_BEFORE`. However, there appears to be no way to control `flag_next_runtime` (short of modifying the compiler source). I can set it to zero with `-fgnu-runtime` or one with `-fnext-runtime`, but `USE_FIXUP_BEFORE` is an encoded Mac OS X version (namely 100600, referring to Snow Leopard). There is Darwin-specific option parsing code (`darwin_override_options()`) that appears to set `flag_next_runtime` based on `-mmacosx-version-min`, but obviously that doesn't run for non-Darwin targets. I could imagine a few approaches to fixing this: 1. Parse `-mmacosx-version-min` even when the target is not Darwin, whenever we're compiling Objective-C. On non-Darwin, this would be interpreted as requesting Objective-C codegen compatible with the Objective-C ABI of the specified release of Mac OS X. 2. Allow an argument to `-fnext-runtime`, with the meaning approximately the same as in #1. 3. Instead of using `flag_next_runtime` as a version number, switch it back to being zero or one, and use a separate flag (perhaps the existing `-fobjc-abi-version`?) to differentiate ABIs.