r314733 - PR33839: Fix -Wunused handling for structured binding declarations.
Richard Smith via cfe-commits
cfe-commits at lists.llvm.org
Mon Oct 2 15:43:37 PDT 2017
Author: rsmith
Date: Mon Oct 2 15:43:36 2017
New Revision: 314733
URL: http://llvm.org/viewvc/llvm-project?rev=314733&view=rev
Log:
PR33839: Fix -Wunused handling for structured binding declarations.
We warn about a structured binding declaration being unused only if none of its
bindings are used.
Modified:
cfe/trunk/lib/Sema/SemaDecl.cpp
cfe/trunk/lib/Sema/SemaDeclCXX.cpp
cfe/trunk/lib/Sema/SemaTemplateInstantiateDecl.cpp
cfe/trunk/test/SemaCXX/unused.cpp
Modified: cfe/trunk/lib/Sema/SemaDecl.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaDecl.cpp?rev=314733&r1=314732&r2=314733&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaDecl.cpp (original)
+++ cfe/trunk/lib/Sema/SemaDecl.cpp Mon Oct 2 15:43:36 2017
@@ -1604,7 +1604,24 @@ static bool ShouldDiagnoseUnusedDecl(con
if (D->isInvalidDecl())
return false;
- if (D->isReferenced() || D->isUsed() || D->hasAttr<UnusedAttr>() ||
+ bool Referenced = false;
+ if (auto *DD = dyn_cast<DecompositionDecl>(D)) {
+ // For a decomposition declaration, warn if none of the bindings are
+ // referenced, instead of if the variable itself is referenced (which
+ // it is, by the bindings' expressions).
+ for (auto *BD : DD->bindings()) {
+ if (BD->isReferenced()) {
+ Referenced = true;
+ break;
+ }
+ }
+ } else if (!D->getDeclName()) {
+ return false;
+ } else if (D->isReferenced() || D->isUsed()) {
+ Referenced = true;
+ }
+
+ if (Referenced || D->hasAttr<UnusedAttr>() ||
D->hasAttr<ObjCPreciseLifetimeAttr>())
return false;
@@ -1727,7 +1744,7 @@ void Sema::DiagnoseUnusedDecl(const Name
else
DiagID = diag::warn_unused_variable;
- Diag(D->getLocation(), DiagID) << D->getDeclName() << Hint;
+ Diag(D->getLocation(), DiagID) << D << Hint;
}
static void CheckPoppedLabel(LabelDecl *L, Sema &S) {
@@ -1757,8 +1774,6 @@ void Sema::ActOnPopScope(SourceLocation
assert(isa<NamedDecl>(TmpD) && "Decl isn't NamedDecl?");
NamedDecl *D = cast<NamedDecl>(TmpD);
- if (!D->getDeclName()) continue;
-
// Diagnose unused variables in this scope.
if (!S->hasUnrecoverableErrorOccurred()) {
DiagnoseUnusedDecl(D);
@@ -1766,6 +1781,8 @@ void Sema::ActOnPopScope(SourceLocation
DiagnoseUnusedNestedTypedefs(RD);
}
+ if (!D->getDeclName()) continue;
+
// If this was a forward reference to a label, verify it was defined.
if (LabelDecl *LD = dyn_cast<LabelDecl>(D))
CheckPoppedLabel(LD, *this);
@@ -6164,7 +6181,6 @@ NamedDecl *Sema::ActOnVariableDeclarator
IdentifierInfo *II = Name.getAsIdentifierInfo();
if (D.isDecompositionDeclarator()) {
- AddToScope = false;
// Take the name of the first declarator as our name for diagnostic
// purposes.
