[flang] Emit "raw" name for procedure interface in module file (#83915)

Save both the raw procedure interface symbol as well as the result of
passing it through GetUltimate() and BypassGeneric() in symbol table
entries with ProcEntityDetails. The raw symbol of the interface needs to
be the one used for emitting procedure symbols to module files.

Fixes #83836.

Author: klausler

flang/include/flang/Semantics/symbol.h

@@ -417,8 +417,12 @@ class ProcEntityDetails : public EntityDetails, public WithPassArg {
   ProcEntityDetails(ProcEntityDetails &&) = default;
   ProcEntityDetails &operator=(const ProcEntityDetails &) = default;
 
+  const Symbol *rawProcInterface() const { return rawProcInterface_; }
   const Symbol *procInterface() const { return procInterface_; }
-  void set_procInterface(const Symbol &sym) { procInterface_ = &sym; }
+  void set_procInterfaces(const Symbol &raw, const Symbol &resolved) {
+    rawProcInterface_ = &raw;
+    procInterface_ = &resolved;
+  }
   inline bool HasExplicitInterface() const;
 
   // Be advised: !init().has_value() => uninitialized pointer,
@@ -430,6 +434,7 @@ class ProcEntityDetails : public EntityDetails, public WithPassArg {
   void set_isCUDAKernel(bool yes = true) { isCUDAKernel_ = yes; }
 
 private:
+  const Symbol *rawProcInterface_{nullptr};
   const Symbol *procInterface_{nullptr};
   std::optional<const Symbol *> init_;
   bool isCUDAKernel_{false};

flang/lib/Semantics/check-declarations.cpp

@@ -1195,9 +1195,7 @@ void CheckHelper::CheckArraySpec(
 void CheckHelper::CheckProcEntity(
     const Symbol &symbol, const ProcEntityDetails &details) {
   CheckSymbolType(symbol);
-  const Symbol *interface {
-    details.procInterface() ? &details.procInterface()->GetUltimate() : nullptr
-  };
+  const Symbol *interface{details.procInterface()};
   if (details.isDummy()) {
     if (!symbol.attrs().test(Attr::POINTER) && // C843
         (symbol.attrs().test(Attr::INTENT_IN) ||

flang/lib/Semantics/mod-file.cpp

@@ -924,8 +924,8 @@ void ModFileWriter::PutProcEntity(llvm::raw_ostream &os, const Symbol &symbol) {
       os, symbol,
       [&]() {
         os << "procedure(";
-        if (details.procInterface()) {
-          os << details.procInterface()->name();
+        if (details.rawProcInterface()) {
+          os << details.rawProcInterface()->name();
         } else if (details.type()) {
           PutType(os, *details.type());
         }
@@ -1622,8 +1622,8 @@ void SubprogramSymbolCollector::DoSymbol(
                       }
                     },
                     [this](const ProcEntityDetails &details) {
-                      if (details.procInterface()) {
-                        DoSymbol(*details.procInterface());
+                      if (details.rawProcInterface()) {
+                        DoSymbol(*details.rawProcInterface());
                       } else {
                         DoType(details.type());
                       }

flang/lib/Semantics/resolve-names-utils.cpp

@@ -845,8 +845,9 @@ void SymbolMapper::MapSymbolExprs(Symbol &symbol) {
                        },
           [&](ProcEntityDetails &proc) {
             if (const Symbol *
-                mappedSymbol{MapInterface(proc.procInterface())}) {
-              proc.set_procInterface(*mappedSymbol);
+                mappedSymbol{MapInterface(proc.rawProcInterface())}) {
+              proc.set_procInterfaces(
+                  *mappedSymbol, BypassGeneric(mappedSymbol->GetUltimate()));
             } else if (const DeclTypeSpec * mappedType{MapType(proc.type())}) {
               proc.set_type(*mappedType);
             }

flang/lib/Semantics/resolve-names.cpp

@@ -4983,7 +4983,8 @@ Symbol &DeclarationVisitor::DeclareProcEntity(
           "The interface for procedure '%s' has already been declared"_err_en_US);
       context().SetError(symbol);
     } else if (interface) {
-      details->set_procInterface(*interface);
+      details->set_procInterfaces(
+          *interface, BypassGeneric(interface->GetUltimate()));
       if (interface->test(Symbol::Flag::Function)) {
         symbol.set(Symbol::Flag::Function);
       } else if (interface->test(Symbol::Flag::Subroutine)) {
@@ -5658,10 +5659,10 @@ void DeclarationVisitor::Post(const parser::ProcInterface &x) {
 }
 void DeclarationVisitor::Post(const parser::ProcDecl &x) {
   const auto &name{std::get<parser::Name>(x.t)};
-  const Symbol *procInterface{nullptr};
-  if (interfaceName_ && interfaceName_->symbol) {
-    procInterface = &BypassGeneric(*interfaceName_->symbol);
-  }
+  // Don't use BypassGeneric or GetUltimate on this symbol, they can
+  // lead to unusable names in module files.
+  const Symbol *procInterface{
+      interfaceName_ ? interfaceName_->symbol : nullptr};
   auto attrs{HandleSaveName(name.source, GetAttrs())};
   DerivedTypeDetails *dtDetails{nullptr};
   if (Symbol * symbol{currScope().symbol()}) {
@@ -6624,10 +6625,9 @@ void DeclarationVisitor::CheckExplicitInterface(const parser::Name &name) {
   if (const Symbol * symbol{name.symbol}) {
     const Symbol &ultimate{symbol->GetUltimate()};
     if (!context().HasError(*symbol) && !context().HasError(ultimate) &&
-        !ultimate.HasExplicitInterface()) {
+        !BypassGeneric(ultimate).HasExplicitInterface()) {
       Say(name,
-          "'%s' must be an abstract interface or a procedure with "
-          "an explicit interface"_err_en_US,
+          "'%s' must be an abstract interface or a procedure with an explicit interface"_err_en_US,
           symbol->name());
     }
   }

flang/lib/Semantics/symbol.cpp

@@ -452,6 +452,9 @@ llvm::raw_ostream &operator<<(
 llvm::raw_ostream &operator<<(
     llvm::raw_ostream &os, const ProcEntityDetails &x) {
   if (x.procInterface_) {
+    if (x.rawProcInterface_ != x.procInterface_) {
+      os << ' ' << x.rawProcInterface_->name() << " ->";
+    }
     os << ' ' << x.procInterface_->name();
   } else {
     DumpType(os, x.type());

flang/lib/Semantics/tools.cpp

@@ -465,9 +465,7 @@ const Symbol *FindInterface(const Symbol &symbol) {
   return common::visit(
       common::visitors{
           [](const ProcEntityDetails &details) {
-            const Symbol *interface {
-              details.procInterface()
-            };
+            const Symbol *interface{details.procInterface()};
             return interface ? FindInterface(*interface) : nullptr;
           },
           [](const ProcBindingDetails &details) {

flang/test/Semantics/modfile64.f90

@@ -0,0 +1,29 @@
+! RUN: %python %S/test_modfile.py %s %flang_fc1
+module mod0
+  interface proc
+    module procedure proc
+  end interface
+ contains
+  subroutine proc
+  end
+end
+module mod1
+  use mod0,renamed_proc=>proc
+  procedure(renamed_proc),pointer :: p
+end module
+
+!Expect: mod0.mod
+!module mod0
+!interface proc
+!procedure::proc
+!end interface
+!contains
+!subroutine proc()
+!end
+!end
+
+!Expect: mod1.mod
+!module mod1
+!use mod0,only:renamed_proc=>proc
+!procedure(renamed_proc),pointer::p
+!end