Merge pull request #8554 from jketema/bitwise-lambda-capture-init

C++: Handle bitwise copies in lambda captures

Author: jketema

cpp/ql/src/Best Practices/Unused Entities/UnusedLocals.ql

@@ -58,11 +58,5 @@ where
   not exists(AsmStmt s | f = s.getEnclosingFunction()) and
   not v.getAnAttribute().getName() = "unused" and
   not any(ErrorExpr e).getEnclosingFunction() = f and // unextracted expr may use `v`
-  not exists(
-    Literal l // this case can be removed when the `myFunction2( [obj](){} );` test case doesn't depend on this exclusion
-  |
-    l.getEnclosingFunction() = f and
-    not exists(l.getValue())
-  ) and
   not any(ConditionDeclExpr cde).getEnclosingFunction() = f // this case can be removed when the `if (a = b; a)` test case doesn't depend on this exclusion
 select v, "Variable " + v.getName() + " is not used"

cpp/ql/src/change-notes/2022-03-25-unused-lambda-capture.md

@@ -0,0 +1,4 @@
+---
+category: minorAnalysis
+---
+* The `cpp/unused-local-variable` no longer ignores functions that include lambda expressions capturing trivially copyable objects.

cpp/ql/test/library-tests/ir/ir/PrintAST.expected

@@ -6,8 +6,6 @@ missingOperandType
 duplicateChiOperand
 sideEffectWithoutPrimary
 instructionWithoutSuccessor
-| ir.cpp:1688:24:1690:5 | FieldAddress: {...} | Instruction 'FieldAddress: {...}' has no successors in function '$@'. | ir.cpp:1683:6:1683:20 | void captured_lambda(int, int&, int&&) | void captured_lambda(int, int&, int&&) |
-| ir.cpp:1689:28:1689:54 | FieldAddress: {...} | Instruction 'FieldAddress: {...}' has no successors in function '$@'. | ir.cpp:1688:46:1688:46 | void (void captured_lambda(int, int&, int&&))::(lambda [] type at line 1688, col. 25)::operator()() const | void (void captured_lambda(int, int&, int&&))::(lambda [] type at line 1688, col. 25)::operator()() const |
 ambiguousSuccessors
 unexplainedLoop
 unnecessaryPhiInstruction

cpp/ql/test/library-tests/ir/ir/aliased_ssa_consistency.expected

@@ -6,8 +6,6 @@ missingOperandType
 duplicateChiOperand
 sideEffectWithoutPrimary
 instructionWithoutSuccessor
-| ir.cpp:1688:24:1690:5 | FieldAddress: {...} | Instruction 'FieldAddress: {...}' has no successors in function '$@'. | ir.cpp:1683:6:1683:20 | void captured_lambda(int, int&, int&&) | void captured_lambda(int, int&, int&&) |
-| ir.cpp:1689:28:1689:54 | FieldAddress: {...} | Instruction 'FieldAddress: {...}' has no successors in function '$@'. | ir.cpp:1688:46:1688:46 | void (void captured_lambda(int, int&, int&&))::(lambda [] type at line 1688, col. 25)::operator()() const | void (void captured_lambda(int, int&, int&&))::(lambda [] type at line 1688, col. 25)::operator()() const |
 ambiguousSuccessors
 unexplainedLoop
 unnecessaryPhiInstruction

cpp/ql/test/library-tests/ir/ir/aliased_ssa_consistency_unsound.expected

@@ -1696,4 +1696,26 @@ int goto_on_same_line() {
   return x;
 }
 
+class TrivialLambdaClass {
+public:
+    void m() const {
+        auto l_m_outer = [*this] {
+            m();
+
+            auto l_m_inner = [*this] {
+                m();
+            };
+        };
+    };
+};
+
+void captured_lambda2(TrivialLambdaClass p1, TrivialLambdaClass &p2, TrivialLambdaClass &&p3) {
+    const TrivialLambdaClass l1;
+    const TrivialLambdaClass &l2 = TrivialLambdaClass();
+
+    auto l_outer1 = [p1, p2, p3, l1, l2] {
+        auto l_inner1 = [p1] {};
+    };
+}
+
 // semmle-extractor-options: -std=c++17 --clang

