For DR712: store on a DeclRefExpr whether it constitutes an odr-use.

Begin restructuring to support the forms of non-odr-use reference
permitted by DR712.

llvm-svn: 363086

1 files changed, 17 insertions, 2 deletions

diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index 6c5847ddfcd..d0ff0994ed8 100644
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -285,7 +285,7 @@ static void instantiateOMPDeclareSimdDeclAttr(
   SmallVector<Expr *, 4> Uniforms, Aligneds, Alignments, Linears, Steps;
   SmallVector<unsigned, 4> LinModifiers;
 
-  auto &&Subst = [&](Expr *E) -> ExprResult {
+  auto SubstExpr = [&](Expr *E) -> ExprResult {
     if (auto *DRE = dyn_cast<DeclRefExpr>(E->IgnoreParenImpCasts()))
       if (auto *PVD = dyn_cast<ParmVarDecl>(DRE->getDecl())) {
         Sema::ContextRAII SavedContext(S, FD);
@@ -300,6 +300,17 @@ static void instantiateOMPDeclareSimdDeclAttr(
     return S.SubstExpr(E, TemplateArgs);
   };
 
+  // Substitute a single OpenMP clause, which is a potentially-evaluated
+  // full-expression.
+  auto Subst = [&](Expr *E) -> ExprResult {
+    EnterExpressionEvaluationContext Evaluated(
+        S, Sema::ExpressionEvaluationContext::PotentiallyEvaluated);
+    ExprResult Res = SubstExpr(E);
+    if (Res.isInvalid())
+      return Res;
+    return S.ActOnFinishFullExpr(Res.get(), false);
+  };
+
   ExprResult Simdlen;
   if (auto *E = Attr.getSimdlen())
     Simdlen = Subst(E);
@@ -4714,8 +4725,12 @@ void Sema::InstantiateVariableDefinition(SourceLocation PointOfInstantiation,
   //   of reference types, [...] explicit instantiation declarations
   //   have the effect of suppressing the implicit instantiation of the entity
   //   to which they refer.
+  //
+  // FIXME: That's not exactly the same as "might be usable in constant
+  // expressions", which only allows constexpr variables and const integral
+  // types, not arbitrary const literal types.
   if (TSK == TSK_ExplicitInstantiationDeclaration &&
-      !Var->isUsableInConstantExpressions(getASTContext()))
+      !Var->mightBeUsableInConstantExpressions(getASTContext()))
     return;
 
   // Make sure to pass the instantiated variable to the consumer at the end.