Index: clang-tools-extra/clang-tidy/misc/RedundantExpressionCheck.cpp
===================================================================
--- clang-tools-extra/clang-tidy/misc/RedundantExpressionCheck.cpp
+++ clang-tools-extra/clang-tidy/misc/RedundantExpressionCheck.cpp
@@ -51,10 +51,27 @@
 
 static bool areEquivalentNameSpecifier(const NestedNameSpecifier *Left,
                                        const NestedNameSpecifier *Right) {
-  llvm::FoldingSetNodeID LeftID, RightID;
-  Left->Profile(LeftID);
-  Right->Profile(RightID);
-  return LeftID == RightID;
+  if (const auto *L = Left->getAsType())
+    if (const auto *R = Right->getAsType())
+      return L->getCanonicalTypeUnqualified() ==
+             R->getCanonicalTypeUnqualified();
+
+  // FIXME: We should probably check the other kinds of nested name specifiers.
+  return true;
+}
+
+static bool areEquivalentDeclRefs(const DeclRefExpr *Left,
+                                  const DeclRefExpr *Right) {
+  if (Left->getDecl()->getCanonicalDecl() !=
+      Right->getDecl()->getCanonicalDecl()) {
+    return false;
+  }
+
+  // The decls were already matched, so just return true at any later point.
+  if (!Left->hasQualifier() || !Right->hasQualifier())
+    return true;
+  return areEquivalentNameSpecifier(Left->getQualifier(),
+                                    Right->getQualifier());
 }
 
 static bool areEquivalentExpr(const Expr *Left, const Expr *Right) {
@@ -111,9 +128,11 @@
     return areEquivalentNameSpecifier(
         cast<DependentScopeDeclRefExpr>(Left)->getQualifier(),
         cast<DependentScopeDeclRefExpr>(Right)->getQualifier());
-  case Stmt::DeclRefExprClass:
-    return cast<DeclRefExpr>(Left)->getDecl() ==
-           cast<DeclRefExpr>(Right)->getDecl();
+  case Stmt::DeclRefExprClass: {
+    const DeclRefExpr *DeclRef1 = cast<DeclRefExpr>(Left);
+    const DeclRefExpr *DeclRef2 = cast<DeclRefExpr>(Right);
+    return areEquivalentDeclRefs(DeclRef1, DeclRef2);
+  }
   case Stmt::MemberExprClass:
     return cast<MemberExpr>(Left)->getMemberDecl() ==
            cast<MemberExpr>(Right)->getMemberDecl();
Index: clang-tools-extra/test/clang-tidy/checkers/misc-redundant-expression.cpp
===================================================================
--- clang-tools-extra/test/clang-tidy/checkers/misc-redundant-expression.cpp
+++ clang-tools-extra/test/clang-tidy/checkers/misc-redundant-expression.cpp
@@ -807,3 +807,52 @@
 };
 
 } // namespace no_crash
+
+template <bool V> struct boolean_value {
+  static constexpr bool value = V;
+};
+template <typename T> struct my_trait : boolean_value<true> {};
+
+bool respect_nested_name_specifiers(bool sink) {
+  sink |= my_trait<char>::value || my_trait<int>::value; // no-warning
+
+  sink |= my_trait<char>::value || my_trait<char>::value;
+  // CHECK-MESSAGES: :[[@LINE-1]]:33: warning: both sides of operator are equivalent
+
+  using my_char = char;
+  sink |= my_trait<char>::value || my_trait<my_char>::value;
+  // CHECK-MESSAGES: :[[@LINE-1]]:33: warning: both sides of operator are equivalent
+
+  return sink;
+}
+
+static void static_function() {}
+namespace my {
+int fn(int = 1);
+}
+void respect_namespaces(bool coin) {
+  namespace other = my;
+  using namespace other;
+
+  coin ? my::fn(1) : my::fn(2);    // no-warning
+  coin ? my::fn(1) : other::fn(2); // no-warning
+
+  // CHECK-MESSAGES: :[[@LINE+3]]:20: warning: 'true' and 'false' expressions are equivalent
+  // CHECK-MESSAGES: :[[@LINE+3]]:20: warning: 'true' and 'false' expressions are equivalent
+  // CHECK-MESSAGES: :[[@LINE+3]]:20: warning: 'true' and 'false' expressions are equivalent
+  coin ? my::fn(1) : my::fn(1);
+  coin ? my::fn(1) : other::fn(1);
+  coin ? my::fn(1) : fn(1);
+
+  coin ? my::fn(1) : fn(); // FIXME: We should have a warning for this: the default parameter is also 1.
+
+  // CHECK-MESSAGES: :[[@LINE+2]]:13: warning: both sides of operator are equivalent [misc-redundant-expression]
+  // CHECK-MESSAGES: :[[@LINE+2]]:13: warning: both sides of operator are equivalent [misc-redundant-expression]
+  my::fn(1) & my::fn(1);
+  my::fn(1) & other::fn(1);
+
+  // CHECK-MESSAGES: :[[@LINE+2]]:30: warning: 'true' and 'false' expressions are equivalent
+  // CHECK-MESSAGES: :[[@LINE+2]]:30: warning: 'true' and 'false' expressions are equivalent
+  coin ? ::static_function() : ::static_function();
+  coin ? ::static_function() : static_function();
+}
Index: clang/lib/StaticAnalyzer/Checkers/IdenticalExprChecker.cpp
===================================================================
--- clang/lib/StaticAnalyzer/Checkers/IdenticalExprChecker.cpp
+++ clang/lib/StaticAnalyzer/Checkers/IdenticalExprChecker.cpp
@@ -295,6 +295,31 @@
   return true;
 }
 
