diff --git a/clang/include/clang/AST/Decl.h b/clang/include/clang/AST/Decl.h
--- a/clang/include/clang/AST/Decl.h
+++ b/clang/include/clang/AST/Decl.h
@@ -695,6 +695,8 @@
   }
 };
 
+class VarDecl;
+
 /// Represent the declaration of a variable (in which case it is
 /// an lvalue) a function (in which case it is a function designator) or
 /// an enum constant.
@@ -721,6 +723,13 @@
   /// can be captured.
   bool isInitCapture() const;
 
+  // If this is a VarDecl, or a BindindDecl with an
+  // associated decomposed VarDecl, return that VarDecl.
+  VarDecl *getPotentiallyDecomposedVarDecl();
+  const VarDecl *getPotentiallyDecomposedVarDecl() const {
+    return const_cast<ValueDecl *>(this)->getPotentiallyDecomposedVarDecl();
+  }
+
   // Implement isa/cast/dyncast/etc.
   static bool classof(const Decl *D) { return classofKind(D->getKind()); }
   static bool classofKind(Kind K) { return K >= firstValue && K <= lastValue; }
diff --git a/clang/include/clang/Sema/ScopeInfo.h b/clang/include/clang/Sema/ScopeInfo.h
--- a/clang/include/clang/Sema/ScopeInfo.h
+++ b/clang/include/clang/Sema/ScopeInfo.h
@@ -1028,7 +1028,7 @@
   }
 
   void visitPotentialCaptures(
-      llvm::function_ref<void(VarDecl *, Expr *)> Callback) const;
+      llvm::function_ref<void(ValueDecl *, Expr *)> Callback) const;
 };
 
 FunctionScopeInfo::WeakObjectProfileTy::WeakObjectProfileTy()
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -5409,7 +5409,7 @@
   void MarkDeclRefReferenced(DeclRefExpr *E, const Expr *Base = nullptr);
   void MarkMemberReferenced(MemberExpr *E);
   void MarkFunctionParmPackReferenced(FunctionParmPackExpr *E);
-  void MarkCaptureUsedInEnclosingContext(VarDecl *Capture, SourceLocation Loc,
+  void MarkCaptureUsedInEnclosingContext(ValueDecl *Capture, SourceLocation Loc,
                                          unsigned CapturingScopeIndex);
 
   ExprResult CheckLValueToRValueConversionOperand(Expr *E);
diff --git a/clang/include/clang/Sema/SemaLambda.h b/clang/include/clang/Sema/SemaLambda.h
--- a/clang/include/clang/Sema/SemaLambda.h
+++ b/clang/include/clang/Sema/SemaLambda.h
@@ -32,7 +32,7 @@
 
 Optional<unsigned> getStackIndexOfNearestEnclosingCaptureCapableLambda(
     ArrayRef<const sema::FunctionScopeInfo *> FunctionScopes,
-    VarDecl *VarToCapture, Sema &S);
+    ValueDecl *VarToCapture, Sema &S);
 
 } // clang
 
diff --git a/clang/lib/AST/DeclCXX.cpp b/clang/lib/AST/DeclCXX.cpp
--- a/clang/lib/AST/DeclCXX.cpp
+++ b/clang/lib/AST/DeclCXX.cpp
@@ -3249,6 +3249,16 @@
                                       nullptr, SourceLocation(), false);
 }
 
+VarDecl *ValueDecl::getPotentiallyDecomposedVarDecl() {
+  assert((isa<VarDecl, BindingDecl>(this)) &&
+         "expected a VarDecl or a BindingDecl");
+  if (auto *Var = llvm::dyn_cast<VarDecl>(this))
+    return Var;
+  if (auto *BD = llvm::dyn_cast<BindingDecl>(this))
+    return llvm::dyn_cast<VarDecl>(BD->getDecomposedDecl());
+  return nullptr;
+}
+
 void BindingDecl::anchor() {}
 
