From 55763194f1ae90ee9fc7e03dcafc178e5d3ce71e Mon Sep 17 00:00:00 2001
From: peter klausler <pklausler@nvidia.com>
Date: Wed, 12 Sep 2018 13:53:14 -0700
Subject: [PATCH] [flang] Merge with current master, address early review
 comments.

Original-commit: flang-compiler/f18@d1f981ddb431fedcc6aba5e33465ebe85fdf66dc
Reviewed-on: https://github.com/flang-compiler/f18/pull/183
Tree-same-pre-rewrite: false
---
 flang/lib/common/template.h       | 35 ++++--------
 flang/lib/evaluate/expression.cc  |  4 +-
 flang/lib/evaluate/tools.h        |  2 +-
 flang/lib/evaluate/type.h         | 10 ++--
 flang/lib/semantics/expression.cc | 90 ++++++++++++-------------------
 5 files changed, 49 insertions(+), 92 deletions(-)

diff --git a/flang/lib/common/template.h b/flang/lib/common/template.h
index 28f5e6da9bc2..572c0b58b6ef 100644
--- a/flang/lib/common/template.h
+++ b/flang/lib/common/template.h
@@ -78,8 +78,9 @@ struct OverMembersHelper<T, std::tuple<Ts...>> {
   using type = T<Ts...>;
 };
 
-template<template<typename...> class T, typename TorV>
-using OverMembers = typename OverMembersHelper<T, std::decay_t<TorV>>::type;
+template<template<typename...> class T, typename TUPLEorVARIANT>
+using OverMembers =
+    typename OverMembersHelper<T, std::decay_t<TUPLEorVARIANT>>::type;
 
 // SearchMembers<PREDICATE> scans the types that constitute the alternatives
 // of a std::variant instantiation or elements of a std::tuple.
@@ -92,31 +93,14 @@ template<template<typename> class PREDICATE> struct SearchMembersHelper {
   };
 };
 
-template<template<typename> class PREDICATE, typename TorV>
+template<template<typename> class PREDICATE, typename TUPLEorVARIANT>
 constexpr int SearchMembers{
     OverMembers<SearchMembersHelper<PREDICATE>::template Scanner,
-        TorV>::value()};
+        TUPLEorVARIANT>::value()};
 
-template<typename A, typename TorV>
+template<typename A, typename TUPLEorVARIANT>
 constexpr bool HasMember{
-    SearchMembers<MatchType<A>::template Match, TorV> >= 0};
-
-// const A * -> std::optional<A>
-template<typename A> std::optional<A> GetIfNonNull(const A *p) {
-  if (p) {
-    return {*p};
-  }
-  return std::nullopt;
-}
-
-// const std::variant<..., A, ...> -> std::optional<A>
-// i.e., when a variant holds a value of a particular type, return a copy
-// of that value in a std::optional<>.  The type A must be a valid
-// alternative for the variant.
-template<typename A, typename VARIANT>
-std::optional<A> GetIf(const VARIANT &u) {
-  return GetIfNonNull(std::get_if<A>(&u));
-}
+    SearchMembers<MatchType<A>::template Match, TUPLEorVARIANT> >= 0};
 
 // std::optional<std::optional<A>> -> std::optional<A>
 template<typename A>
@@ -209,9 +193,10 @@ template<template<typename> class F, template<typename...> class PACKAGE,
 struct MapTemplateHelper<F, PACKAGE, std::variant<Ts...>> {
   using type = PACKAGE<F<Ts>...>;
 };
-template<template<typename> class F, typename TorV,
+template<template<typename> class F, typename TUPLEorVARIANT,
     template<typename...> class PACKAGE = std::variant>
-using MapTemplate = typename MapTemplateHelper<F, PACKAGE, TorV>::type;
+using MapTemplate =
+    typename MapTemplateHelper<F, PACKAGE, TUPLEorVARIANT>::type;
 
