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
@@ -1297,6 +1297,11 @@
       EK_Decltype, EK_TemplateArgument, EK_Other
     } ExprContext;
 
+    // A context can be nested in both a discarded statement context and
+    // an immediate function context, so they need to be tracked independently.
+    bool InDiscardedStatement;
+    bool InImmediateFunctionContext;
+
     ExpressionEvaluationContextRecord(ExpressionEvaluationContext Context,
                                       unsigned NumCleanupObjects,
                                       CleanupInfo ParentCleanup,
@@ -1304,7 +1309,8 @@
                                       ExpressionKind ExprContext)
         : Context(Context), ParentCleanup(ParentCleanup),
           NumCleanupObjects(NumCleanupObjects), NumTypos(0),
-          ManglingContextDecl(ManglingContextDecl), ExprContext(ExprContext) {}
+          ManglingContextDecl(ManglingContextDecl), ExprContext(ExprContext),
+          InDiscardedStatement(false), InImmediateFunctionContext(false) {}
 
     bool isUnevaluated() const {
       return Context == ExpressionEvaluationContext::Unevaluated ||
@@ -1318,7 +1324,13 @@
     }
 
     bool isImmediateFunctionContext() const {
-      return Context == ExpressionEvaluationContext::ImmediateFunctionContext;
+      return Context == ExpressionEvaluationContext::ImmediateFunctionContext ||
+             InImmediateFunctionContext;
+    }
+
+    bool isDiscardedStatementContext() const {
+      return Context == ExpressionEvaluationContext::DiscardedStatement ||
+             InDiscardedStatement;
     }
   };
 
@@ -9140,14 +9152,7 @@
   bool isImmediateFunctionContext() const {
     assert(!ExprEvalContexts.empty() &&
            "Must be in an expression evaluation context");
-    for (const ExpressionEvaluationContextRecord &context :
-         llvm::reverse(ExprEvalContexts)) {
-      if (context.isImmediateFunctionContext())
-        return true;
-      if (context.isUnevaluated())
-        return false;
-    }
-    return false;
+    return ExprEvalContexts.back().isImmediateFunctionContext();
   }
 
   /// RAII class used to determine whether SFINAE has
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
@@ -16567,6 +16567,17 @@
     ExpressionEvaluationContextRecord::ExpressionKind ExprContext) {
   ExprEvalContexts.emplace_back(NewContext, ExprCleanupObjects.size(), Cleanup,
                                 LambdaContextDecl, ExprContext);
+
+  // Discarded statements and immediate contexts nested in other
+  // discarded statements or immediate context are themselves
+  // a discarded statement or an immediate context, respectively.
+  ExprEvalContexts.back().InDiscardedStatement =
+      ExprEvalContexts[ExprEvalContexts.size() - 2]
+          .isDiscardedStatementContext();
+  ExprEvalContexts.back().InImmediateFunctionContext =
+      ExprEvalContexts[ExprEvalContexts.size() - 2]
+          .isImmediateFunctionContext();
+
   Cleanup.reset();
   if (!MaybeODRUseExprs.empty())
     std::swap(MaybeODRUseExprs, ExprEvalContexts.back().SavedMaybeODRUseExprs);
@@ -18956,6 +18967,10 @@
 /// during overload resolution or within sizeof/alignof/typeof/typeid.
 bool Sema::DiagRuntimeBehavior(SourceLocation Loc, ArrayRef<const Stmt*> Stmts,
                                const PartialDiagnostic &PD) {
+
+  if (ExprEvalContexts.back().isDiscardedStatementContext())
+    return false;
+
   switch (ExprEvalContexts.back().Context) {
   case ExpressionEvaluationContext::Unevaluated:
   case ExpressionEvaluationContext::UnevaluatedList:
diff --git a/clang/lib/Sema/SemaStmt.cpp b/clang/lib/Sema/SemaStmt.cpp
--- a/clang/lib/Sema/SemaStmt.cpp
+++ b/clang/lib/Sema/SemaStmt.cpp
@@ -3563,8 +3563,7 @@
   bool HasDeducedReturnType =
       CurLambda && hasDeducedReturnType(CurLambda->CallOperator);
 
-  if (ExprEvalContexts.back().Context ==
-          ExpressionEvaluationContext::DiscardedStatement &&
+  if (ExprEvalContexts.back().isDiscardedStatementContext() &&
       (HasDeducedReturnType || CurCap->HasImplicitReturnType)) {
     if (RetValExp) {
       ExprResult ER =
@@ -3880,8 +3879,7 @@
   if (RetVal.isInvalid())
     return StmtError();
   StmtResult R = BuildReturnStmt(ReturnLoc, RetVal.get());
-  if (R.isInvalid() || ExprEvalContexts.back().Context ==
-                           ExpressionEvaluationContext::DiscardedStatement)
+  if (R.isInvalid() || ExprEvalContexts.back().isDiscardedStatementContext())
     return R;
 
   if (VarDecl *VD =
@@ -3966,8 +3964,7 @@
 
   // C++1z: discarded return statements are not considered when deducing a
   // return type.
-  if (ExprEvalContexts.back().Context ==
-          ExpressionEvaluationContext::DiscardedStatement &&
+  if (ExprEvalContexts.back().isDiscardedStatementContext() &&
       FnRetType->getContainedAutoType()) {
     if (RetValExp) {
       ExprResult ER =
diff --git a/clang/test/SemaCXX/cxx2b-consteval-if.cpp b/clang/test/SemaCXX/cxx2b-consteval-if.cpp
--- a/clang/test/SemaCXX/cxx2b-consteval-if.cpp
+++ b/clang/test/SemaCXX/cxx2b-consteval-if.cpp
@@ -52,6 +52,5 @@
       return 0;
     }
   }
-  // FIXME: this error should not happen.
-  return 0.0; // expected-error {{'auto' in return type deduced as 'double' here but deduced as 'int' in earlier return statement}}
+  return 0.0;
 }