 BindingDecl *BindingDecl::Create(ASTContext &C, DeclContext *DC,
diff --git a/clang/lib/Sema/ScopeInfo.cpp b/clang/lib/Sema/ScopeInfo.cpp
--- a/clang/lib/Sema/ScopeInfo.cpp
+++ b/clang/lib/Sema/ScopeInfo.cpp
@@ -231,14 +231,14 @@
 }
 
 void LambdaScopeInfo::visitPotentialCaptures(
-    llvm::function_ref<void(VarDecl *, Expr *)> Callback) const {
+    llvm::function_ref<void(ValueDecl *, Expr *)> Callback) const {
   for (Expr *E : PotentiallyCapturingExprs) {
     if (auto *DRE = dyn_cast<DeclRefExpr>(E)) {
-      Callback(cast<VarDecl>(DRE->getFoundDecl()), E);
+      Callback(cast<ValueDecl>(DRE->getFoundDecl()), E);
     } else if (auto *ME = dyn_cast<MemberExpr>(E)) {
-      Callback(cast<VarDecl>(ME->getMemberDecl()), E);
+      Callback(cast<ValueDecl>(ME->getMemberDecl()), E);
     } else if (auto *FP = dyn_cast<FunctionParmPackExpr>(E)) {
-      for (VarDecl *VD : *FP)
+      for (ValueDecl *VD : *FP)
         Callback(VD, E);
     } else {
       llvm_unreachable("unexpected expression in potential captures list");
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -88,7 +88,11 @@
 /// determine whether this declaration can be used in the default
 /// argument expression.
 bool CheckDefaultArgumentVisitor::VisitDeclRefExpr(const DeclRefExpr *DRE) {
-  const NamedDecl *Decl = DRE->getDecl();
+  const ValueDecl *Decl = dyn_cast<ValueDecl>(DRE->getDecl());
+
+  if (!isa<VarDecl, BindingDecl>(Decl))
+    return false;
+
   if (const auto *Param = dyn_cast<ParmVarDecl>(Decl)) {
     // C++ [dcl.fct.default]p9:
     //   [...] parameters of a function shall not be used in default
@@ -102,30 +106,23 @@
       return S.Diag(DRE->getBeginLoc(),
                     diag::err_param_default_argument_references_param)
              << Param->getDeclName() << DefaultArg->getSourceRange();
-  } else {
-    const VarDecl *VD = nullptr;
-    if (const auto *BD = dyn_cast<BindingDecl>(Decl))
-      VD = dyn_cast_if_present<VarDecl>(BD->getDecomposedDecl());
-    else
-      VD = dyn_cast<VarDecl>(Decl);
-    if (VD) {
-      // C++ [dcl.fct.default]p7:
-      //   Local variables shall not be used in default argument
-      //   expressions.
-      //
-      // C++17 [dcl.fct.default]p7 (by CWG 2082):
-      //   A local variable shall not appear as a potentially-evaluated
-      //   expression in a default argument.
-      //
-      // C++20 [dcl.fct.default]p7 (DR as part of P0588R1, see also CWG 2346):
-      //   Note: A local variable cannot be odr-used (6.3) in a default
-      //   argument.
-      //
-      if (VD->isLocalVarDecl() && !DRE->isNonOdrUse())
-        return S.Diag(DRE->getBeginLoc(),
-                      diag::err_param_default_argument_references_local)
-               << Decl->getDeclName() << DefaultArg->getSourceRange();
-    }
+  } else if (auto *VD = Decl->getPotentiallyDecomposedVarDecl()) {
+    // C++ [dcl.fct.default]p7:
+    //   Local variables shall not be used in default argument
+    //   expressions.
+    //
+    // C++17 [dcl.fct.default]p7 (by CWG 2082):
+    //   A local variable shall not appear as a potentially-evaluated
+    //   expression in a default argument.
+    //
+    // C++20 [dcl.fct.default]p7 (DR as part of P0588R1, see also CWG 2346):
+    //   Note: A local variable cannot be odr-used (6.3) in a default
+    //   argument.
+    //
+    if (VD->isLocalVarDecl() && !DRE->isNonOdrUse())
+      return S.Diag(DRE->getBeginLoc(),
+                    diag::err_param_default_argument_references_local)
+             << Decl << DefaultArg->getSourceRange();
   }
   return false;
 }
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -18482,10 +18482,13 @@
 ///  - else capture it in the DeclContext that maps to the
 ///    *FunctionScopeIndexToStopAt on the FunctionScopeInfo stack.
 static void
-MarkVarDeclODRUsed(VarDecl *Var, SourceLocation Loc, Sema &SemaRef,
+MarkVarDeclODRUsed(ValueDecl *V, SourceLocation Loc, Sema &SemaRef,
                    const unsigned *const FunctionScopeIndexToStopAt = nullptr) {
   // Keep track of used but undefined variables.
   // FIXME: We shouldn't suppress this warning for static data members.
+  VarDecl *Var = V->getPotentiallyDecomposedVarDecl();
+  assert(Var && "expected a capturable variable");
+
   if (Var->hasDefinition(SemaRef.Context) == VarDecl::DeclarationOnly &&
       (!Var->isExternallyVisible() || Var->isInline() ||
        SemaRef.isExternalWithNoLinkageType(Var)) &&
@@ -18496,12 +18499,11 @@
   }
   QualType CaptureType, DeclRefType;
   if (SemaRef.LangOpts.OpenMP)
-    SemaRef.tryCaptureOpenMPLambdas(Var);
-  SemaRef.tryCaptureVariable(Var, Loc, Sema::TryCapture_Implicit,
-    /*EllipsisLoc*/ SourceLocation(),
-    /*BuildAndDiagnose*/ true,
-    CaptureType, DeclRefType,
-    FunctionScopeIndexToStopAt);
+    SemaRef.tryCaptureOpenMPLambdas(V);
+  SemaRef.tryCaptureVariable(V, Loc, Sema::TryCapture_Implicit,
+                             /*EllipsisLoc*/ SourceLocation(),
+                             /*BuildAndDiagnose*/ true, CaptureType,
+                             DeclRefType, FunctionScopeIndexToStopAt);
 
