Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -381,6 +381,9 @@
   (`#57081: <https://github.com/llvm/llvm-project/issues/57081>`_)
 - Clang no longer emits inappropriate notes about the loss of ``__unaligned`` qualifier
   on overload resolution, when the actual reason for the failure is loss of other qualifiers.
+- Clang now warns on unused variables of non-aggregate types declared and initialized
+  in condition expressions.
+  (`#61681: <https://github.com/llvm/llvm-project/issues/61681>`_)
 
 Bug Fixes in This Version
 -------------------------
Index: clang/lib/Sema/SemaDecl.cpp
===================================================================
--- clang/lib/Sema/SemaDecl.cpp
+++ clang/lib/Sema/SemaDecl.cpp
@@ -1989,7 +1989,7 @@
         return false;
   } else if (!D->getDeclName()) {
     return false;
-  } else if (D->isReferenced() || D->isUsed()) {
+  } else if (D->isReferenced() || (!isa<VarDecl>(D) && D->isUsed())) {
     return false;
   }
 
Index: clang/lib/Sema/SemaExprCXX.cpp
===================================================================
--- clang/lib/Sema/SemaExprCXX.cpp
+++ clang/lib/Sema/SemaExprCXX.cpp
@@ -4013,6 +4013,11 @@
       ConditionVar, ConditionVar->getType().getNonReferenceType(), VK_LValue,
       ConditionVar->getLocation());
 
+  // Ensure that `-Wunused-variable` will be emitted for condition variables
+  // that are not referenced later. e.g.: if (int var = init());
+  if (!T->isAggregateType())
+    ConditionVar->setReferenced(/*R=*/false);
+
   switch (CK) {
   case ConditionKind::Boolean:
     return CheckBooleanCondition(StmtLoc, Condition.get());
Index: clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
===================================================================
--- clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -5345,7 +5345,7 @@
   // will have been deferred.
   if (!NewVar->isInvalidDecl() &&
       NewVar->getDeclContext()->isFunctionOrMethod() &&
-      OldVar->getType()->isDependentType())
+      OldVar->getType()->isDependentType() && !OldVar->isImplicit())
     DiagnoseUnusedDecl(NewVar);
 }
 
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 +294,49 @@
 }
 
 } // 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;
+  }
+
+  struct RAII {
+    int &x;
+    RAII(int &ref) : x(ref) {}
+    ~RAII() { x = 0;}
+    operator bool() const { return true; }
+  };
+  void aggregate() {
+    int x = 10;
+    if (RAII var = x) {}
+  }
+
+
+} // namespace inside_condition