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
@@ -5917,8 +5917,15 @@
     assert(!InitWithCleanup->getNumObjects() &&
            "default argument expression has capturing blocks?");
   }
+  // C++ [expr.const]p15.1:
+  //   An expression or conversion is in an immediate function context if it is
+  //   potentially evaluated and [...] its innermost enclosing non-block scope
+  //   is a function parameter scope of an immediate function.
   EnterExpressionEvaluationContext EvalContext(
-      *this, ExpressionEvaluationContext::PotentiallyEvaluated, Param);
+      *this,
+      FD->isConsteval() ? ExpressionEvaluationContext::ImmediateFunctionContext
+                        : ExpressionEvaluationContext::PotentiallyEvaluated,
+      Param);
   ExprEvalContexts.back().IsCurrentlyCheckingDefaultArgumentOrInitializer =
       SkipImmediateInvocations;
   MarkDeclarationsReferencedInExpr(Init, /*SkipLocalVariables*/ true);
@@ -6005,8 +6012,16 @@
     // Mark that we are replacing a default argument first.
     // If we are instantiating a template we won't have to
     // retransform immediate calls.
+    // C++ [expr.const]p15.1:
+    //   An expression or conversion is in an immediate function context if it
+    //   is potentially evaluated and [...] its innermost enclosing non-block
+    //   scope is a function parameter scope of an immediate function.
     EnterExpressionEvaluationContext EvalContext(
-        *this, ExpressionEvaluationContext::PotentiallyEvaluated, Param);
+        *this,
+        FD->isConsteval()
+            ? ExpressionEvaluationContext::ImmediateFunctionContext
+            : ExpressionEvaluationContext::PotentiallyEvaluated,
+        Param);
 
     if (Param->hasUninstantiatedDefaultArg()) {
       if (InstantiateDefaultArgument(CallLoc, FD, Param))
diff --git a/clang/test/CXX/expr/expr.const/p6-2a.cpp b/clang/test/CXX/expr/expr.const/p6-2a.cpp
--- a/clang/test/CXX/expr/expr.const/p6-2a.cpp
+++ b/clang/test/CXX/expr/expr.const/p6-2a.cpp
@@ -43,14 +43,12 @@
 constexpr Temporary t = {3}; // expected-error {{must have constant destruction}} expected-note {{created here}} expected-note {{in call}}
 
 namespace P1073R3 {
-consteval int f() { return 42; } // expected-note 3 {{declared here}}
+consteval int f() { return 42; } // expected-note 2 {{declared here}}
 consteval auto g() { return f; }
-// FIXME: there should be no diagnostics associated with either h() or r.
-consteval int h(int (*p)() = g()) { return p(); } // expected-error {{call to consteval function 'P1073R3::g' is not a constant expression}} \
-                                                     expected-note {{declared here}} \
-                                                     expected-note {{pointer to a consteval declaration is not a constant expression}}
-constexpr int r = h();   // expected-note {{in the default initalizer of 'p'}}
+consteval int h(int (*p)() = g()) { return p(); }
+constexpr int r = h();
 constexpr auto e = g();  // expected-error {{call to consteval function 'P1073R3::g' is not a constant expression}} \
                             expected-error {{constexpr variable 'e' must be initialized by a constant expression}} \
                             expected-note 2 {{pointer to a consteval declaration is not a constant expression}}
+static_assert(r == 42);
 } // namespace P1073R3