[clang] 47abe86 - [clang][CFG] Sequence RHS before LHS for overloaded assignment operators in CFG to match C++17 rules (#181113)
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Sun Feb 15 06:04:51 PST 2026
Author: Alex Wang
Date: 2026-02-15T15:04:47+01:00
New Revision: 47abe868314d2b2d71d188723bda41ea3d4641f7
URL: https://github.com/llvm/llvm-project/commit/47abe868314d2b2d71d188723bda41ea3d4641f7
DIFF: https://github.com/llvm/llvm-project/commit/47abe868314d2b2d71d188723bda41ea3d4641f7.diff
LOG: [clang][CFG] Sequence RHS before LHS for overloaded assignment operators in CFG to match C++17 rules (#181113)
Fixes #180521
Added:
clang/test/Analysis/cfg-assignment-eval-order.cpp
Modified:
clang/lib/Analysis/CFG.cpp
clang/test/Analysis/missing-bind-temporary.cpp
clang/test/Analysis/scopes-cfg-output.cpp
Removed:
################################################################################
diff --git a/clang/lib/Analysis/CFG.cpp b/clang/lib/Analysis/CFG.cpp
index 1b6cfc716cf93..10a7c5b2c8344 100644
--- a/clang/lib/Analysis/CFG.cpp
+++ b/clang/lib/Analysis/CFG.cpp
@@ -656,6 +656,7 @@ class CFGBuilder {
bool ExternallyDestructed = false);
CFGBlock *VisitStmt(Stmt *S, AddStmtChoice asc);
CFGBlock *VisitChildren(Stmt *S);
+ CFGBlock *VisitCallExprChildren(CallExpr *C);
CFGBlock *VisitNoRecurse(Expr *E, AddStmtChoice asc);
CFGBlock *VisitOMPExecutableDirective(OMPExecutableDirective *D,
AddStmtChoice asc);
@@ -731,6 +732,8 @@ class CFGBuilder {
CFGBlock *VisitBinaryOperatorForTemporaryDtors(BinaryOperator *E,
bool ExternallyDestructed,
TempDtorContext &Context);
+ CFGBlock *VisitCXXOperatorCallExprForTemporaryDtors(CXXOperatorCallExpr *E,
+ TempDtorContext &Context);
CFGBlock *VisitCXXBindTemporaryExprForTemporaryDtors(
CXXBindTemporaryExpr *E, bool ExternallyDestructed, TempDtorContext &Context);
CFGBlock *VisitConditionalOperatorForTemporaryDtors(
@@ -2542,6 +2545,19 @@ CFGBlock *CFGBuilder::VisitChildren(Stmt *S) {
return B;
}
+CFGBlock *CFGBuilder::VisitCallExprChildren(CallExpr *C) {
+ // For overloaded assignment operators, visit arguments in reverse order (LHS
+ // then RHS) so that RHS is sequenced before LHS in the CFG, matching C++17
+ // sequencing rules.
+ if (auto *OCE = dyn_cast<CXXOperatorCallExpr>(C);
+ OCE && OCE->isAssignmentOp()) {
+ Visit(OCE->getArg(0));
+ Visit(OCE->getArg(1));
+ return Visit(OCE->getCallee());
+ }
+ return VisitChildren(C);
+}
+
CFGBlock *CFGBuilder::VisitInitListExpr(InitListExpr *ILE, AddStmtChoice asc) {
if (asc.alwaysAdd(*this, ILE)) {
autoCreateBlock();
@@ -2879,7 +2895,7 @@ CFGBlock *CFGBuilder::VisitCallExpr(CallExpr *C, AddStmtChoice asc) {
autoCreateBlock();
appendCall(Block, C);
- return VisitChildren(C);
+ return VisitCallExprChildren(C);
}
if (Block) {
@@ -2903,7 +2919,7 @@ CFGBlock *CFGBuilder::VisitCallExpr(CallExpr *C, AddStmtChoice asc) {
addSuccessor(Block, &cfg->getExit());
}
- return VisitChildren(C);
+ return VisitCallExprChildren(C);
}
CFGBlock *CFGBuilder::VisitChooseExpr(ChooseExpr *C,
@@ -5103,6 +5119,10 @@ CFGBlock *CFGBuilder::VisitForTemporaryDtors(Stmt *E, bool ExternallyDestructed,
ExternallyDestructed,
Context);
+ case Stmt::CXXOperatorCallExprClass:
+ return VisitCXXOperatorCallExprForTemporaryDtors(
+ cast<CXXOperatorCallExpr>(E), Context);
+
case Stmt::CXXBindTemporaryExprClass:
return VisitCXXBindTemporaryExprForTemporaryDtors(
cast<CXXBindTemporaryExpr>(E), ExternallyDestructed, Context);
@@ -5243,6 +5263,18 @@ CFGBlock *CFGBuilder::VisitBinaryOperatorForTemporaryDtors(
return VisitChildrenForTemporaryDtors(E, ExternallyDestructed, Context);
}
+CFGBlock *CFGBuilder::VisitCXXOperatorCallExprForTemporaryDtors(
+ CXXOperatorCallExpr *E, TempDtorContext &Context) {
+ if (E->isAssignmentOp()) {
+ // For assignment operators, the RHS expression is evaluated before the LHS
+ // expression, so prepend temporary destructors for the RHS first.
