From 5e65aaa921f18cb3d9ff3ac11dc0a568f5e3d10e Mon Sep 17 00:00:00 2001
From: Tim Keith <tkeith@nvidia.com>
Date: Thu, 22 Aug 2019 13:57:18 -0700
Subject: [PATCH] [flang] Fix .mod file bug with IMPORT of USEd name

If a symbol (derived type, for example) was use-associated into a scope
and then imported into a nested interface block, we were not including
the correct IMPORT statement in the .mod file.

This fixes refines the test for when the IMPORT is needed.

Fixes flang-compiler/f18#657.

Original-commit: flang-compiler/f18@8383de47ecb1b6901e2dd6f290df28fe8a470908
Reviewed-on: https://github.com/flang-compiler/f18/pull/675
Tree-same-pre-rewrite: false
---
 flang/lib/semantics/mod-file.cc    | 17 ++++++++++++++++-
 flang/test/semantics/modfile23.f90 | 31 +++++++++++++++++++++++++++++++
 2 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/flang/lib/semantics/mod-file.cc b/flang/lib/semantics/mod-file.cc
index 7845b24..711caae 100644
--- a/flang/lib/semantics/mod-file.cc
+++ b/flang/lib/semantics/mod-file.cc
@@ -86,6 +86,7 @@ private:
   void DoType(const DeclTypeSpec *);
   void DoBound(const Bound &);
   void DoParamValue(const ParamValue &);
+  bool NeedImport(const Symbol &);
 
   struct SymbolVisitor : public virtual evaluate::VisitorBase<SymbolVector> {
     using Result = SymbolVector;
@@ -824,7 +825,8 @@ void SubprogramSymbolCollector::DoSymbol(const Symbol &symbol) {
   if (scope != scope_ && !scope.IsDerivedType()) {
     if (scope != scope_.parent()) {
       useSet_.insert(&symbol);
-    } else if (isInterface_) {
+    }
+    if (NeedImport(symbol)) {
       imports_.insert(&symbol);
     }
     return;
@@ -902,4 +904,17 @@ void SubprogramSymbolCollector::DoParamValue(const ParamValue &paramValue) {
   }
 }
 
+// Do we need a IMPORT of this symbol into an interface block?
+bool SubprogramSymbolCollector::NeedImport(const Symbol &symbol) {
+  if (!isInterface_) {
+    return false;
+  } else if (symbol.owner() != scope_.parent()) {
+    // detect import from parent of use-associated symbol
+    const auto *found{scope_.FindSymbol(symbol.name())};
+    return DEREF(found).has<UseDetails>() && found->owner() != scope_;
+  } else {
+    return true;
+  }
+}
+
 }
diff --git a/flang/test/semantics/modfile23.f90 b/flang/test/semantics/modfile23.f90
index ca24a6a..8e651d4 100644
--- a/flang/test/semantics/modfile23.f90
+++ b/flang/test/semantics/modfile23.f90
@@ -184,3 +184,34 @@ end
 !  character(i,1)::x
 ! end
 !end
+
+module m8
+  use m1, only: t1, t2
+  interface
+    subroutine s1(x)
+      import
+      type(t1) :: x
+    end subroutine
+    subroutine s2(x)
+      import :: t2
+      type(t2) :: x
+    end subroutine
+  end interface
+end
+!Expect: m8.mod
+!module m8
+! use m1,only:t1
+! use m1,only:t2
+! interface
+!  subroutine s1(x)
+!   import::t1
+!   type(t1)::x
+!  end
+! end interface
+! interface
+!  subroutine s2(x)
+!   import::t2
+!   type(t2)::x
+!  end
+! end interface
+!end
-- 
2.7.4