[PATCH] D127462: [Clang] Begin implementing Plan 9 C extensions

[Keegan Saunders via Phabricator via cfe-commits]

ksaunders added a comment.

Two questions for Clang developers as I work on my next patches:

1. What is the Clang policy for warnings on extension usages? For example, this diff permits redeclaration of typedefs, which is a Plan 9 and Microsoft C extension. Earlier in the file this extension is enabled for Microsoft C as well, however no warning is emitted. In contrast, in Microsoft C if you use an anonymous embedded record in Clang a warning //is emitted// for extension usage. So it's unclear what should be a warning and what shouldn't be.
2. //MSVC Compatibility// has its own dedicated page on the Clang documentation site. Should I add a page for //Plan 9 Compatibility// which details the status of each feature now (and can be updated in subsequent diffs)?


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