7 files changed, 46 insertions, 3 deletions
diff --git a/clang/lib/AST/ByteCode/Compiler.cpp b/clang/lib/AST/ByteCode/Compiler.cpp
index ea473730..65ad7ca 100644
--- a/clang/lib/AST/ByteCode/Compiler.cpp
+++ b/clang/lib/AST/ByteCode/Compiler.cpp
@@ -6670,6 +6670,11 @@ bool Compiler<Emitter>::visitDeclRef(const ValueDecl *D, const Expr *E) {
   }
   // Function parameters.
   if (const auto *PVD = dyn_cast<ParmVarDecl>(D)) {
+    if (Ctx.getLangOpts().CPlusPlus && !Ctx.getLangOpts().CPlusPlus11 &&
+        !D->getType()->isIntegralOrEnumerationType()) {
+      return this->emitInvalidDeclRef(cast<DeclRefExpr>(E),
+                                      /*InitializerFailed=*/false, E);
+    }
     if (auto It = this->Params.find(PVD); It != this->Params.end()) {
       if (IsReference || !It->second.IsPtr)
         return this->emitGetParam(classifyPrim(E), It->second.Offset, E);
diff --git a/clang/lib/AST/ByteCode/Context.cpp b/clang/lib/AST/ByteCode/Context.cpp
index a629ff9..ead6e4a 100644
--- a/clang/lib/AST/ByteCode/Context.cpp
+++ b/clang/lib/AST/ByteCode/Context.cpp
@@ -52,6 +52,19 @@ bool Context::isPotentialConstantExpr(State &Parent, const FunctionDecl *FD) {
   return Func->isValid();
 }
 
+void Context::isPotentialConstantExprUnevaluated(State &Parent, const Expr *E,
+                                                 const FunctionDecl *FD) {
+  assert(Stk.empty());
+  ++EvalID;
+  size_t StackSizeBefore = Stk.size();
+  Compiler<EvalEmitter> C(*this, *P, Parent, Stk);
+
+  if (!C.interpretCall(FD, E)) {
+    C.cleanup();
+    Stk.clearTo(StackSizeBefore);
+  }
+}
+
 bool Context::evaluateAsRValue(State &Parent, const Expr *E, APValue &Result) {
   ++EvalID;
   bool Recursing = !Stk.empty();
diff --git a/clang/lib/AST/ByteCode/Context.h b/clang/lib/AST/ByteCode/Context.h
index 5898ab5..acf7504 100644
--- a/clang/lib/AST/ByteCode/Context.h
+++ b/clang/lib/AST/ByteCode/Context.h
@@ -47,7 +47,9 @@ public:
   ~Context();
 
   /// Checks if a function is a potential constant expression.
-  bool isPotentialConstantExpr(State &Parent, const FunctionDecl *FnDecl);
+  bool isPotentialConstantExpr(State &Parent, const FunctionDecl *FD);
+  void isPotentialConstantExprUnevaluated(State &Parent, const Expr *E,
+                                          const FunctionDecl *FD);
 
   /// Evaluates a toplevel expression as an rvalue.
   bool evaluateAsRValue(State &Parent, const Expr *E, APValue &Result);
diff --git a/clang/lib/AST/ByteCode/EvalEmitter.cpp b/clang/lib/AST/ByteCode/EvalEmitter.cpp
index 5498065..6e511bc 100644
--- a/clang/lib/AST/ByteCode/EvalEmitter.cpp
+++ b/clang/lib/AST/ByteCode/EvalEmitter.cpp
@@ -90,6 +90,19 @@ EvaluationResult EvalEmitter::interpretAsPointer(const Expr *E,
   return std::move(this->EvalResult);
 }
 
+bool EvalEmitter::interpretCall(const FunctionDecl *FD, const Expr *E) {
+  // Add parameters to the parameter map. The values in the ParamOffset don't
+  // matter in this case as reading from them can't ever work.
+  for (const ParmVarDecl *PD : FD->parameters()) {
+    this->Params.insert({PD, {0, false}});
+  }
+
+  if (!this->visit(E))
+    return false;
+  PrimType T = Ctx.classify(E).value_or(PT_Ptr);
+  return this->emitPop(T, E);
+}
+
 void EvalEmitter::emitLabel(LabelTy Label) { CurrentLabel = Label; }
 
 EvalEmitter::LabelTy EvalEmitter::getLabel() { return NextLabel++; }
diff --git a/clang/lib/AST/ByteCode/EvalEmitter.h b/clang/lib/AST/ByteCode/EvalEmitter.h
index 7303adb..2fe7da6 100644
--- a/clang/lib/AST/ByteCode/EvalEmitter.h
+++ b/clang/lib/AST/ByteCode/EvalEmitter.h
@@ -40,6 +40,9 @@ public:
   EvaluationResult interpretDecl(const VarDecl *VD, bool CheckFullyInitialized);
   /// Interpret the given Expr to a Pointer.
   EvaluationResult interpretAsPointer(const Expr *E, PtrCallback PtrCB);
+  /// Interpret the given expression as if it was in the body of the given
+  /// function, i.e. the parameters of the function are available for use.
+  bool interpretCall(const FunctionDecl *FD, const Expr *E);
 
   /// Clean up all resources.
   void cleanup();
diff --git a/clang/lib/AST/ByteCode/Interp.cpp b/clang/lib/AST/ByteCode/Interp.cpp
index df5e3be..5463aec 100644
--- a/clang/lib/AST/ByteCode/Interp.cpp
+++ b/clang/lib/AST/ByteCode/Interp.cpp
@@ -142,8 +142,12 @@ static bool diagnoseUnknownDecl(InterpState &S, CodePtr OpPC,
     return false;
 
   if (isa<ParmVarDecl>(D)) {
-    if (D->getType()->isReferenceType())
+    if (D->getType()->isReferenceType()) {
+      if (S.inConstantContext() && S.getLangOpts().CPlusPlus &&
+          !S.getLangOpts().CPlusPlus11)
+        diagnoseNonConstVariable(S, OpPC, D);
       return false;
+    }
 
     const SourceInfo &Loc = S.Current->getSource(OpPC);
     if (S.getLangOpts().CPlusPlus11) {
@@ -661,6 +665,9 @@ bool CheckInitialized(InterpState &S, CodePtr OpPC, const Pointer &Ptr,
   if (Ptr.isInitialized())
     return true;
 
+  if (Ptr.isExtern() && S.checkingPotentialConstantExpression())
+    return false;
+
   if (const auto *VD = Ptr.getDeclDesc()->asVarDecl();
       VD && (VD->isConstexpr() || VD->hasGlobalStorage())) {
 
diff --git a/clang/lib/AST/ByteCode/Interp.h b/clang/lib/AST/ByteCode/Interp.h
index ce0ebdd..aac519d 100644
--- a/clang/lib/AST/ByteCode/Interp.h
+++ b/clang/lib/AST/ByteCode/Interp.h
@@ -1308,7 +1308,7 @@ bool Dup(InterpState &S, CodePtr OpPC) {
 
 template <PrimType Name, class T = typename PrimConv<Name>::T>
 bool Pop(InterpState &S, CodePtr OpPC) {
-  S.Stk.pop<T>();
+  S.Stk.discard<T>();
   return true;
 }