[flang] Silence spurious error on non-CUDA use of CUDA module (#107444)

When a module file has been compiled with CUDA enabled, don't emit
spurious errors about non-interoperable types when that module is read
by a USE statement in a later non-CUDA compilation.

flang/include/flang/Semantics/type.h

@@ -459,8 +459,5 @@ inline const DerivedTypeSpec *DeclTypeSpec::AsDerived() const {
   return const_cast<DeclTypeSpec *>(this)->AsDerived();
 }
 
-std::optional<bool> IsInteroperableIntrinsicType(
-    const DeclTypeSpec &, const common::LanguageFeatureControl &);
-
 } // namespace Fortran::semantics
 #endif // FORTRAN_SEMANTICS_TYPE_H_

flang/lib/Evaluate/type.cpp

@@ -820,8 +820,8 @@ std::optional<bool> IsInteroperableIntrinsicType(const DynamicType &type,
     return true;
   case TypeCategory::Real:
   case TypeCategory::Complex:
-    return (features && features->IsEnabled(common::LanguageFeature::CUDA)) ||
-        type.kind() >= 4; // no short or half floats
+    return type.kind() >= 4 /* not a short or half float */ || !features ||
+        features->IsEnabled(common::LanguageFeature::CUDA);
   case TypeCategory::Logical:
     return type.kind() == 1; // C_BOOL
   case TypeCategory::Character:

flang/lib/Semantics/check-declarations.cpp

@@ -3003,17 +3003,17 @@ parser::Messages CheckHelper::WhyNotInteroperableDerivedType(
           } else {
             msgs.Annex(std::move(bad));
           }
-        } else if (!IsInteroperableIntrinsicType(
-                       *type, context_.languageFeatures())
+        } else if (auto dyType{evaluate::DynamicType::From(*type)}; dyType &&
+                   !evaluate::IsInteroperableIntrinsicType(
+                       *dyType, &context_.languageFeatures())
                         .value_or(false)) {
-          auto maybeDyType{evaluate::DynamicType::From(*type)};
           if (type->category() == DeclTypeSpec::Logical) {
             if (context_.ShouldWarn(common::UsageWarning::LogicalVsCBool)) {
               msgs.Say(component.name(),
                   "A LOGICAL component of an interoperable type should have the interoperable KIND=C_BOOL"_port_en_US);
             }
-          } else if (type->category() == DeclTypeSpec::Character &&
-              maybeDyType && maybeDyType->kind() == 1) {
+          } else if (type->category() == DeclTypeSpec::Character && dyType &&
+              dyType->kind() == 1) {
             if (context_.ShouldWarn(common::UsageWarning::BindCCharLength)) {
               msgs.Say(component.name(),
                   "A CHARACTER component of an interoperable type should have length 1"_port_en_US);
@@ -3106,10 +3106,15 @@ parser::Messages CheckHelper::WhyNotInteroperableObject(const Symbol &symbol) {
         type->category() == DeclTypeSpec::Character &&
         type->characterTypeSpec().length().isDeferred()) {
       // ok; F'2023 18.3.7 p2(6)
-    } else if (derived ||
-        IsInteroperableIntrinsicType(*type, context_.languageFeatures())
-            .value_or(false)) {
+    } else if (derived) { // type has been checked
+    } else if (auto dyType{evaluate::DynamicType::From(*type)}; dyType &&
+               evaluate::IsInteroperableIntrinsicType(*dyType,
+                   InModuleFile() ? nullptr : &context_.languageFeatures())
+                   .value_or(false)) {
       // F'2023 18.3.7 p2(4,5)
+      // N.B. Language features are not passed to IsInteroperableIntrinsicType
+      // when processing a module file, since the module file might have been
+      // compiled with CUDA while the client is not.
     } else if (type->category() == DeclTypeSpec::Logical) {
       if (context_.ShouldWarn(common::UsageWarning::LogicalVsCBool) &&
           !InModuleFile()) {

flang/lib/Semantics/expression.cpp

@@ -1956,7 +1956,7 @@ MaybeExpr ExpressionAnalyzer::Analyze(const parser::ArrayConstructor &array) {
 
 // Check if implicit conversion of expr to the symbol type is legal (if needed),
 // and make it explicit if requested.
-static MaybeExpr implicitConvertTo(const semantics::Symbol &sym,
+static MaybeExpr ImplicitConvertTo(const semantics::Symbol &sym,
     Expr<SomeType> &&expr, bool keepConvertImplicit) {
   if (!keepConvertImplicit) {
     return ConvertToType(sym, std::move(expr));
@@ -2196,7 +2196,7 @@ MaybeExpr ExpressionAnalyzer::Analyze(
         // convert would cause a segfault. Lowering will deal with
         // conditionally converting and preserving the lower bounds in this
         // case.
-        if (MaybeExpr converted{implicitConvertTo(
+        if (MaybeExpr converted{ImplicitConvertTo(
                 *symbol, std::move(*value), IsAllocatable(*symbol))}) {
           if (auto componentShape{GetShape(GetFoldingContext(), *symbol)}) {
             if (auto valueShape{GetShape(GetFoldingContext(), *converted)}) {

flang/lib/Semantics/type.cpp

@@ -893,13 +893,4 @@ llvm::raw_ostream &operator<<(llvm::raw_ostream &o, const DeclTypeSpec &x) {
   return o << x.AsFortran();
 }
 
-std::optional<bool> IsInteroperableIntrinsicType(
-    const DeclTypeSpec &type, const common::LanguageFeatureControl &features) {
-  if (auto dyType{evaluate::DynamicType::From(type)}) {
-    return IsInteroperableIntrinsicType(*dyType, &features);
-  } else {
-    return std::nullopt;
-  }
-}
-
 } // namespace Fortran::semantics

flang/test/Semantics/Inputs/modfile66.cuf

@@ -0,0 +1,4 @@
+module usereal2
+  !REAL(2) is interoperable under CUDA
+  real(2), bind(c) :: x
+end

flang/test/Semantics/modfile66.f90

@@ -0,0 +1,3 @@
+! RUN: %flang_fc1 -fsyntax-only %S/Inputs/modfile66.cuf && %flang_fc1 -fsyntax-only %s
+use usereal2 ! valid since x is not used
+end