   if (SemaRef.LangOpts.CUDA && Var->hasGlobalStorage()) {
     auto *FD = dyn_cast_or_null<FunctionDecl>(SemaRef.CurContext);
@@ -18541,10 +18543,10 @@
     }
   }
 
-  Var->markUsed(SemaRef.Context);
+  V->markUsed(SemaRef.Context);
 }
 
-void Sema::MarkCaptureUsedInEnclosingContext(VarDecl *Capture,
+void Sema::MarkCaptureUsedInEnclosingContext(ValueDecl *Capture,
                                              SourceLocation Loc,
                                              unsigned CapturingScopeIndex) {
   MarkVarDeclODRUsed(Capture, Loc, *this, &CapturingScopeIndex);
@@ -18631,13 +18633,9 @@
   if (isa<BlockDecl>(DC) || isa<CapturedDecl>(DC) || isLambdaCallOperator(DC))
     return getLambdaAwareParentOfDeclContext(DC);
 
-  ValueDecl *Underlying = Var;
-  auto *BD = dyn_cast_or_null<BindingDecl>(Var);
-  if (BD)
-    Underlying = BD->getDecomposedDecl();
-
-  if (auto *VD = dyn_cast<VarDecl>(Underlying)) {
-    if (VD->hasLocalStorage() && Diagnose)
+  VarDecl *Underlying = Var->getPotentiallyDecomposedVarDecl();
+  if (Underlying) {
+    if (Underlying->hasLocalStorage() && Diagnose)
       diagnoseUncapturableValueReferenceOrBinding(S, Loc, Var);
   }
   return nullptr;
@@ -19053,8 +19051,7 @@
     if (VD->isInitCapture())
       VarDC = VarDC->getParent();
   } else {
-    VD = dyn_cast<DecompositionDecl>(
-        cast<BindingDecl>(Var)->getDecomposedDecl());
+    VD = Var->getPotentiallyDecomposedVarDecl();
   }
   assert(VD && "Cannot capture a null variable");
 