+ CFGBlock *RHSBlock = VisitForTemporaryDtors(E->getArg(1), false, Context);
+ CFGBlock *LHSBlock = VisitForTemporaryDtors(E->getArg(0), false, Context);
+ return LHSBlock ? LHSBlock : RHSBlock;
+ }
+ return VisitChildrenForTemporaryDtors(E, false, Context);
+}
+
CFGBlock *CFGBuilder::VisitCXXBindTemporaryExprForTemporaryDtors(
CXXBindTemporaryExpr *E, bool ExternallyDestructed, TempDtorContext &Context) {
// First add destructors for temporaries in subexpression.
diff --git a/clang/test/Analysis/cfg-assignment-eval-order.cpp b/clang/test/Analysis/cfg-assignment-eval-order.cpp
new file mode 100644
index 0000000000000..8acf2684aa682
--- /dev/null
+++ b/clang/test/Analysis/cfg-assignment-eval-order.cpp
@@ -0,0 +1,55 @@
+// RUN: %clang_analyze_cc1 -analyzer-checker=debug.DumpCFG -std=c++17 %s > %t 2>&1
+// RUN: FileCheck --input-file=%t %s
+
+// CHECK-LABEL: void test_eval_order(Map &m, int a, int b)
+// CHECK: 1: operator=
+// CHECK-NEXT: 2: [B1.1] (ImplicitCastExpr, FunctionToPointerDecay, Map &(*)(const Map &))
+// CHECK-NEXT: 3: operator[]
+// CHECK-NEXT: 4: [B1.3] (ImplicitCastExpr, FunctionToPointerDecay, Map &(*)(int))
+// CHECK-NEXT: 5: m
+// CHECK-NEXT: 6: a
+// CHECK-NEXT: 7: [B1.6] (ImplicitCastExpr, LValueToRValue, int)
+// CHECK-NEXT: 8: [B1.5]{{\[\[}}B1.7]] (OperatorCall)
+// CHECK-NEXT: 9: [B1.8] (ImplicitCastExpr, NoOp, const Map)
+// CHECK-NEXT: 10: operator[]
+// CHECK-NEXT: 11: [B1.10] (ImplicitCastExpr, FunctionToPointerDecay, Map &(*)(int))
+// CHECK-NEXT: 12: m
+// CHECK-NEXT: 13: b
+// CHECK-NEXT: 14: [B1.13] (ImplicitCastExpr, LValueToRValue, int)
+// CHECK-NEXT: 15: [B1.12]{{\[\[}}B1.14]] (OperatorCall)
+// CHECK-NEXT: 16: [B1.15] = [B1.9] (OperatorCall)
+
+struct Map {
+ Map &operator[](int);
+ Map &operator=(const Map &);
+};
+
+void test_eval_order(Map &m, int a, int b) {
+ m[b] = m[a];
+}
+
+struct A {
+ A();
+ ~A();
+ A &operator=(const A &);
+};
+
+struct B {
+ B();
+ ~B();
+};
+
+struct C {
+ C();
+ ~C();
+};
+
+A &getLHS(const B &);
+A &getRHS(const C &);
+
+// CHECK-LABEL: void test_temp_dtor_order()
+// CHECK: ~B() (Temporary object destructor)
+// CHECK-NEXT: ~C() (Temporary object destructor)
+void test_temp_dtor_order() {
+ getLHS(B()) = getRHS(C());
+}
diff --git a/clang/test/Analysis/missing-bind-temporary.cpp b/clang/test/Analysis/missing-bind-temporary.cpp
index 3d1af469dc01c..2ce733b0986b0 100644
--- a/clang/test/Analysis/missing-bind-temporary.cpp
+++ b/clang/test/Analysis/missing-bind-temporary.cpp
@@ -23,11 +23,11 @@ class B {
// CHECK-NEXT: 2: B i;
// CHECK-NEXT: 3: operator=
// CHECK-NEXT: 4: [B1.3] (ImplicitCastExpr, FunctionToPointerDecay, B &(*)(B &&) noexcept)
-// CHECK-NEXT: 5: i
-// CHECK-NEXT: 6: {} (CXXConstructExpr, [B1.7], [B1.8], B)
-// CHECK-NEXT: 7: [B1.6] (BindTemporary)
