flang/lib/Semantics/check-return.cpp

   1 //===-- lib/Semantics/check-return.cpp ------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "check-return.h"
  10 #include "flang/Common/Fortran-features.h"
  11 #include "flang/Parser/message.h"
  12 #include "flang/Parser/parse-tree.h"
  13 #include "flang/Semantics/semantics.h"
  14 #include "flang/Semantics/tools.h"
  15
  16 namespace Fortran::semantics {
  17
  18 static const Scope *FindContainingSubprogram(const Scope &start) {
  19   const Scope &scope{GetProgramUnitContaining(start)};
  20   return scope.kind() == Scope::Kind::MainProgram ||
  21           scope.kind() == Scope::Kind::Subprogram
  22       ? &scope
  23       : nullptr;
  24 }
  25
  26 void ReturnStmtChecker::Leave(const parser::ReturnStmt &returnStmt) {
  27   // R1542 Expression analysis validates the scalar-int-expr
  28   // C1574 The return-stmt shall be in the inclusive scope of a function or
  29   // subroutine subprogram.
  30   // C1575 The scalar-int-expr is allowed only in the inclusive scope of a
  31   // subroutine subprogram.
  32   const auto &scope{context_.FindScope(context_.location().value())};
  33   if (const auto *subprogramScope{FindContainingSubprogram(scope)}) {
  34     if (returnStmt.v &&
  35         (subprogramScope->kind() == Scope::Kind::MainProgram ||
  36             IsFunction(*subprogramScope->GetSymbol()))) {
  37       context_.Say(
  38           "RETURN with expression is only allowed in SUBROUTINE subprogram"_err_en_US);
  39     } else if (subprogramScope->kind() == Scope::Kind::MainProgram &&
  40         context_.ShouldWarn(common::LanguageFeature::ProgramReturn)) {
  41       context_.Say("RETURN should not appear in a main program"_port_en_US);
  42     }
  43   }
  44 }
  45
  46 } // namespace Fortran::semantics