'[Clang] Fix handling of immediate escalation for inherited constructors

Fixes #112677

Author: cor3ntin

clang/docs/ReleaseNotes.rst

@@ -971,6 +971,7 @@ Bug Fixes to C++ Support
 - Fixed canonicalization of pack indexing types - Clang did not always recognized identical pack indexing. (#GH123033)
 - Fixed a nested lambda substitution issue for constraint evaluation. (#GH123441)
 - Fixed various false diagnostics related to the use of immediate functions. (#GH123472)
+- Fix immediate escalation not propagating through inherited constructors.  (#GH112677)
 
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^

clang/lib/AST/Decl.cpp

@@ -3283,6 +3283,13 @@ bool FunctionDecl::isImmediateEscalating() const {
   // consteval specifier,
   if (isDefaulted() && !isConsteval())
     return true;
+
+  if (auto *CD = dyn_cast<CXXConstructorDecl>(this);
+      CD && CD->isInheritingConstructor())
+    return CD->getInheritedConstructor()
+        .getConstructor()
+        ->isImmediateEscalating();
+
   // - a function that results from the instantiation of a templated entity
   // defined with the constexpr specifier.
   TemplatedKind TK = getTemplatedKind();
@@ -3303,6 +3310,12 @@ bool FunctionDecl::isImmediateFunction() const {
   if (isImmediateEscalating() && BodyContainsImmediateEscalatingExpressions())
     return true;
 
+  if (auto *CD = dyn_cast<CXXConstructorDecl>(this);
+      CD && CD->isInheritingConstructor())
+    return CD->getInheritedConstructor()
+        .getConstructor()
+        ->isImmediateFunction();
+
   if (const auto *MD = dyn_cast<CXXMethodDecl>(this);
       MD && MD->isLambdaStaticInvoker())
     return MD->getParent()->getLambdaCallOperator()->isImmediateFunction();

clang/test/SemaCXX/cxx2b-consteval-propagate.cpp

@@ -496,3 +496,24 @@ struct Y {
 template void g<Y>();
 
 }
+
+namespace GH112677 {
+
+class ConstEval {
+ public:
+  consteval ConstEval(int); // expected-note {{declared here}}
+};
+
+struct B {
+    ConstEval val;
+    template <class Anything = int> constexpr
+    B(int arg) : val(arg) {} // expected-note {{undefined constructor 'ConstEval'}}
+};
+struct C : B {
+    using B::B; // expected-note {{in call to 'B<int>(0)'}}
+};
+
+C c(0); // expected-note{{in implicit initialization for inherited constructor of 'C'}}
+// expected-error@-1 {{call to immediate function 'GH112677::C::B' is not a constant expression}}
+
+}