 // std::tuple<std::optional<>...> -> std::optional<std::tuple<...>>
 // i.e., inverts a tuple of optional values into an optional tuple that has
diff --git a/flang/lib/evaluate/expression.cc b/flang/lib/evaluate/expression.cc
index 977e7494e680..1f2decab8f87 100644
--- a/flang/lib/evaluate/expression.cc
+++ b/flang/lib/evaluate/expression.cc
@@ -503,13 +503,13 @@ template<typename RESULT>
 auto ExpressionBase<RESULT>::ScalarValue() const
     -> std::optional<Scalar<Result>> {
   if constexpr (Result::isSpecificType) {
-    if (auto c{common::GetIf<Constant<Result>>(derived().u)}) {
+    if (auto *c{std::get_if<Constant<Result>>(&derived().u)}) {
       return {c->value};
     }
     // TODO: every specifically-typed Expr should support Parentheses
     if constexpr (common::HasMember<Parentheses<Result>,
                       decltype(derived().u)>) {
-      if (auto p{common::GetIf<Parentheses<Result>>(derived().u)}) {
+      if (auto *p{std::get_if<Parentheses<Result>>(&derived().u)}) {
         return p->left().ScalarValue();
       }
     }
diff --git a/flang/lib/evaluate/tools.h b/flang/lib/evaluate/tools.h
index 29186e42f642..fa331bf8e6de 100644
--- a/flang/lib/evaluate/tools.h
+++ b/flang/lib/evaluate/tools.h
@@ -103,7 +103,7 @@ Expr<TO> ConvertToType(Expr<SomeKind<FROMCAT>> &&x) {
     }
   } else {
     // Same type category
-    if (auto already{common::GetIf<Expr<TO>>(x.u)}) {
+    if (auto *already{std::get_if<Expr<TO>>(&x.u)}) {
       return std::move(*already);
     }
     if constexpr (TO::category == TypeCategory::Complex) {
diff --git a/flang/lib/evaluate/type.h b/flang/lib/evaluate/type.h
index de34d1e2676e..889c89798aa5 100644
--- a/flang/lib/evaluate/type.h
+++ b/flang/lib/evaluate/type.h
@@ -210,7 +210,7 @@ template<typename TYPES> struct SomeScalar {
   SomeScalar(std::enable_if_t<!std::is_reference_v<A>, A> &&x)
     : u{std::move(x)} {}
 
-  auto ToInt64() const {
+  std::optional<std::int64_t> ToInt64() const {
     return std::visit(
         [](const auto &x) -> std::optional<std::int64_t> {
           if constexpr (TypeOf<decltype(x)>::category ==
@@ -222,7 +222,7 @@ template<typename TYPES> struct SomeScalar {
         u);
   }
 
-  auto ToString() const {
+  std::optional<std::string> ToString() const {
     return std::visit(
         [](const auto &x) -> std::optional<std::string> {
           if constexpr (std::is_same_v<std::string,
@@ -234,7 +234,7 @@ template<typename TYPES> struct SomeScalar {
         u);
   }
 
-  auto IsTrue() const {
+  std::optional<bool> IsTrue() const {
     return std::visit(
         [](const auto &x) -> std::optional<bool> {
           if constexpr (TypeOf<decltype(x)>::category ==
@@ -246,10 +246,6 @@ template<typename TYPES> struct SomeScalar {
         u);
   }
 
-  template<typename T> auto GetIf() const {
-    return common::GetIf<Scalar<T>>(u);
-  }
-
   common::MapTemplate<Scalar, Types> u;
 };
 
diff --git a/flang/lib/semantics/expression.cc b/flang/lib/semantics/expression.cc
index 416f45a4f4f1..b0800a3a041d 100644
--- a/flang/lib/semantics/expression.cc
+++ b/flang/lib/semantics/expression.cc
@@ -323,9 +323,11 @@ MaybeExpr ExprAnalyzer::Analyze(const parser::RealLiteralConstant &x) {
 
 MaybeExpr ExprAnalyzer::Analyze(const parser::SignedRealLiteralConstant &x) {
   if (MaybeExpr result{Analyze(std::get<parser::RealLiteralConstant>(x.t))}) {
+    auto *realExpr{std::get_if<Expr<SomeReal>>(&result->u)};
+    CHECK(realExpr != nullptr);
     if (auto sign{std::get<std::optional<parser::Sign>>(x.t)}) {
       if (sign == parser::Sign::Negative) {
-        return {AsGenericExpr(-*common::GetIf<Expr<SomeReal>>(result->u))};
+        return {AsGenericExpr(-std::move(*realExpr))};
       }
     }
     return result;
@@ -397,32 +399,38 @@ MaybeExpr ExprAnalyzer::Analyze(const parser::BOZLiteralConstant &x) {
   return {AsGenericExpr(value.value)};
 }
 
