[clang] [Clang] skip warnings for constructors marked with the [[noreturn]] attribute (PR #115558)
Oleksandr T. via cfe-commits
cfe-commits at lists.llvm.org
Wed Nov 20 15:34:07 PST 2024
https://github.com/a-tarasyuk updated https://github.com/llvm/llvm-project/pull/115558
>From f63263a1aa4873a63918649ea92352eb5cfe66eb Mon Sep 17 00:00:00 2001
From: Oleksandr T <oleksandr.tarasiuk at outlook.com>
Date: Sat, 9 Nov 2024 00:41:13 +0200
Subject: [PATCH 1/3] [Clang] skip warnings for constructors marked with the
[[noreturn]] attribute
---
clang/docs/ReleaseNotes.rst | 2 ++
clang/lib/Analysis/CFG.cpp | 15 ++++++++++-----
.../CXX/dcl.dcl/dcl.attr/dcl.attr.noreturn/p1.cpp | 12 ++++++++++++
3 files changed, 24 insertions(+), 5 deletions(-)
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index c3424e0e6f34c9..11d0e35d12a786 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -527,6 +527,8 @@ Improvements to Clang's diagnostics
- Clang now diagnoses ``[[deprecated]]`` attribute usage on local variables (#GH90073).
+- Clang now omits warnings for constructors marked with the ``[[noreturn]]`` attribute (#GH63009).
+
Improvements to Clang's time-trace
----------------------------------
diff --git a/clang/lib/Analysis/CFG.cpp b/clang/lib/Analysis/CFG.cpp
index f678ac6f2ff36a..4d83f04c23060a 100644
--- a/clang/lib/Analysis/CFG.cpp
+++ b/clang/lib/Analysis/CFG.cpp
@@ -4889,16 +4889,21 @@ CFGBlock *CFGBuilder::VisitCXXFunctionalCastExpr(CXXFunctionalCastExpr *E,
return Visit(E->getSubExpr(), asc);
}
-CFGBlock *CFGBuilder::VisitCXXTemporaryObjectExpr(CXXTemporaryObjectExpr *C,
+CFGBlock *CFGBuilder::VisitCXXTemporaryObjectExpr(CXXTemporaryObjectExpr *E,
AddStmtChoice asc) {
// If the constructor takes objects as arguments by value, we need to properly
// construct these objects. Construction contexts we find here aren't for the
// constructor C, they're for its arguments only.
- findConstructionContextsForArguments(C);
+ findConstructionContextsForArguments(E);
- autoCreateBlock();
- appendConstructor(Block, C);
- return VisitChildren(C);
+ CXXConstructorDecl *C = E->getConstructor();
+ if (C && C->isNoReturn())
+ Block = createNoReturnBlock();
+ else
+ autoCreateBlock();
+
+ appendConstructor(Block, E);
+ return VisitChildren(E);
}
CFGBlock *CFGBuilder::VisitImplicitCastExpr(ImplicitCastExpr *E,
diff --git a/clang/test/CXX/dcl.dcl/dcl.attr/dcl.attr.noreturn/p1.cpp b/clang/test/CXX/dcl.dcl/dcl.attr/dcl.attr.noreturn/p1.cpp
index 56920ea8e8cf20..a96224dd03e360 100644
--- a/clang/test/CXX/dcl.dcl/dcl.attr/dcl.attr.noreturn/p1.cpp
+++ b/clang/test/CXX/dcl.dcl/dcl.attr/dcl.attr.noreturn/p1.cpp
@@ -49,3 +49,15 @@ void check() {
test_type(g);
test_type(h); // expected-note {{instantiation}}
}
+
+namespace GH63009 {
+struct S {
+ [[noreturn]] S() { throw int {}; }
+};
+
+int test_no_return_constructor() { S(); } // ok
+
+int main() {
+ test_no_return_constructor();
+}
+}
>From 99582e7e30048b07dba57d0c284acf209f53b83e Mon Sep 17 00:00:00 2001
From: Oleksandr T <oleksandr.tarasiuk at outlook.com>
Date: Thu, 21 Nov 2024 01:25:43 +0200
Subject: [PATCH 2/3] suppress warnings for constructor expressions with the
[[noreturn]] attribute
---
clang/lib/Analysis/CFG.cpp | 16 ++++++++------
.../dcl.dcl/dcl.attr/dcl.attr.noreturn/p1.cpp | 11 +++++++---
clang/test/SemaCXX/warn-missing-noreturn.cpp | 22 +++++++++++++++++++
3 files changed, 39 insertions(+), 10 deletions(-)
diff --git a/clang/lib/Analysis/CFG.cpp b/clang/lib/Analysis/CFG.cpp
index 4d83f04c23060a..35cf8c49bd27eb 100644
--- a/clang/lib/Analysis/CFG.cpp
+++ b/clang/lib/Analysis/CFG.cpp
@@ -760,6 +760,12 @@ class CFGBuilder {
void cleanupConstructionContext(Expr *E);
void autoCreateBlock() { if (!Block) Block = createBlock(); }
+ void createConstructorBlock(CXXConstructorDecl *C) {
+ if (C && C->isNoReturn())
+ Block = createNoReturnBlock();
+ else
+ autoCreateBlock();
+ };
CFGBlock *createBlock(bool add_successor = true);
CFGBlock *createNoReturnBlock();
@@ -4830,7 +4836,7 @@ CFGBlock *CFGBuilder::VisitCXXConstructExpr(CXXConstructExpr *C,
// constructor C, they're for its arguments only.