+static bool areEquivalentNameSpecifier(const NestedNameSpecifier *Left,
+                                       const NestedNameSpecifier *Right) {
+  if (const auto *L = Left->getAsType())
+    if (const auto *R = Right->getAsType())
+      return L->getCanonicalTypeUnqualified() ==
+             R->getCanonicalTypeUnqualified();
+
+  // FIXME: We should probably check the other kinds of nested name specifiers.
+  return true;
+}
+
+static bool areEquivalentDeclRefs(const DeclRefExpr *Left,
+                                  const DeclRefExpr *Right) {
+  if (Left->getDecl()->getCanonicalDecl() !=
+      Right->getDecl()->getCanonicalDecl()) {
+    return false;
+  }
+
+  // The decls were already matched, so just return true at any later point.
+  if (!Left->hasQualifier() || !Right->hasQualifier())
+    return true;
+  return areEquivalentNameSpecifier(Left->getQualifier(),
+                                    Right->getQualifier());
+}
+
 /// Determines whether two statement trees are identical regarding
 /// operators and symbols.
 ///
@@ -461,7 +486,7 @@
   case Stmt::DeclRefExprClass: {
     const DeclRefExpr *DeclRef1 = cast<DeclRefExpr>(Stmt1);
     const DeclRefExpr *DeclRef2 = cast<DeclRefExpr>(Stmt2);
-    return DeclRef1->getDecl() == DeclRef2->getDecl();
+    return areEquivalentDeclRefs(DeclRef1, DeclRef2);
   }
   case Stmt::IntegerLiteralClass: {
     const IntegerLiteral *IntLit1 = cast<IntegerLiteral>(Stmt1);
Index: clang/test/Analysis/identical-expressions.cpp
===================================================================
--- clang/test/Analysis/identical-expressions.cpp
+++ clang/test/Analysis/identical-expressions.cpp
@@ -1562,3 +1562,50 @@
       ;
   }
 }
+
+template <bool V> struct boolean_value {
+  static constexpr bool value = V;
+};
+template <typename T> struct my_trait : boolean_value<true> {};
+
+bool respect_nested_name_specifiers(bool sink) {
+  sink |= my_trait<char>::value || my_trait<int>::value; // no-warning
+
+  sink |= my_trait<char>::value || my_trait<char>::value;
+  // expected-warning@-1 {{identical expressions on both sides of logical operator}}
+
+  using my_char = char;
+  sink |= my_trait<char>::value || my_trait<my_char>::value;
+  // expected-warning@-1 {{identical expressions on both sides of logical operator}}
+
+  return sink;
+}
+
+static void static_function() {}
+namespace my {
+int fn(int = 1);
+}
+void respect_namespaces(bool coin) {
+  namespace other = my;
+  using namespace other;
+
+  coin ? my::fn(1) : my::fn(2);    // no-warning
+  coin ? my::fn(1) : other::fn(2); // no-warning
+
+  // expected-warning@+3 {{identical expressions on both sides of ':' in conditional expression}}
+  // expected-warning@+3 {{identical expressions on both sides of ':' in conditional expression}}
+  // expected-warning@+3 {{identical expressions on both sides of ':' in conditional expression}}
+  coin ? my::fn(1) : my::fn(1);
+  coin ? my::fn(1) : other::fn(1);
+  coin ? my::fn(1) : fn(1);
+
+  coin ? my::fn(1) : fn(); // FIXME: We should have a warning for this: the default parameter is also 1.
+
+  my::fn(1) & my::fn(1);    // no-warning
+  my::fn(1) & other::fn(1); // no-warning
+
+  // expected-warning@+2 {{identical expressions on both sides of ':' in conditional expression}}
+  // expected-warning@+2 {{identical expressions on both sides of ':' in conditional expression}}
+  coin ? ::static_function() : ::static_function();
+  coin ? ::static_function() : static_function();
+}