cpp/ql/test/library-tests/ir/ir/ir.cpp

@@ -1,8 +1,4 @@
 missingOperand
-| ir.cpp:1688:24:1690:5 | Store: Unknown literal | Instruction 'Store' is missing an expected operand with tag 'StoreValue' in function '$@'. | ir.cpp:1683:6:1683:20 | void captured_lambda(int, int&, int&&) | void captured_lambda(int, int&, int&&) |
-| ir.cpp:1688:24:1690:5 | Store: Unknown literal | Instruction 'Store' is missing an expected operand with tag 'StoreValue' in function '$@'. | ir.cpp:1683:6:1683:20 | void captured_lambda(int, int&, int&&) | void captured_lambda(int, int&, int&&) |
-| ir.cpp:1689:28:1689:54 | Store: Unknown literal | Instruction 'Store' is missing an expected operand with tag 'StoreValue' in function '$@'. | ir.cpp:1688:46:1688:46 | void (void captured_lambda(int, int&, int&&))::(lambda [] type at line 1688, col. 25)::operator()() const | void (void captured_lambda(int, int&, int&&))::(lambda [] type at line 1688, col. 25)::operator()() const |
-| ir.cpp:1689:28:1689:54 | Store: Unknown literal | Instruction 'Store' is missing an expected operand with tag 'StoreValue' in function '$@'. | ir.cpp:1688:46:1688:46 | void (void captured_lambda(int, int&, int&&))::(lambda [] type at line 1688, col. 25)::operator()() const | void (void captured_lambda(int, int&, int&&))::(lambda [] type at line 1688, col. 25)::operator()() const |
 unexpectedOperand
 duplicateOperand
 missingPhiOperand
@@ -11,10 +7,6 @@ duplicateChiOperand
 sideEffectWithoutPrimary
 instructionWithoutSuccessor
 | ../../../include/memory.h:68:25:68:33 | CopyValue: (reference to) | Instruction 'CopyValue: (reference to)' has no successors in function '$@'. | ../../../include/memory.h:67:5:67:5 | void std::unique_ptr<int, std::default_delete<int>>::~unique_ptr() | void std::unique_ptr<int, std::default_delete<int>>::~unique_ptr() |
-| ir.cpp:1688:24:1690:5 | FieldAddress: {...} | Instruction 'FieldAddress: {...}' has no successors in function '$@'. | ir.cpp:1683:6:1683:20 | void captured_lambda(int, int&, int&&) | void captured_lambda(int, int&, int&&) |
-| ir.cpp:1688:24:1690:5 | FieldAddress: {...} | Instruction 'FieldAddress: {...}' has no successors in function '$@'. | ir.cpp:1683:6:1683:20 | void captured_lambda(int, int&, int&&) | void captured_lambda(int, int&, int&&) |
-| ir.cpp:1689:28:1689:54 | FieldAddress: {...} | Instruction 'FieldAddress: {...}' has no successors in function '$@'. | ir.cpp:1688:46:1688:46 | void (void captured_lambda(int, int&, int&&))::(lambda [] type at line 1688, col. 25)::operator()() const | void (void captured_lambda(int, int&, int&&))::(lambda [] type at line 1688, col. 25)::operator()() const |
-| ir.cpp:1689:28:1689:54 | FieldAddress: {...} | Instruction 'FieldAddress: {...}' has no successors in function '$@'. | ir.cpp:1688:46:1688:46 | void (void captured_lambda(int, int&, int&&))::(lambda [] type at line 1688, col. 25)::operator()() const | void (void captured_lambda(int, int&, int&&))::(lambda [] type at line 1688, col. 25)::operator()() const |
 ambiguousSuccessors
 unexplainedLoop
 unnecessaryPhiInstruction
@@ -26,25 +18,6 @@ lostReachability
 backEdgeCountMismatch
 useNotDominatedByDefinition
 | ir.cpp:1486:8:1486:8 | Unary | Operand 'Unary' is not dominated by its definition in function '$@'. | ir.cpp:1486:8:1486:8 | void StructuredBindingDataMemberStruct::StructuredBindingDataMemberStruct() | void StructuredBindingDataMemberStruct::StructuredBindingDataMemberStruct() |
-| ir.cpp:1683:34:1683:34 | Address | Operand 'Address' is not dominated by its definition in function '$@'. | ir.cpp:1683:6:1683:20 | void captured_lambda(int, int&, int&&) | void captured_lambda(int, int&, int&&) |
-| ir.cpp:1683:43:1683:43 | Address | Operand 'Address' is not dominated by its definition in function '$@'. | ir.cpp:1683:6:1683:20 | void captured_lambda(int, int&, int&&) | void captured_lambda(int, int&, int&&) |
-| ir.cpp:1688:10:1688:21 | Address | Operand 'Address' is not dominated by its definition in function '$@'. | ir.cpp:1683:6:1683:20 | void captured_lambda(int, int&, int&&) | void captured_lambda(int, int&, int&&) |
-| ir.cpp:1688:24:1690:5 | Address | Operand 'Address' is not dominated by its definition in function '$@'. | ir.cpp:1683:6:1683:20 | void captured_lambda(int, int&, int&&) | void captured_lambda(int, int&, int&&) |
