[flang] Don't repeat module procedure interface from ancestor in *.mod file

When a submodule defines a module procedure whose interface was declared
in an ancestor (sub)module, don't repeat the definition of that interface
in the submodule's *.mod file output.

Differential Revision: https://reviews.llvm.org/D139132

1 files changed, 6 insertions, 1 deletions

diff --git a/flang/lib/Semantics/mod-file.cpp b/flang/lib/Semantics/mod-file.cpp
index 0f6117b..36b2341 100644
--- a/flang/lib/Semantics/mod-file.cpp
+++ b/flang/lib/Semantics/mod-file.cpp
@@ -422,7 +422,12 @@ static const Attrs subprogramPrefixAttrs{Attr::ELEMENTAL, Attr::IMPURE,
 void ModFileWriter::PutSubprogram(const Symbol &symbol) {
   auto &details{symbol.get<SubprogramDetails>()};
   if (const Symbol * interface{details.moduleInterface()}) {
-    PutSubprogram(*interface);
+    const Scope *module{FindModuleContaining(interface->owner())};
+    if (module && module != &symbol.owner()) {
+      // Interface is in ancestor module
+    } else {
+      PutSubprogram(*interface);
+    }
   }
   auto attrs{symbol.attrs()};
   Attrs bindAttrs{};