[clang] [clang] Use new interpreter in EvaluateAsConstantExpr if requested (PR #70763)

[Timm Baeder via cfe-commits]

https://github.com/tbaederr updated https://github.com/llvm/llvm-project/pull/70763

>From 95db8094955756851e59a377cc13af9c30987221 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Timm=20B=C3=A4der?= <tbaeder at redhat.com>
Date: Mon, 30 Oct 2023 16:14:24 +0100
Subject: [PATCH] [clang] Use new interpreter in EvaluateAsConstantExpr if
 requested

EvaluateAsConstantExpr() uses ::EvaluateInPlace() directly, which does
not use the new interpreter if requested. Do it here, which is the same
pattern we use in EvaluateAsInitializer.
---
 clang/lib/AST/ExprConstant.cpp     | 16 +++++++++-------
 clang/test/AST/Interp/literals.cpp |  4 +---
 2 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 4aa8045bc93be71..373972eb6cab11b 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -15672,12 +15672,14 @@ bool Expr::EvaluateAsConstantExpr(EvalResult &Result, const ASTContext &Ctx,
   // this doesn't escape.
   MaterializeTemporaryExpr BaseMTE(T, const_cast<Expr*>(this), true);
   APValue::LValueBase Base(&BaseMTE);
-
   Info.setEvaluatingDecl(Base, Result.Val);
-  LValue LVal;
-  LVal.set(Base);
 
-  {
+  if (Info.EnableNewConstInterp) {
+    if (!Info.Ctx.getInterpContext().evaluateAsRValue(Info, this, Result.Val))
+      return false;
+  } else {
+    LValue LVal;
+    LVal.set(Base);
     // C++23 [intro.execution]/p5
     // A full-expression is [...] a constant-expression
     // So we need to make sure temporary objects are destroyed after having
@@ -15686,10 +15688,10 @@ bool Expr::EvaluateAsConstantExpr(EvalResult &Result, const ASTContext &Ctx,
     if (!::EvaluateInPlace(Result.Val, Info, LVal, this) ||
         Result.HasSideEffects || !Scope.destroy())
       return false;
-  }
 
-  if (!Info.discardCleanups())
-    llvm_unreachable("Unhandled cleanup; missing full expression marker?");
+    if (!Info.discardCleanups())
+      llvm_unreachable("Unhandled cleanup; missing full expression marker?");
+  }
 
   if (!CheckConstantExpression(Info, getExprLoc(), getStorageType(Ctx, this),
                                Result.Val, Kind))
diff --git a/clang/test/AST/Interp/literals.cpp b/clang/test/AST/Interp/literals.cpp
index 68833ec2dc48adf..592b5d6243a80aa 100644
--- a/clang/test/AST/Interp/literals.cpp
+++ b/clang/test/AST/Interp/literals.cpp
@@ -261,15 +261,13 @@ namespace SizeOf {
 #if __cplusplus >= 202002L
   /// FIXME: The following code should be accepted.
   consteval int foo(int n) { // ref-error {{consteval function never produces a constant expression}}
-    return sizeof(int[n]); // ref-note 3{{not valid in a constant expression}} \
-                           // expected-note {{not valid in a constant expression}}
+    return sizeof(int[n]); // ref-note 3{{not valid in a constant expression}}
   }
   constinit int var = foo(5); // ref-error {{not a constant expression}} \
                               // ref-note 2{{in call to}} \
                               // ref-error {{does not have a constant initializer}} \
                               // ref-note {{required by 'constinit' specifier}} \
                               // expected-error  {{is not a constant expression}} \
-                              // expected-note {{in call to}} \
                               // expected-error {{does not have a constant initializer}} \
                               // expected-note {{required by 'constinit' specifier}} \