[flang][cuda][openacc] Emit an error when CUDA symbols are imported with CUDA disabled (#205427)

Only look for for module symbols.

flang/lib/Semantics/mod-file.cpp

@@ -70,6 +70,7 @@ static bool FileContentsMatch(
     const std::string &, const std::string &, const std::string &);
 static ModuleCheckSumType ComputeCheckSum(const std::string_view &);
 static std::string CheckSumString(ModuleCheckSumType);
+static bool ScopeHasCUDAModuleVariables(const Scope &);
 
 // Collect symbols needed for a subprogram interface
 class SubprogramSymbolCollector {
@@ -1820,6 +1821,14 @@ Scope *ModFileReader::Read(SourceName name, std::optional<bool> isIntrinsic,
     if (isIntrinsic.value_or(false)) {
       moduleSymbol->attrs().set(Attr::INTRINSIC);
     }
+    if (context_.languageFeatures().IsEnabled(
+            common::LanguageFeature::OpenACC) &&
+        !context_.languageFeatures().IsEnabled(common::LanguageFeature::CUDA) &&
+        ScopeHasCUDAModuleVariables(*moduleSymbol->scope())) {
+      Say("use", name, ancestorName,
+          "CUDA is not enabled, but '%s' defines CUDA symbols"_err_en_US,
+          sourceFile->path());
+    }
     return moduleSymbol->scope();
   } else {
     return nullptr;
@@ -1855,6 +1864,25 @@ static std::optional<SourceName> GetSubmoduleParent(
   }
 }
 
+static bool ScopeHasCUDAModuleVariables(const Scope &scope) {
+  for (const auto &[_, symbolRef] : scope) {
+    const Symbol &symbol{*symbolRef};
+    if (const auto *object{symbol.detailsIf<ObjectEntityDetails>()}) {
+      if (object->cudaDataAttr()) {
+        return true;
+      }
+      const DeclTypeSpec *type{object->type()};
+      const DerivedTypeSpec *derived{type ? type->AsDerived() : nullptr};
+      if (derived &&
+          FindUltimateComponent(*derived,
+              [](const Symbol &component) { return HasCUDAAttr(component); })) {
+        return true;
+      }
+    }
+  }
+  return false;
+}
+
 void SubprogramSymbolCollector::Collect() {
   const auto &details{symbol_.get<SubprogramDetails>()};
   isInterface_ = details.isInterface();

flang/test/Semantics/modfile84.f90

@@ -0,0 +1,46 @@
+! RUN: split-file %s %t
+! RUN: %flang_fc1 -fsyntax-only -x cuda -module-dir %t %t/m.cuf
+! RUN: not %flang_fc1 -fsyntax-only -fopenacc -module-dir %t %t/use.f90 2>&1 | FileCheck %s
+! RUN: %flang_fc1 -fsyntax-only -x cuda -module-dir %t %t/m2.cuf
+! RUN: %flang_fc1 -fsyntax-only -fopenacc -module-dir %t %t/use2.f90
+! RUN: %flang_fc1 -fsyntax-only -x cuda -module-dir %t %t/m3.cuf
+! RUN: not %flang_fc1 -fsyntax-only -fopenacc -module-dir %t %t/use3.f90 2>&1 | FileCheck --check-prefix=CHECK-M3 %s
+
+!--- m.cuf
+module modfile84m
+  real, device :: d
+contains
+  attributes(device) subroutine s()
+  end subroutine
+end module
+
+!--- m2.cuf
+module modfile84m2
+contains
+  attributes(device) subroutine s()
+  end subroutine
+end module
+
+!--- m3.cuf
+module modfile84m3
+  type dt
+    real, device, pointer :: dp
+  end type
+
+  type(dt) :: d ! Should trigger the error
+end module
+
+!--- use.f90
+use modfile84m
+end
+
+!--- use2.f90
+use modfile84m2
+end
+
+!--- use3.f90
+use modfile84m3
+end
+
+! CHECK: error: Cannot use module file for module 'modfile84m': CUDA is not enabled, but '{{.*modfile84m.mod}}' defines CUDA symbols
+! CHECK-M3: error: Cannot use module file for module 'modfile84m3': CUDA is not enabled, but '{{.*modfile84m3.mod}}' defines CUDA symbols