-// CHECK-NEXT: 8: [B1.7]
-// CHECK-NEXT: 9: [B1.5] = [B1.8] (OperatorCall)
+// CHECK-NEXT: 5: {} (CXXConstructExpr, [B1.6], [B1.7], B)
+// CHECK-NEXT: 6: [B1.5] (BindTemporary)
+// CHECK-NEXT: 7: [B1.6]
+// CHECK-NEXT: 8: i
+// CHECK-NEXT: 9: [B1.8] = [B1.7] (OperatorCall)
// CHECK-NEXT: 10: ~B() (Temporary object destructor)
// CHECK-NEXT: 11: [B1.2].~B() (Implicit destructor)
void foo(int) {
@@ -60,13 +60,13 @@ class B {
// CHECK-NEXT: 2: B i;
// CHECK-NEXT: 3: operator=
// CHECK-NEXT: 4: [B1.3] (ImplicitCastExpr, FunctionToPointerDecay, B &(*)(B &&) noexcept)
-// CHECK-NEXT: 5: i
-// CHECK-NEXT: 6: {} (CXXConstructExpr, [B1.7], [B1.8], B)
-// CHECK-NEXT: 7: [B1.6] (BindTemporary)
-// CHECK-NEXT: 8: [B1.7]
-// CHECK-NEXT: 9: [B1.5] = [B1.8] (OperatorCall)
-// CHECK-NEXT: 10: ~B() (Temporary object destructor)
-// CHECK-NEXT: 11: [B1.2].~B() (Implicit destructor)
+// CHECK-NEXT: 5: {} (CXXConstructExpr, [B1.6], [B1.7], B)
+// CHECK-NEXT: 6: [B1.5] (BindTemporary)
+// CHECK-NEXT: 7: [B1.6]
+// CHECK-NEXT: 8: i
+// CHECK-NEXT: 9: [B1.8] = [B1.7] (OperatorCall)
+// CHECK-NEXT: 10: ~B() (Temporary object destructor)
+// CHECK-NEXT: 11: [B1.2].~B() (Implicit destructor)
template <typename T> void foo(T) {
B i;
i = {};
@@ -101,12 +101,12 @@ class B {
// CHECK-NEXT: 2: B i;
// CHECK-NEXT: 3: operator=
// CHECK-NEXT: 4: [B1.3] (ImplicitCastExpr, FunctionToPointerDecay, B &(*)(B &&) noexcept)
-// CHECK-NEXT: 5: i
+// CHECK-NEXT: 5: {}
// CHECK-NEXT: 6: {}
-// CHECK-NEXT: 7: {}
-// CHECK-NEXT: 8: [B1.7] (BindTemporary)
-// CHECK-NEXT: 9: [B1.8]
-// CHECK-NEXT: 10: [B1.5] = [B1.9] (OperatorCall)
+// CHECK-NEXT: 7: [B1.6] (BindTemporary)
+// CHECK-NEXT: 8: [B1.7]
+// CHECK-NEXT: 9: i
+// CHECK-NEXT: 10: [B1.9] = [B1.8] (OperatorCall)
// CHECK-NEXT: 11: ~B() (Temporary object destructor)
// CHECK-NEXT: 12: [B1.2].~B() (Implicit destructor)
template <typename T> void foo(T) {
diff --git a/clang/test/Analysis/scopes-cfg-output.cpp b/clang/test/Analysis/scopes-cfg-output.cpp
index 6ed6f3638f75b..ac8ff1179a994 100644
--- a/clang/test/Analysis/scopes-cfg-output.cpp
+++ b/clang/test/Analysis/scopes-cfg-output.cpp
@@ -907,10 +907,10 @@ void test_for_compound_and_break() {
// CHECK-NEXT: 5: auto &i
// CHECK-NEXT: 6: operator=
// CHECK-NEXT: 7: [B4.6] (ImplicitCastExpr, FunctionToPointerDecay, A &(*)(const A &)
-// CHECK-NEXT: 8: i
-// CHECK-NEXT: 9: b
-// CHECK-NEXT: 10: [B4.9] (ImplicitCastExpr, NoOp, const A)
-// CHECK-NEXT: 11: [B4.8] = [B4.10] (OperatorCall)
+// CHECK-NEXT: 8: b
+// CHECK-NEXT: 9: [B4.8] (ImplicitCastExpr, NoOp, const A)
+// CHECK-NEXT: 10: i
+// CHECK-NEXT: 11: [B4.10] = [B4.9] (OperatorCall)
// CHECK-NEXT: 12: CFGScopeEnd(i)
// CHECK-NEXT: Preds (1): B2
// CHECK-NEXT: Succs (1): B3
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