-| ir.cpp:1688:24:1690:5 | Address | Operand 'Address' is not dominated by its definition in function '$@'. | ir.cpp:1683:6:1683:20 | void captured_lambda(int, int&, int&&) | void captured_lambda(int, int&, int&&) |
-| ir.cpp:1688:24:1690:5 | Address | Operand 'Address' is not dominated by its definition in function '$@'. | ir.cpp:1683:6:1683:20 | void captured_lambda(int, int&, int&&) | void captured_lambda(int, int&, int&&) |
-| ir.cpp:1688:24:1690:5 | Unary | Operand 'Unary' is not dominated by its definition in function '$@'. | ir.cpp:1683:6:1683:20 | void captured_lambda(int, int&, int&&) | void captured_lambda(int, int&, int&&) |
-| ir.cpp:1688:24:1690:5 | Unary | Operand 'Unary' is not dominated by its definition in function '$@'. | ir.cpp:1683:6:1683:20 | void captured_lambda(int, int&, int&&) | void captured_lambda(int, int&, int&&) |
-| ir.cpp:1688:24:1690:5 | Unary | Operand 'Unary' is not dominated by its definition in function '$@'. | ir.cpp:1683:6:1683:20 | void captured_lambda(int, int&, int&&) | void captured_lambda(int, int&, int&&) |
-| ir.cpp:1688:24:1690:5 | Unary | Operand 'Unary' is not dominated by its definition in function '$@'. | ir.cpp:1683:6:1683:20 | void captured_lambda(int, int&, int&&) | void captured_lambda(int, int&, int&&) |
-| ir.cpp:1688:46:1688:46 | Address | Operand 'Address' is not dominated by its definition in function '$@'. | ir.cpp:1688:46:1688:46 | void (void captured_lambda(int, int&, int&&))::(lambda [] type at line 1688, col. 25)::operator()() const | void (void captured_lambda(int, int&, int&&))::(lambda [] type at line 1688, col. 25)::operator()() const |
-| ir.cpp:1689:14:1689:25 | Address | Operand 'Address' is not dominated by its definition in function '$@'. | ir.cpp:1688:46:1688:46 | void (void captured_lambda(int, int&, int&&))::(lambda [] type at line 1688, col. 25)::operator()() const | void (void captured_lambda(int, int&, int&&))::(lambda [] type at line 1688, col. 25)::operator()() const |
-| ir.cpp:1689:28:1689:54 | Address | Operand 'Address' is not dominated by its definition in function '$@'. | ir.cpp:1688:46:1688:46 | void (void captured_lambda(int, int&, int&&))::(lambda [] type at line 1688, col. 25)::operator()() const | void (void captured_lambda(int, int&, int&&))::(lambda [] type at line 1688, col. 25)::operator()() const |
-| ir.cpp:1689:28:1689:54 | Address | Operand 'Address' is not dominated by its definition in function '$@'. | ir.cpp:1688:46:1688:46 | void (void captured_lambda(int, int&, int&&))::(lambda [] type at line 1688, col. 25)::operator()() const | void (void captured_lambda(int, int&, int&&))::(lambda [] type at line 1688, col. 25)::operator()() const |
-| ir.cpp:1689:28:1689:54 | Address | Operand 'Address' is not dominated by its definition in function '$@'. | ir.cpp:1688:46:1688:46 | void (void captured_lambda(int, int&, int&&))::(lambda [] type at line 1688, col. 25)::operator()() const | void (void captured_lambda(int, int&, int&&))::(lambda [] type at line 1688, col. 25)::operator()() const |
-| ir.cpp:1689:28:1689:54 | Unary | Operand 'Unary' is not dominated by its definition in function '$@'. | ir.cpp:1688:46:1688:46 | void (void captured_lambda(int, int&, int&&))::(lambda [] type at line 1688, col. 25)::operator()() const | void (void captured_lambda(int, int&, int&&))::(lambda [] type at line 1688, col. 25)::operator()() const |
-| ir.cpp:1689:28:1689:54 | Unary | Operand 'Unary' is not dominated by its definition in function '$@'. | ir.cpp:1688:46:1688:46 | void (void captured_lambda(int, int&, int&&))::(lambda [] type at line 1688, col. 25)::operator()() const | void (void captured_lambda(int, int&, int&&))::(lambda [] type at line 1688, col. 25)::operator()() const |
-| ir.cpp:1689:28:1689:54 | Unary | Operand 'Unary' is not dominated by its definition in function '$@'. | ir.cpp:1688:46:1688:46 | void (void captured_lambda(int, int&, int&&))::(lambda [] type at line 1688, col. 25)::operator()() const | void (void captured_lambda(int, int&, int&&))::(lambda [] type at line 1688, col. 25)::operator()() const |
-| ir.cpp:1689:28:1689:54 | Unary | Operand 'Unary' is not dominated by its definition in function '$@'. | ir.cpp:1688:46:1688:46 | void (void captured_lambda(int, int&, int&&))::(lambda [] type at line 1688, col. 25)::operator()() const | void (void captured_lambda(int, int&, int&&))::(lambda [] type at line 1688, col. 25)::operator()() const |
 switchInstructionWithoutDefaultEdge
 notMarkedAsConflated
 wronglyMarkedAsConflated