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author | Nicolas Lesser <blitzrakete@gmail.com> | 2019-01-10 19:03:33 +0000 |
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committer | Nicolas Lesser <blitzrakete@gmail.com> | 2019-01-10 19:03:33 +0000 |
commit | 23a55bd3f5c9f0483b82f4ecd489d3c0284d34b9 (patch) | |
tree | 966e978c9f4fe6f886c9f90dea828e9955a67944 /lib/Sema/SemaChecking.cpp | |
parent | 7697c704e135cefdc7f19ba5d6d4749944669be2 (diff) | |
download | clang-23a55bd3f5c9f0483b82f4ecd489d3c0284d34b9.tar.gz |
Fix false positive unsequenced access and modification warning in array subscript expression.
Summary: In the [expr.sub] p1, we can read that for a given E1[E2], E1 is sequenced before E2.
Patch by Mateusz Janek.
Reviewers: rsmith, Rakete1111
Reviewed By: rsmith, Rakete1111
Subscribers: riccibruno, lebedev.ri, Rakete1111, hiraditya, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D50766
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@350874 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Sema/SemaChecking.cpp')
-rw-r--r-- | lib/Sema/SemaChecking.cpp | 44 |
1 files changed, 28 insertions, 16 deletions
diff --git a/lib/Sema/SemaChecking.cpp b/lib/Sema/SemaChecking.cpp index cd96200b81..a47c01daf0 100644 --- a/lib/Sema/SemaChecking.cpp +++ b/lib/Sema/SemaChecking.cpp @@ -11908,30 +11908,42 @@ public: notePostUse(O, E); } - void VisitBinComma(BinaryOperator *BO) { - // C++11 [expr.comma]p1: - // Every value computation and side effect associated with the left - // expression is sequenced before every value computation and side - // effect associated with the right expression. - SequenceTree::Seq LHS = Tree.allocate(Region); - SequenceTree::Seq RHS = Tree.allocate(Region); + void VisitSequencedExpressions(Expr *SequencedBefore, Expr *SequencedAfter) { + SequenceTree::Seq BeforeRegion = Tree.allocate(Region); + SequenceTree::Seq AfterRegion = Tree.allocate(Region); SequenceTree::Seq OldRegion = Region; { - SequencedSubexpression SeqLHS(*this); - Region = LHS; - Visit(BO->getLHS()); + SequencedSubexpression SeqBefore(*this); + Region = BeforeRegion; + Visit(SequencedBefore); } - Region = RHS; - Visit(BO->getRHS()); + Region = AfterRegion; + Visit(SequencedAfter); Region = OldRegion; - // Forget that LHS and RHS are sequenced. They are both unsequenced - // with respect to other stuff. - Tree.merge(LHS); - Tree.merge(RHS); + Tree.merge(BeforeRegion); + Tree.merge(AfterRegion); + } + + void VisitArraySubscriptExpr(ArraySubscriptExpr *ASE) { + // C++17 [expr.sub]p1: + // The expression E1[E2] is identical (by definition) to *((E1)+(E2)). The + // expression E1 is sequenced before the expression E2. + if (SemaRef.getLangOpts().CPlusPlus17) + VisitSequencedExpressions(ASE->getLHS(), ASE->getRHS()); + else + Base::VisitStmt(ASE); + } + + void VisitBinComma(BinaryOperator *BO) { + // C++11 [expr.comma]p1: + // Every value computation and side effect associated with the left + // expression is sequenced before every value computation and side + // effect associated with the right expression. + VisitSequencedExpressions(BO->getLHS(), BO->getRHS()); } void VisitBinAssign(BinaryOperator *BO) { |