[clang] [clang] Check captured variables for noreturn attribute (PR #155213)
Serge Pavlov via cfe-commits
cfe-commits at lists.llvm.org
Wed Oct 29 11:34:02 PDT 2025
https://github.com/spavloff updated https://github.com/llvm/llvm-project/pull/155213
>From 52499a2a3fde7c66f398e5730f782e0faf6f6e2d Mon Sep 17 00:00:00 2001
From: Serge Pavlov <sepavloff at gmail.com>
Date: Mon, 25 Aug 2025 12:20:21 +0700
Subject: [PATCH 1/3] [clang] Check captured variables for noreturn attribute
Anaysis for noreturn attribute now misses the case when an assignment to
a variable is made inside a lambda function call. This change fixes that
case.
---
clang/lib/Sema/AnalysisBasedWarnings.cpp | 35 ++++++++++++++++++++++++
clang/test/SemaCXX/noreturn-vars.cpp | 13 +++++++++
2 files changed, 48 insertions(+)
diff --git a/clang/lib/Sema/AnalysisBasedWarnings.cpp b/clang/lib/Sema/AnalysisBasedWarnings.cpp
index 0b94b1044f072..fe1498003e7da 100644
--- a/clang/lib/Sema/AnalysisBasedWarnings.cpp
+++ b/clang/lib/Sema/AnalysisBasedWarnings.cpp
@@ -467,6 +467,41 @@ struct TransferFunctions : public StmtVisitor<TransferFunctions> {
AllValuesAreNoReturn = false;
}
}
+
+ void VisitCXXOperatorCallExpr(CXXOperatorCallExpr *CE) {
+ if (CE->getOperator() == OO_Call && CE->getNumArgs() > 0) {
+ Expr *Obj = CE->getArg(0)->IgnoreParenCasts();
+ if (auto *MTE = dyn_cast<MaterializeTemporaryExpr>(Obj))
+ Obj = MTE->getSubExpr();
+ if (auto *DRE = dyn_cast<DeclRefExpr>(Obj)) {
+ auto *D = dyn_cast<VarDecl>(DRE->getDecl());
+ if (D->hasInit())
+ Obj = D->getInit();
+ }
+ Visit(Obj);
+ }
+ }
+
+ void VisitLambdaExpr(LambdaExpr *LE) {
+ for (const LambdaCapture &Capture : LE->captures())
+ if (Capture.capturesVariable())
+ if (const VarDecl *VD = dyn_cast<VarDecl>(Capture.getCapturedVar()))
+ if (VD == Var)
+ if (Capture.getCaptureKind() == LCK_ByRef)
+ AllValuesAreNoReturn = false;
+ }
+
+ void VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr *MTE) {
+ Visit(MTE->getSubExpr());
+ }
+
+ void VisitExprWithCleanups(FullExpr *FE) {
+ Visit(FE->getSubExpr());
+ }
+
+ void VisitCXXConstructExpr(CXXConstructExpr *CE) {
+ Visit(CE->getArg(0));
+ }
};
} // namespace
diff --git a/clang/test/SemaCXX/noreturn-vars.cpp b/clang/test/SemaCXX/noreturn-vars.cpp
index ca65fcf5ca31d..3b2473c1bc670 100644
--- a/clang/test/SemaCXX/noreturn-vars.cpp
+++ b/clang/test/SemaCXX/noreturn-vars.cpp
@@ -225,3 +225,16 @@ extern void abc_02(func_type *);
abc_02(&func_ptr);
func_ptr();
} // expected-warning {{function declared 'noreturn' should not return}}
+
+[[noreturn]] void test_lambda() {
+ func_type func_ptr = noret;
+ [&func_ptr]() { func_ptr = ordinary; } ();
+ func_ptr();
+} // expected-warning {{function declared 'noreturn' should not return}}
+
+[[noreturn]] void test_lambda_var(int x) {
+ func_type func_ptr = noret;
+ auto LF = [&](){func_ptr = ordinary;};
+ LF();
+ func_ptr();
+} // expected-warning {{function declared 'noreturn' should not return}}
>From 8c258f43414876636f9d4029cc6c3c2cbcc7b993 Mon Sep 17 00:00:00 2001
From: Serge Pavlov <sepavloff at gmail.com>
Date: Thu, 18 Sep 2025 00:14:48 +0700
Subject: [PATCH 2/3] Addressreview notes
---
clang/lib/Sema/AnalysisBasedWarnings.cpp | 8 ++---
clang/test/SemaCXX/noreturn-vars.cpp | 40 ++++++++++++++++++++++--
2 files changed, 41 insertions(+), 7 deletions(-)
diff --git a/clang/lib/Sema/AnalysisBasedWarnings.cpp b/clang/lib/Sema/AnalysisBasedWarnings.cpp
index fe1498003e7da..b16c9989fbbb4 100644
--- a/clang/lib/Sema/AnalysisBasedWarnings.cpp
+++ b/clang/lib/Sema/AnalysisBasedWarnings.cpp
@@ -480,6 +480,7 @@ struct TransferFunctions : public StmtVisitor<TransferFunctions> {
}
Visit(Obj);
}
+ VisitCallExpr(CE);
}
