hazohelet created this revision.
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This patch marks the declarations with initializations in condition expressions
such as
`if (int var = init)` as unused and unreferenced so that `-Wunused` can warn on
them.
Fixes https://github.com/llvm/llvm-project/issues/61681
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D152495
Files:
clang/docs/ReleaseNotes.rst
clang/include/clang/AST/DeclBase.h
clang/lib/CodeGen/CGExpr.cpp
clang/lib/Sema/SemaExprCXX.cpp
clang/test/AST/ast-dump-if-json.cpp
clang/test/AST/ast-dump-stmt-json.cpp
clang/test/AST/ast-dump-stmt.cpp
clang/test/SemaCXX/warn-unused-variables.cpp
Index: clang/test/SemaCXX/warn-unused-variables.cpp
===================================================================
--- clang/test/SemaCXX/warn-unused-variables.cpp
+++ clang/test/SemaCXX/warn-unused-variables.cpp
@@ -1,5 +1,5 @@
// RUN: %clang_cc1 -fsyntax-only -Wunused-variable -Wunused-label -Wno-c++1y-extensions -verify %s
-// RUN: %clang_cc1 -fsyntax-only -Wunused-variable -Wunused-label -Wno-c++1y-extensions -verify -std=c++11 %s
+// RUN: %clang_cc1 -fsyntax-only -Wunused-variable -Wunused-label -Wno-c++1y-extensions -Wno-c++1z-extensions -verify -std=c++11 %s
template<typename T> void f() {
T t;
t = 17;
@@ -294,3 +294,36 @@
}
} // namespace gh54489
+
+namespace inside_condition {
+ void ifs() {
+ if (int hoge = 0) // expected-warning {{unused variable 'hoge'}}
+ return;
+ if (const int const_hoge = 0) // expected-warning {{unused variable 'const_hoge'}}
+ return;
+ else if (int fuga = 0)
+ (void)fuga;
+ else if (int used = 1; int catched = used) // expected-warning {{unused variable 'catched'}}
+ return;
+ else if (int refed = 1; int used = refed)
+ (void)used;
+ else if (int unused1 = 2; int unused2 = 3) // expected-warning {{unused variable 'unused1'}} \
+ // expected-warning {{unused variable 'unused2'}}
+ return;
+ else if (int unused = 4; int used = 5) // expected-warning {{unused variable 'unused'}}
+ (void)used;
+ else if (int used = 6; int unused = 7) // expected-warning {{unused variable 'unused'}}
+ (void)used;
+ else if (int used1 = 8; int used2 = 9)
+ (void)(used1 + used2);
+ }
+
+ void fors() {
+ for (int i = 0;int unused = 0;); // expected-warning {{unused variable 'i'}} \
+ // expected-warning {{unused variable 'unused'}}
+ for (int i = 0;int used = 0;) // expected-warning {{unused variable 'i'}}
+ (void)used;
+ while(int var = 1) // expected-warning {{unused variable 'var'}}
+ return;
+ }
+} // namespace inside_condition
Index: clang/test/AST/ast-dump-stmt.cpp
===================================================================
--- clang/test/AST/ast-dump-stmt.cpp
+++ clang/test/AST/ast-dump-stmt.cpp
@@ -179,7 +179,7 @@
// CHECK-NEXT: VarDecl 0x{{[^ ]*}} <col:8, col:16> col:12 used i 'int' cinit
// CHECK-NEXT: IntegerLiteral 0x{{[^ ]*}} <col:16> 'int' 0
// CHECK-NEXT: DeclStmt
- // CHECK-NEXT: VarDecl 0x{{[^ ]*}} <col:19, col:27> col:23 used j 'int' cinit
+ // CHECK-NEXT: VarDecl 0x{{[^ ]*}} <col:19, col:27> col:23 j 'int' cinit
// CHECK-NEXT: ImplicitCastExpr
// CHECK-NEXT: DeclRefExpr 0x{{[^ ]*}} <col:27> 'int' lvalue Var 0x{{[^ ]*}} 'i' 'int'