auto &Decomp = D.getDecompositionDeclarator();
Modified: cfe/trunk/lib/Sema/SemaDeclCXX.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaDeclCXX.cpp?rev=314733&r1=314732&r2=314733&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaDeclCXX.cpp (original)
+++ cfe/trunk/lib/Sema/SemaDeclCXX.cpp Mon Oct 2 15:43:36 2017
@@ -829,7 +829,10 @@ Sema::ActOnDecompositionDeclarator(Scope
NamedDecl *New =
ActOnVariableDeclarator(S, D, DC, TInfo, Previous,
MultiTemplateParamsArg(), AddToScope, Bindings);
- CurContext->addHiddenDecl(New);
+ if (AddToScope) {
+ S->AddDecl(New);
+ CurContext->addHiddenDecl(New);
+ }
if (isInOpenMPDeclareTargetContext())
checkDeclIsAllowedInOpenMPTarget(nullptr, New);
Modified: cfe/trunk/lib/Sema/SemaTemplateInstantiateDecl.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaTemplateInstantiateDecl.cpp?rev=314733&r1=314732&r2=314733&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaTemplateInstantiateDecl.cpp (original)
+++ cfe/trunk/lib/Sema/SemaTemplateInstantiateDecl.cpp Mon Oct 2 15:43:36 2017
@@ -677,6 +677,7 @@ TemplateDeclInstantiator::VisitTypeAlias
Decl *TemplateDeclInstantiator::VisitBindingDecl(BindingDecl *D) {
auto *NewBD = BindingDecl::Create(SemaRef.Context, Owner, D->getLocation(),
D->getIdentifier());
+ NewBD->setReferenced(D->isReferenced());
SemaRef.CurrentInstantiationScope->InstantiatedLocal(D, NewBD);
return NewBD;
}
Modified: cfe/trunk/test/SemaCXX/unused.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/unused.cpp?rev=314733&r1=314732&r2=314733&view=diff
==============================================================================
--- cfe/trunk/test/SemaCXX/unused.cpp (original)
+++ cfe/trunk/test/SemaCXX/unused.cpp Mon Oct 2 15:43:36 2017
@@ -1,6 +1,7 @@
-// RUN: %clang_cc1 -fsyntax-only -verify %s
-// RUN: %clang_cc1 -fsyntax-only -verify -std=c++98 %s
-// RUN: %clang_cc1 -fsyntax-only -verify -std=c++11 %s
+// RUN: %clang_cc1 -fsyntax-only -verify -Wunused %s
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++98 -Wunused %s
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++11 -Wunused %s
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++17 -Wunused %s
// PR4103 : Make sure we don't get a bogus unused expression warning
namespace PR4103 {
@@ -8,7 +9,7 @@ namespace PR4103 {
char foo;
};
class APSInt : public APInt {
- char bar;
+ char bar; // expected-warning {{private field 'bar' is not used}}
public:
APSInt &operator=(const APSInt &RHS);
};
@@ -69,3 +70,44 @@ namespace UnresolvedLookup {
}
};
}
+
+#if __cplusplus >= 201703L
+namespace PR33839 {
+ void a() {
+ struct X { int a, b; } x;
+ auto [a, b] = x; // expected-warning {{unused variable '[a, b]'}}
+ auto [c, d] = x;
+ (void)d;
+ }
+
+ template<typename T> void f() {
+ struct A { int n; } a[1];
+ for (auto [x] : a) {
+ (void)x;
+ }
+ auto [y] = a[0]; // expected-warning {{unused}}
+ }
+ template<bool b> void g() {
+ struct A { int n; } a[1];
+ for (auto [x] : a) {
+ if constexpr (b)
+ (void)x;
+ }
+
+ auto [y] = a[0];
+ if constexpr (b)
+ (void)y; // ok, even when b == false
+ }
+ template<typename T> void h() {
+ struct A { int n; } a[1];
+ for (auto [x] : a) { // expected-warning {{unused variable '[x]'}}
+ }
+ }
+ void use() {
+ f<int>(); // expected-note {{instantiation of}}
+ g<true>();
+ g<false>();
+ h<int>(); // expected-note {{instantiation of}}
+ }
+}
+#endif
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