[PATCH] D58154: Add support for -fpermissive.

[Aaron Ballman via Phabricator via cfe-commits]

aaron.ballman added a comment.

In D58154#1420344 <https://reviews.llvm.org/D58154#1420344>, @rsmith wrote:

> I don't have particularly strong feelings one way or the other about accepting `-fpermissive` at all. For GCC compatibility, it seems like a moderately useful thing to support, but I don't think we have any interest in accepting everything that GCC accepts under `-fpermissive`.


Agreed that we shouldn't accept everything GCC accepts under `-fpermissive`.

> Perhaps the better choice is to not provide the flag at all, rather than to provide something that has the same interface but doesn't accept the same code. If not that, making `-fpermissive` an alias for `-Wno-error=everything` is probably a better approach than that of this patch.

Past experience has shown that when we add a flag for compatibility purposes, users expect compatibility and when I saw the title "Add support for -fpermissive", I got very scared that we meant *all* of `-fpermissive` (especially when the rationale was for GCC compatibility). I think we should avoid spelling this `-fpermissive`.

If we go with a different name for the flag, then the user has to update their build scripts to get code to compile with Clang, which means it shouldn't be too onerous for them to spell out the specific diagnostics they need disabled (and it sort of forces them into somewhat better code hygiene by not disabling all diagnostics). I'm kind of leaning towards not providing a flag at all.


Repository:
  rC Clang

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https://reviews.llvm.org/D58154