P0859R0: List-initialization is potentially-constant-evaluated and

triggers instantiation of constexpr functions.

We mostly implemented this since Clang 6, but missed the template
instantiation case.

We do not implement the '&cast-expression' special case. It appears to
be a mistake / oversight. I've mailed CWG to see if we can remove it.

llvm-svn: 343064

1 files changed, 32 insertions, 9 deletions

diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
index 2bee5e7ec82..3ec467a39ca 100644
--- a/clang/lib/Sema/TreeTransform.h
+++ b/clang/lib/Sema/TreeTransform.h
@@ -3386,6 +3386,11 @@ ExprResult TreeTransform<Derived>::TransformInitializer(Expr *Init,
   if (Construct && Construct->isStdInitListInitialization())
     return TransformInitializer(Construct->getArg(0), NotCopyInit);
 
+  // Enter a list-init context if this was list initialization.
+  EnterExpressionEvaluationContext Context(
+      getSema(), EnterExpressionEvaluationContext::InitList,
+      Construct->isListInitialization());
+
   SmallVector<Expr*, 8> NewArgs;
   bool ArgChanged = false;
   if (getDerived().TransformExprs(Construct->getArgs(), Construct->getNumArgs(),
@@ -9549,6 +9554,9 @@ TreeTransform<Derived>::TransformInitListExpr(InitListExpr *E) {
 
   bool InitChanged = false;
 
+  EnterExpressionEvaluationContext Context(
+      getSema(), EnterExpressionEvaluationContext::InitList);
+
   SmallVector<Expr*, 4> Inits;
   if (getDerived().TransformExprs(E->getInits(), E->getNumInits(), false,
                                   Inits, &InitChanged))
@@ -10780,9 +10788,14 @@ TreeTransform<Derived>::TransformCXXConstructExpr(CXXConstructExpr *E) {
 
   bool ArgumentChanged = false;
   SmallVector<Expr*, 8> Args;
-  if (getDerived().TransformExprs(E->getArgs(), E->getNumArgs(), true, Args,
-                                  &ArgumentChanged))
-    return ExprError();
+  {
+    EnterExpressionEvaluationContext Context(
+        getSema(), EnterExpressionEvaluationContext::InitList,
+        E->isListInitialization());
+    if (getDerived().TransformExprs(E->getArgs(), E->getNumArgs(), true, Args,
+                                    &ArgumentChanged))
+      return ExprError();
+  }
 
   if (!getDerived().AlwaysRebuild() &&
       T == E->getType() &&
@@ -10865,9 +10878,14 @@ TreeTransform<Derived>::TransformCXXTemporaryObjectExpr(
   bool ArgumentChanged = false;
   SmallVector<Expr*, 8> Args;
   Args.reserve(E->getNumArgs());
-  if (TransformExprs(E->getArgs(), E->getNumArgs(), true, Args,
-                     &ArgumentChanged))
-    return ExprError();
+  {
+    EnterExpressionEvaluationContext Context(
+        getSema(), EnterExpressionEvaluationContext::InitList,
+        E->isListInitialization());
+    if (TransformExprs(E->getArgs(), E->getNumArgs(), true, Args,
+                       &ArgumentChanged))
+      return ExprError();
+  }
 
   if (!getDerived().AlwaysRebuild() &&
       T == E->getTypeSourceInfo() &&
@@ -11159,9 +11177,14 @@ TreeTransform<Derived>::TransformCXXUnresolvedConstructExpr(
   bool ArgumentChanged = false;
   SmallVector<Expr*, 8> Args;
   Args.reserve(E->arg_size());
-  if (getDerived().TransformExprs(E->arg_begin(), E->arg_size(), true, Args,
-                                  &ArgumentChanged))
-    return ExprError();
+  {
+    EnterExpressionEvaluationContext Context(
+        getSema(), EnterExpressionEvaluationContext::InitList,
+        E->isListInitialization());
+    if (getDerived().TransformExprs(E->arg_begin(), E->arg_size(), true, Args,
+                                    &ArgumentChanged))
+      return ExprError();
+  }
 
   if (!getDerived().AlwaysRebuild() &&
       T == E->getTypeSourceInfo() &&