// CHECK-NEXT: ImplicitCastExpr 0x{{[^ ]*}} <col:23> 'bool' <IntegralToBoolean>
Index: clang/test/AST/ast-dump-stmt-json.cpp
===================================================================
--- clang/test/AST/ast-dump-stmt-json.cpp
+++ clang/test/AST/ast-dump-stmt-json.cpp
@@ -4167,7 +4167,6 @@
// CHECK-NEXT: "tokLen": 1
// CHECK-NEXT: }
// CHECK-NEXT: },
-// CHECK-NEXT: "isUsed": true,
// CHECK-NEXT: "name": "j",
// CHECK-NEXT: "type": {
// CHECK-NEXT: "qualType": "int"
Index: clang/test/AST/ast-dump-if-json.cpp
===================================================================
--- clang/test/AST/ast-dump-if-json.cpp
+++ clang/test/AST/ast-dump-if-json.cpp
@@ -709,7 +709,6 @@
// CHECK-NEXT: "tokLen": 2
// CHECK-NEXT: }
// CHECK-NEXT: },
-// CHECK-NEXT: "isUsed": true,
// CHECK-NEXT: "name": "i",
// CHECK-NEXT: "type": {
// CHECK-NEXT: "qualType": "int"
Index: clang/lib/Sema/SemaExprCXX.cpp
===================================================================
--- clang/lib/Sema/SemaExprCXX.cpp
+++ clang/lib/Sema/SemaExprCXX.cpp
@@ -3998,6 +3998,11 @@
ConditionVar, ConditionVar->getType().getNonReferenceType(), VK_LValue,
ConditionVar->getLocation());
+ // Ensure that `-Wunused-variable` will be emitted for condition variables
+ // that are not referenced or used later. e.g.: if (int var = init());
+ ConditionVar->setReferenced(false);
+ ConditionVar->setIsUsed(false);
+
switch (CK) {
case ConditionKind::Boolean:
return CheckBooleanCondition(StmtLoc, Condition.get());
Index: clang/lib/CodeGen/CGExpr.cpp
===================================================================
--- clang/lib/CodeGen/CGExpr.cpp
+++ clang/lib/CodeGen/CGExpr.cpp
@@ -2843,13 +2843,6 @@
}
}
- // FIXME: We should be able to assert this for FunctionDecls as well!
- // FIXME: We should be able to assert this for all DeclRefExprs, not just
- // those with a valid source location.
- assert((ND->isUsed(false) || !isa<VarDecl>(ND) || E->isNonOdrUse() ||
- !E->getLocation().isValid()) &&
- "Should not use decl without marking it used!");
-
if (ND->hasAttr<WeakRefAttr>()) {
const auto *VD = cast<ValueDecl>(ND);
ConstantAddress Aliasee = CGM.GetWeakRefReference(VD);
Index: clang/include/clang/AST/DeclBase.h
===================================================================
--- clang/include/clang/AST/DeclBase.h
+++ clang/include/clang/AST/DeclBase.h
@@ -588,7 +588,7 @@
///
/// This should only be used immediately after creating a declaration.
/// It intentionally doesn't notify any listeners.
- void setIsUsed() { getCanonicalDecl()->Used = true; }
+ void setIsUsed(bool U = true) { getCanonicalDecl()->Used = U; }
/// Mark the declaration used, in the sense of odr-use.
///
Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -337,6 +337,10 @@
can be controlled using ``-fcaret-diagnostics-max-lines=``.
- Clang no longer emits ``-Wunused-variable`` warnings for variables declared
with ``__attribute__((cleanup(...)))`` to match GCC's behavior.
+- Clang now warns on unused variables declaread and initialized in condition
+ expressions.
+ (`#61681: <https://github.com/llvm/llvm-project/issues/61681>`_)
+
Bug Fixes in This Version
-------------------------
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