@@ -19728,6 +19725,38 @@
          "MarkVarDeclODRUsed failed to cleanup MaybeODRUseExprs?");
 }
 
+static void DoMarkPotentialCapture(Sema &SemaRef, SourceLocation Loc,
+                                   ValueDecl *Var, Expr *E) {
+  VarDecl *VD = Var->getPotentiallyDecomposedVarDecl();
+  if (!VD)
+    return;
+
+  const bool RefersToEnclosingScope =
+      (SemaRef.CurContext != VD->getDeclContext() &&
+       VD->getDeclContext()->isFunctionOrMethod() && VD->hasLocalStorage());
+  if (RefersToEnclosingScope) {
+    LambdaScopeInfo *const LSI =
+        SemaRef.getCurLambda(/*IgnoreNonLambdaCapturingScope=*/true);
+    if (LSI && (!LSI->CallOperator ||
+                !LSI->CallOperator->Encloses(Var->getDeclContext()))) {
+      // If a variable could potentially be odr-used, defer marking it so
+      // until we finish analyzing the full expression for any
+      // lvalue-to-rvalue
+      // or discarded value conversions that would obviate odr-use.
+      // Add it to the list of potential captures that will be analyzed
+      // later (ActOnFinishFullExpr) for eventual capture and odr-use marking
+      // unless the variable is a reference that was initialized by a constant
+      // expression (this will never need to be captured or odr-used).
+      //
+      // FIXME: We can simplify this a lot after implementing P0588R1.
+      assert(E && "Capture variable should be used in an expression.");
+      if (!Var->getType()->isReferenceType() ||
+          !VD->isUsableInConstantExpressions(SemaRef.Context))
+        LSI->addPotentialCapture(E->IgnoreParens());
+    }
+  }
+}
+
 static void DoMarkVarDeclReferenced(
     Sema &SemaRef, SourceLocation Loc, VarDecl *Var, Expr *E,
     llvm::DenseMap<const VarDecl *, int> &RefsMinusAssignments) {
@@ -19877,36 +19906,13 @@
     // odr-used, but we may still need to track them for lambda capture.
     // FIXME: Do we also need to do this inside dependent typeid expressions
     // (which are modeled as unevaluated at this point)?
-    const bool RefersToEnclosingScope =
-        (SemaRef.CurContext != Var->getDeclContext() &&
-         Var->getDeclContext()->isFunctionOrMethod() && Var->hasLocalStorage());
-    if (RefersToEnclosingScope) {
-      LambdaScopeInfo *const LSI =
-          SemaRef.getCurLambda(/*IgnoreNonLambdaCapturingScope=*/true);
-      if (LSI && (!LSI->CallOperator ||
-                  !LSI->CallOperator->Encloses(Var->getDeclContext()))) {
-        // If a variable could potentially be odr-used, defer marking it so
-        // until we finish analyzing the full expression for any
-        // lvalue-to-rvalue
-        // or discarded value conversions that would obviate odr-use.
-        // Add it to the list of potential captures that will be analyzed
-        // later (ActOnFinishFullExpr) for eventual capture and odr-use marking
-        // unless the variable is a reference that was initialized by a constant
-        // expression (this will never need to be captured or odr-used).
-        //
-        // FIXME: We can simplify this a lot after implementing P0588R1.
-        assert(E && "Capture variable should be used in an expression.");
-        if (!Var->getType()->isReferenceType() ||
-            !Var->isUsableInConstantExpressions(SemaRef.Context))
-          LSI->addPotentialCapture(E->IgnoreParens());
-      }
-    }
+    DoMarkPotentialCapture(SemaRef, Loc, Var, E);
     break;
   }
 }
 