void VisitLambdaExpr(LambdaExpr *LE) {
@@ -495,12 +496,11 @@ struct TransferFunctions : public StmtVisitor<TransferFunctions> {
Visit(MTE->getSubExpr());
}
- void VisitExprWithCleanups(FullExpr *FE) {
- Visit(FE->getSubExpr());
- }
+ void VisitExprWithCleanups(FullExpr *FE) { Visit(FE->getSubExpr()); }
void VisitCXXConstructExpr(CXXConstructExpr *CE) {
- Visit(CE->getArg(0));
+ if (CE->getNumArgs() > 0)
+ Visit(CE->getArg(0));
}
};
} // namespace
diff --git a/clang/test/SemaCXX/noreturn-vars.cpp b/clang/test/SemaCXX/noreturn-vars.cpp
index 3b2473c1bc670..9b23dc96d9ae0 100644
--- a/clang/test/SemaCXX/noreturn-vars.cpp
+++ b/clang/test/SemaCXX/noreturn-vars.cpp
@@ -226,15 +226,49 @@ extern void abc_02(func_type *);
func_ptr();
} // expected-warning {{function declared 'noreturn' should not return}}
-[[noreturn]] void test_lambda() {
+[[noreturn]] void test_lambda_capture_ref() {
func_type func_ptr = noret;
[&func_ptr]() { func_ptr = ordinary; } ();
func_ptr();
} // expected-warning {{function declared 'noreturn' should not return}}
-[[noreturn]] void test_lambda_var(int x) {
+[[noreturn]] void test_lambda_var_capture_ref() {
func_type func_ptr = noret;
- auto LF = [&](){func_ptr = ordinary;};
+ auto LF = [&func_ptr](){func_ptr = ordinary; };
LF();
func_ptr();
} // expected-warning {{function declared 'noreturn' should not return}}
+
+[[noreturn]] void test_lambda_capture_ref_all() {
+ func_type func_ptr = noret;
+ [&]() { func_ptr = ordinary; } ();
+ func_ptr();
+} // expected-warning {{function declared 'noreturn' should not return}}
+
+[[noreturn]] void test_lambda_var_capture_ref_all() {
+ func_type func_ptr = noret;
+ auto LF = [&](){func_ptr = ordinary; };
+ LF();
+ func_ptr();
+} // expected-warning {{function declared 'noreturn' should not return}}
+
+[[noreturn]] void lambda_capture_by_value() {
+ func_type func_ptr = noret;
+ auto LF = [func_ptr](){ return func_ptr; };
+ LF();
+ func_ptr();
+}
+
+[[noreturn]] void lambda_pass_by_ref() {
+ func_type func_ptr = noret;
+ auto LF = [](func_type &fptr){ fptr = ordinary; };
+ LF(func_ptr);
+ func_ptr();
+} // expected-warning {{function declared 'noreturn' should not return}}
+
+[[noreturn]] void lambda_pass_by_value() {
+ func_type func_ptr = noret;
+ auto LF = [](func_type fptr){ fptr = ordinary; };
+ LF(func_ptr);
+ func_ptr();
+}
>From 3dc5d78a14e0232d5ccc4e14a9cf707111dabdb7 Mon Sep 17 00:00:00 2001
From: Serge Pavlov <sepavloff at gmail.com>
Date: Thu, 30 Oct 2025 01:33:28 +0700
Subject: [PATCH 3/3] Small enhancements
---
clang/lib/Sema/AnalysisBasedWarnings.cpp | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/clang/lib/Sema/AnalysisBasedWarnings.cpp b/clang/lib/Sema/AnalysisBasedWarnings.cpp
index b16c9989fbbb4..88fd63156d002 100644
--- a/clang/lib/Sema/AnalysisBasedWarnings.cpp
+++ b/clang/lib/Sema/AnalysisBasedWarnings.cpp
@@ -475,7 +475,7 @@ struct TransferFunctions : public StmtVisitor<TransferFunctions> {
Obj = MTE->getSubExpr();
if (auto *DRE = dyn_cast<DeclRefExpr>(Obj)) {
auto *D = dyn_cast<VarDecl>(DRE->getDecl());
- if (D->hasInit())
+ if (D && D->hasInit())
Obj = D->getInit();
}
Visit(Obj);
@@ -487,9 +487,8 @@ struct TransferFunctions : public StmtVisitor<TransferFunctions> {
for (const LambdaCapture &Capture : LE->captures())
if (Capture.capturesVariable())
if (const VarDecl *VD = dyn_cast<VarDecl>(Capture.getCapturedVar()))
- if (VD == Var)
- if (Capture.getCaptureKind() == LCK_ByRef)
- AllValuesAreNoReturn = false;
+ if (VD == Var && Capture.getCaptureKind() == LCK_ByRef)
+ AllValuesAreNoReturn = false;
}
void VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr *MTE) {
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