https://github.com/JOE1994 updated
https://github.com/llvm/llvm-project/pull/90625
>From 0a1598d0e00cbbfd0320ea72491500957ddb6b52 Mon Sep 17 00:00:00 2001
From: Youngsuk Kim <youngsuk....@hpe.com>
Date: Tue, 30 Apr 2024 11:18:15 -0500
Subject: [PATCH 1/2] [clang][Sema] Re-use existing BinaryOperator if possible
First round of Sema checks were run at initial parsing step. Creating a new
BinaryOperator instance (with the re-built LHS or RHS) will trigger another
round of Sema checks, which can lead to duplicate diagnostic warning messages.
All we want here is to replace the LHS or RHS with a NonOdrUse version. Don't
create a new BinaryOperator, but simply replace the LHS or RHS of the given
BinaryOperator.
Fixes #45783
---
clang/lib/Sema/SemaExpr.cpp | 7 +++----
clang/test/CXX/drs/dr7xx.cpp | 2 --
2 files changed, 3 insertions(+), 6 deletions(-)
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 0c37f43f75401b..0cca02c338954a 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -19707,18 +19707,17 @@ static ExprResult
rebuildPotentialResultsAsNonOdrUsed(Sema &S, Expr *E,
ExprResult Sub = Rebuild(LHS);
if (!Sub.isUsable())
return Sub;
- LHS = Sub.get();
+ BO->setLHS(Sub.get());
// -- If e is a comma expression, ...
} else if (BO->getOpcode() == BO_Comma) {
ExprResult Sub = Rebuild(RHS);
if (!Sub.isUsable())
return Sub;
- RHS = Sub.get();
+ BO->setRHS(Sub.get());
} else {
break;
}
- return S.BuildBinOp(nullptr, BO->getOperatorLoc(), BO->getOpcode(),
- LHS, RHS);
+ return ExprResult(BO);
}
// -- If e has the form (e1)...
diff --git a/clang/test/CXX/drs/dr7xx.cpp b/clang/test/CXX/drs/dr7xx.cpp
index 69ee6d6d4e6ae0..0300dae08d6d31 100644
--- a/clang/test/CXX/drs/dr7xx.cpp
+++ b/clang/test/CXX/drs/dr7xx.cpp
@@ -28,10 +28,8 @@ namespace cwg712 { // cwg712: partial
use(a);
use((a));
use(cond ? a : a);
- // FIXME: should only warn once
use((cond, a));
// expected-warning@-1 {{left operand of comma operator has no effect}}
- // expected-warning@-2 {{left operand of comma operator has no effect}}
(void)a;
// expected-error@-1 {{reference to local variable 'a' declared in
enclosing function 'cwg712::f'}} FIXME
>From a7ea985860e0905b1904d58b188a66b94f236fb6 Mon Sep 17 00:00:00 2001
From: Youngsuk Kim <youngsuk....@hpe.com>
Date: Wed, 1 May 2024 14:32:10 -0500
Subject: [PATCH 2/2] Add release-note item
---
clang/docs/ReleaseNotes.rst | 3 +++
1 file changed, 3 insertions(+)
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 2c5308fbcb319a..ee2387245b6495 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -502,6 +502,9 @@ Bug Fixes in This Version
The values of 0 and 1 block any unrolling of the loop. This keeps the same
behavior with GCC.
Fixes (`#88624 <https://github.com/llvm/llvm-project/issues/88624>`_).
+- Clang will no longer emit a duplicate -Wunused-value warning for an
expression
+ `(A, B)` which evaluates to glvalue `B` that can be converted to non
ODR-use. (#GH45783)
+
Bug Fixes to Compiler Builtins
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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