 static void DoMarkBindingDeclReferenced(Sema &SemaRef, SourceLocation Loc,
-                                        BindingDecl *BD) {
+                                        BindingDecl *BD, Expr *E) {
   BD->setReferenced();
 
   if (BD->isInvalidDecl())
@@ -19920,6 +19926,8 @@
                                /*BuildAndDiagnose*/ true, CaptureType,
                                DeclRefType,
                                /*FunctionScopeIndexToStopAt*/ nullptr);
+  } else if (OdrUse == OdrUseContext::Dependent) {
+    DoMarkPotentialCapture(SemaRef, Loc, BD, E);
   }
 }
 
@@ -19943,7 +19951,7 @@
   }
 
   if (BindingDecl *Decl = dyn_cast<BindingDecl>(D)) {
-    DoMarkBindingDeclReferenced(SemaRef, Loc, Decl);
+    DoMarkBindingDeclReferenced(SemaRef, Loc, Decl, E);
     return;
   }
 
diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp
--- a/clang/lib/Sema/SemaExprCXX.cpp
+++ b/clang/lib/Sema/SemaExprCXX.cpp
@@ -8283,7 +8283,7 @@
   // All the potentially captureable variables in the current nested
   // lambda (within a generic outer lambda), must be captured by an
   // outer lambda that is enclosed within a non-dependent context.
-  CurrentLSI->visitPotentialCaptures([&] (VarDecl *Var, Expr *VarExpr) {
+  CurrentLSI->visitPotentialCaptures([&](ValueDecl *Var, Expr *VarExpr) {
     // If the variable is clearly identified as non-odr-used and the full
     // expression is not instantiation dependent, only then do we not
     // need to check enclosing lambda's for speculative captures.
@@ -8299,6 +8299,10 @@
         !IsFullExprInstantiationDependent)
       return;
 
+    VarDecl *UnderlyingVar = Var->getPotentiallyDecomposedVarDecl();
+    if (!UnderlyingVar)
+      return;
+
     // If we have a capture-capable lambda for the variable, go ahead and
     // capture the variable in that lambda (and all its enclosing lambdas).
     if (const Optional<unsigned> Index =
@@ -8306,7 +8310,7 @@
                 S.FunctionScopes, Var, S))
       S.MarkCaptureUsedInEnclosingContext(Var, VarExpr->getExprLoc(), *Index);
     const bool IsVarNeverAConstantExpression =
-        VariableCanNeverBeAConstantExpression(Var, S.Context);
+        VariableCanNeverBeAConstantExpression(UnderlyingVar, S.Context);
     if (!IsFullExprInstantiationDependent || IsVarNeverAConstantExpression) {
       // This full expression is not instantiation dependent or the variable
       // can not be used in a constant expression - which means
diff --git a/clang/lib/Sema/SemaLambda.cpp b/clang/lib/Sema/SemaLambda.cpp
--- a/clang/lib/Sema/SemaLambda.cpp
+++ b/clang/lib/Sema/SemaLambda.cpp
@@ -62,7 +62,7 @@
 static inline Optional<unsigned>
 getStackIndexOfNearestEnclosingCaptureReadyLambda(
     ArrayRef<const clang::sema::FunctionScopeInfo *> FunctionScopes,
-    VarDecl *VarToCapture) {
+    ValueDecl *VarToCapture) {
   // Label failure to capture.
   const Optional<unsigned> NoLambdaIsCaptureReady;
 
@@ -172,7 +172,7 @@
 
 Optional<unsigned> clang::getStackIndexOfNearestEnclosingCaptureCapableLambda(
     ArrayRef<const sema::FunctionScopeInfo *> FunctionScopes,
-    VarDecl *VarToCapture, Sema &S) {
+    ValueDecl *VarToCapture, Sema &S) {
 
   const Optional<unsigned> NoLambdaIsCaptureCapable;
 
