
<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><br class=""><div><blockquote type="cite" class=""><div class="">On Jul 17, 2019, at 2:13 PM, James Y Knight via cfe-dev <<a href="mailto:cfe-dev@lists.llvm.org" class="">cfe-dev@lists.llvm.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" class="">The reason has always been that changing it would undoubtedly break some software which uses features of newer GCCs that aren't implemented in Clang. And there are indeed some of those features, even if they are weird edge cases.</div></div></blockquote><div><br class=""></div><div>What you’re saying leads me to believe that <a href="https://reviews.llvm.org/rL365962" class="">https://reviews.llvm.org/rL365962</a> shouldn’t have been committed. Unless we now decide it’s OK to break code which check GCC quirks?</div><div><br class=""></div><br class=""><blockquote type="cite" class=""><div class=""><div dir="ltr" class=""><div class="">Also, by this point, Clang is a widely-enough used compiler, that I'd expect most maintained software to be attempting to support it explicitly -- best via __has_builtin/__has_feature/__has_attribute/etc tests as applicable, falling back to the GCC version check if those macros don't exist.</div></div><br class=""><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, Jul 17, 2019 at 7:22 AM Simon Atanasyan via cfe-dev <<a href="mailto:cfe-dev@lists.llvm.org" class="">cfe-dev@lists.llvm.org</a>> wrote:<br class=""></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Hi,<br class="">

<br class="">

Recently I get a request to implement in Clang a MIPS-related feature<br class="">

which exists in GCC pre 4.4 and removed in later versions. There is a<br class="">

rationale behind such strange request -- third-party software checks a<br class="">

compiler's compatibility using __GNUC__,__GNUC_MINOR__ macros and<br class="">

selects code dedicated for obsoleted version of GCC.<br class="">

<br class="">

As to me I would use for __GNUC__,__GNUC_MINOR__,__GNUC_PATCHLEVEL__<br class="">

macros defined in the InitializePredefinedMacros function the same<br class="">

values as a minimal GCC version required for building LLVM/Clang [1].<br class="">

Now it's 5.1.0.<br class="">

<br class="">

Is there any rationale to continue declare compatibility with old GCC 4.2.1?<br class="">

<br class="">

[1] <a href="https://llvm.org/docs/GettingStarted.html#software" rel="noreferrer" target="_blank" class="">https://llvm.org/docs/GettingStarted.html#software</a><br class="">

<br class="">

-- <br class="">

Simon Atanasyan<br class="">

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</blockquote></div>

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