findConstructionContextsForArguments(C);
- autoCreateBlock();
+ createConstructorBlock(C->getConstructor());
appendConstructor(Block, C);
return VisitChildren(C);
@@ -4896,13 +4902,9 @@ CFGBlock *CFGBuilder::VisitCXXTemporaryObjectExpr(CXXTemporaryObjectExpr *E,
// constructor C, they're for its arguments only.
findConstructionContextsForArguments(E);
- CXXConstructorDecl *C = E->getConstructor();
- if (C && C->isNoReturn())
- Block = createNoReturnBlock();
- else
- autoCreateBlock();
-
+ createConstructorBlock(E->getConstructor());
appendConstructor(Block, E);
+
return VisitChildren(E);
}
diff --git a/clang/test/CXX/dcl.dcl/dcl.attr/dcl.attr.noreturn/p1.cpp b/clang/test/CXX/dcl.dcl/dcl.attr/dcl.attr.noreturn/p1.cpp
index a96224dd03e360..afcb133e48a1a8 100644
--- a/clang/test/CXX/dcl.dcl/dcl.attr/dcl.attr.noreturn/p1.cpp
+++ b/clang/test/CXX/dcl.dcl/dcl.attr/dcl.attr.noreturn/p1.cpp
@@ -51,13 +51,18 @@ void check() {
}
namespace GH63009 {
-struct S {
- [[noreturn]] S() { throw int {}; }
+struct S1 {
+ [[noreturn]] S1() { throw int {}; }
+};
+struct S2 {
+ [[noreturn]] ~S2() { throw int {}; }
};
-int test_no_return_constructor() { S(); } // ok
+int test_no_return_constructor() { S1(); } // ok
+int test_no_return_destructor() { S2(); } // ok
int main() {
test_no_return_constructor();
+ test_no_return_destructor();
}
}
diff --git a/clang/test/SemaCXX/warn-missing-noreturn.cpp b/clang/test/SemaCXX/warn-missing-noreturn.cpp
index 400b471600e027..32b49e0a325f26 100644
--- a/clang/test/SemaCXX/warn-missing-noreturn.cpp
+++ b/clang/test/SemaCXX/warn-missing-noreturn.cpp
@@ -122,3 +122,25 @@ namespace PR10801 {
thingy(b);
}
}
+
+namespace GH63009 {
+struct S1 {
+ [[noreturn]] S1();
+};
+
+struct S2 {
+ [[noreturn]] ~S2();
+};
+
+int foo();
+
+int test_1() {
+ S1 s1;
+ foo();
+}
+
+int test_2() {
+ S2 s2;
+ foo();
+}
+}
>From f7e9401c3607d3c4892660464f605e9504d68829 Mon Sep 17 00:00:00 2001
From: Oleksandr T <oleksandr.tarasiuk at outlook.com>
Date: Thu, 21 Nov 2024 01:29:17 +0200
Subject: [PATCH 3/3] update release notes
---
clang/docs/ReleaseNotes.rst | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 8834a8236cce1c..4887594af9ead7 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -555,7 +555,8 @@ Improvements to Clang's diagnostics
getS(); // Now diagnoses "Reason 2", previously diagnoses "Reason 1"
}
-- Clang now omits warnings for constructors marked with the ``[[noreturn]]`` attribute (#GH63009).
+- Clang now correctly recognises code after a call to a ``[[noreturn]]`` constructor
+ as unreachable (#GH63009).
Improvements to Clang's time-trace
----------------------------------
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