@@ -1232,11 +1232,7 @@
     if (Var->isInvalidDecl())
       continue;
 
-    VarDecl *Underlying;
-    if (auto *BD = dyn_cast<BindingDecl>(Var))
-      Underlying = dyn_cast<VarDecl>(BD->getDecomposedDecl());
-    else
-      Underlying = cast<VarDecl>(Var);
+    VarDecl *Underlying = Var->getPotentiallyDecomposedVarDecl();
 
     if (!Underlying->hasLocalStorage()) {
       Diag(C->Loc, diag::err_capture_non_automatic_variable) << C->Id;
diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
--- a/clang/lib/Sema/TreeTransform.h
+++ b/clang/lib/Sema/TreeTransform.h
@@ -13399,9 +13399,8 @@
     }
 
     // Transform the captured variable.
-    VarDecl *CapturedVar
-      = cast_or_null<VarDecl>(getDerived().TransformDecl(C->getLocation(),
-                                                         C->getCapturedVar()));
+    auto *CapturedVar = cast_or_null<ValueDecl>(
+        getDerived().TransformDecl(C->getLocation(), C->getCapturedVar()));
     if (!CapturedVar || CapturedVar->isInvalidDecl()) {
       Invalid = true;
       continue;
diff --git a/clang/test/SemaCXX/cxx20-decomposition.cpp b/clang/test/SemaCXX/cxx20-decomposition.cpp
--- a/clang/test/SemaCXX/cxx20-decomposition.cpp
+++ b/clang/test/SemaCXX/cxx20-decomposition.cpp
@@ -1,5 +1,4 @@
-// RUN: %clang_cc1 -fsyntax-only -std=c++20 -verify %s
-// expected-no-diagnostics
+// RUN: %clang_cc1 -fsyntax-only -std=c++20 -verify -Wunused-variable %s
 
 template <typename, typename>
 constexpr bool is_same = false;
@@ -80,7 +79,17 @@
 namespace std {
 
 template <typename T>
-struct tuple_size {
+struct tuple_size;
+
+template <typename T>
+struct tuple_size<T&> : tuple_size<T>{};
+
+template <typename T>
+requires requires { tuple_size<T>::value; }
+struct tuple_size<const T> : tuple_size<T>{};
+
+template <>
+struct tuple_size<tuple> {
   static constexpr unsigned long value = 2;
 };
 
@@ -139,3 +148,37 @@
     };
   }
 }
+
+namespace ODRUseTests {
+  struct P { int a; int b; };
+  void GH57826() {
+    const auto [a, b] = P{1, 2}; //expected-note 2{{'b' declared here}} \
+                                 //expected-note 3{{'a' declared here}}
+    (void)[&](auto c) { return b + [&a] {
+        return a;
+    }(); }(0);
+    (void)[&](auto c) { return b + [&a](auto) {
+        return a;
+    }(0); }(0);
+    (void)[=](auto c) { return b + [&a](auto) {
+        return a;
+    }(0); }(0);
+    (void)[&a,&b](auto c) { return b + [&a](auto) {
+        return a;
+    }(0); }(0);
+    (void)[&a,&b](auto c) { return b + [a](auto) {
+        return a;
+    }(0); }(0);
+    (void)[&a](auto c) { return b + [&a](auto) { // expected-error 2{{variable 'b' cannot be implicitly captured}} \
+                                                 // expected-note 2{{lambda expression begins here}} \
+                                                 // expected-note 4{{capture 'b'}}
+        return a;
+    }(0); }(0); // expected-note {{in instantiation}}
+    (void)[&b](auto c) { return b + [](auto) {   // expected-note 3{{lambda expression begins here}} \
+                                                 // expected-note 6{{capture 'a'}} \
+                                                 // expected-note 6{{default capture}} \
+                                                 // expected-note {{in instantiation}}
+        return a;  // expected-error 3{{variable 'a' cannot be implicitly captured}}
+    }(0); }(0); // expected-note 2{{in instantiation}}
+  }
+}