-template<typename TYPE, TypeCategory CATEGORY>
-MaybeExpr DataRefIfType(
-    const semantics::Symbol &symbol, int defaultKind, DataRef &&dataRef) {
+template<TypeCategory CATEGORY>
+MaybeExpr TypedDataRefHelper(int kind, DataRef &&dataRef) {
+  return common::SearchDynamicTypes(
+      TypeKindVisitor<CATEGORY, DataReference, DataRef>{
+          kind, std::move(dataRef)});
+}
+
+static MaybeExpr TypedDataRef(
+    const semantics::Symbol &symbol, DataRef &&dataRef) {
   if (auto *details{symbol.detailsIf<semantics::ObjectEntityDetails>()}) {
     if (details->type().has_value()) {
       if (details->type()->category() ==
           semantics::DeclTypeSpec::Category::Intrinsic) {
-        std::uint64_t kindParam{
-            details->type()->intrinsicTypeSpec().kind().value().value()};
-        int kind = static_cast<int>(kindParam);
-        if (static_cast<std::uint64_t>(kind) == kindParam) {
-          // TODO: Inspection of semantics::IntrinsicTypeSpec requires the use
-          // of forbidden RTTI via dynamic_cast<>.  See whether
-          // semantics::IntrinsicTypeSpec can be augmented with query
-          // interfaces instead.
-          if (dynamic_cast<const TYPE *>(
-                  &details->type()->intrinsicTypeSpec()) != nullptr) {
-            if (kind == 0) {  // TODO: resolve default kinds in semantics
-              kind = defaultKind;
-            }
-            if (MaybeExpr result{common::SearchDynamicTypes(
-                    TypeKindVisitor<CATEGORY, DataReference, DataRef>{
-                        kind, std::move(dataRef)})}) {
-              return result;
-            }
-          }
+        TypeCategory category{details->type()->intrinsicTypeSpec().category()};
+        int kind{details->type()->intrinsicTypeSpec().kind()};
+        switch (category) {
+        case TypeCategory::Integer:
+          return TypedDataRefHelper<TypeCategory::Integer>(
+              kind, std::move(dataRef));
+        case TypeCategory::Real:
+          return TypedDataRefHelper<TypeCategory::Real>(
+              kind, std::move(dataRef));
+        case TypeCategory::Complex:
+          return TypedDataRefHelper<TypeCategory::Complex>(
+              kind, std::move(dataRef));
+        case TypeCategory::Character:
+          return TypedDataRefHelper<TypeCategory::Character>(
+              kind, std::move(dataRef));
+        case TypeCategory::Logical:
+          return TypedDataRefHelper<TypeCategory::Logical>(
+              kind, std::move(dataRef));
+        default: CRASH_NO_CASE;
         }
       }
     }
@@ -430,36 +438,6 @@ MaybeExpr DataRefIfType(
   return std::nullopt;
 }
 
-static MaybeExpr TypedDataRef(const semantics::Symbol &symbol,
-    const semantics::IntrinsicTypeDefaultKinds &defaults, DataRef &&dataRef) {
-  if (MaybeExpr result{
-          DataRefIfType<semantics::IntegerTypeSpec, TypeCategory::Integer>(
-              symbol, defaults.defaultIntegerKind, std::move(dataRef))}) {
-    return result;
-  }
-  if (MaybeExpr result{
-          DataRefIfType<semantics::RealTypeSpec, TypeCategory::Real>(
-              symbol, defaults.defaultRealKind, std::move(dataRef))}) {
-    return result;
-  }
-  if (MaybeExpr result{
-          DataRefIfType<semantics::ComplexTypeSpec, TypeCategory::Complex>(
-              symbol, defaults.defaultRealKind, std::move(dataRef))}) {
-    return result;
-  }
-  if (MaybeExpr result{
-          DataRefIfType<semantics::CharacterTypeSpec, TypeCategory::Character>(
-              symbol, defaults.defaultCharacterKind, std::move(dataRef))}) {
-    return result;
-  }
-  if (MaybeExpr result{
-          DataRefIfType<semantics::LogicalTypeSpec, TypeCategory::Logical>(
-              symbol, defaults.defaultLogicalKind, std::move(dataRef))}) {
-    return result;
-  }
-  return std::nullopt;
-}
-
 MaybeExpr ExprAnalyzer::Analyze(const parser::Name &n) {
   if (n.symbol == nullptr) {
     // TODO: convert this to a CHECK later
@@ -471,8 +449,7 @@ MaybeExpr ExprAnalyzer::Analyze(const parser::Name &n) {
         "TODO: PARAMETER references not yet implemented"_err_en_US);
     // TODO: enumerators, do they have the PARAMETER attribute?
   } else {
-    if (MaybeExpr result{
-            TypedDataRef(*n.symbol, defaults, DataRef{*n.symbol})}) {
+    if (MaybeExpr result{TypedDataRef(*n.symbol, DataRef{*n.symbol})}) {
       return result;
     }
     context.messages.Say("'%s' is not of a supported type and kind"_err_en_US,
@@ -562,8 +539,7 @@ MaybeExpr ExprAnalyzer::Analyze(const parser::ArrayElement &ae) {
           name->ToString().data());
     } else {
       ArrayRef arrayRef{*name->symbol, std::move(subscripts)};
-      return TypedDataRef(
-          *name->symbol, defaults, DataRef{std::move(arrayRef)});
+      return TypedDataRef(*name->symbol, DataRef{std::move(arrayRef)});
     }
   } else if (const auto *component{
                  std::get_if<common::Indirection<parser::StructureComponent>>(