[PATCH] D126864: [clang] Introduce -fstrict-flex-arrays=<n> for stricter handling of flexible arrays

[serge via Phabricator via cfe-commits]

serge-sans-paille added a comment.

@kees are you ok with current state?



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Comment at: clang/lib/CodeGen/CGExpr.cpp:906
       // member, only a T[0] or T[] member gets that treatment.
+      // Under StrictFlexArraysLevel, obey c99+ that disallows FAM in union, see
+      // C11 6.7.2.1 §18
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jyknight wrote:
> I believe this bit is incorrect -- it should just go back to 'return true;'. The StrictFlexArraysLevel check above already eliminates the cases we want to eliminate (size==1 in strictness-level 2.)
Well, if we are in strictness-level 2, with an undefined size or size = 0, we can still reach that path, and don't want to return 'true' because FAM in union are in invalid per the standard.


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Comment at: clang/lib/StaticAnalyzer/Core/MemRegion.cpp:792
 
+      if (getContext().getLangOpts().StrictFlexArrays >= 2)
+        return false;
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jyknight wrote:
> Yuk, another place that is weird and doesn't handle StrictFlexArrays as expected...
I've been able to slightly move that check below, without impacting test suite. Also added a FIXME because `Opts.ShouldConsiderSingleElementArraysAsFlexibleArrayMembers` looks redundant with `-fstrict-flex-arrays`


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  https://reviews.llvm.org/D126864/new/

https://reviews.llvm.org/D126864