[AddOrUpdateCommonBlockUse] Implemented selection of largest COMMON block in case of uses from multiple modules, except that it doesn't work: COMMON block sizes are computed after the name resolution

Author: eugeneepshteyn

flang/include/flang/Semantics/scope.h

@@ -194,7 +194,7 @@ class Scope {
   const mapType &crayPointers() const { return crayPointers_; }
   void add_crayPointer(const SourceName &, Symbol &);
   Symbol &MakeCommonBlock(SourceName, SourceName location);
-  bool AddOrUpdateCommonBlockUse(const SourceName &name, Attrs attrs, Symbol& cbUltimate);
+  bool AddCommonBlockUse(const SourceName &name, Attrs attrs, Symbol& cbUltimate);
 
   // Find COMMON block that is declared in the current scope
   Symbol *FindCommonBlock(const SourceName &name) const {

flang/lib/Semantics/resolve-names.cpp

@@ -3631,14 +3631,14 @@ void ModuleVisitor::Post(const parser::UseStmt &x) {
   // their USE association to the current scope's USE-associated COMMON blocks.
   for (const auto &[name, symbol] : useModuleScope_->commonBlocks()) {
     if (!currScope().FindCommonBlockInVisibleScopes(name)) {
-      currScope().AddOrUpdateCommonBlockUse(name, symbol->attrs(), symbol->GetUltimate());
+      currScope().AddCommonBlockUse(name, symbol->attrs(), symbol->GetUltimate());
     }
   }
   // Go through the list of USE-associated COMMON block symbols in the module
   // scope and add USE associations to their ultimate symbols to the current
   // scope's USE-associated COMMON blocks.
   for (const auto &[name, symbol] : useModuleScope_->commonBlockUses()) {
-    currScope().AddOrUpdateCommonBlockUse(name, symbol->attrs(), symbol->GetUltimate());
+    currScope().AddCommonBlockUse(name, symbol->attrs(), symbol->GetUltimate());
   }
   useModuleScope_ = nullptr;
 }

flang/lib/Semantics/scope.cpp

@@ -183,24 +183,12 @@ Scope *Scope::FindSubmodule(const SourceName &name) const {
   }
 }
 
-bool Scope::AddOrUpdateCommonBlockUse(const SourceName &name, Attrs attrs, Symbol& cbUltimate) {
+bool Scope::AddCommonBlockUse(const SourceName &name, Attrs attrs, Symbol& cbUltimate) {
   CHECK(cbUltimate.has<CommonBlockDetails>());
-  if (Symbol *cb{FindCommonBlockUse(name)}) {
-    // We already stored UseDetails from the previous encounter with the
-    // same named COMMON block (perhaps it came from a different module).
-    // Ensure that we store USE association to the largest COMMON block,
-    // which is presumably is better defined.
-    Symbol &cbExistingUltimate{cb->GetUltimate()};
-    if (cbExistingUltimate.size() < cbUltimate.size()) {
-      cb->set_details(UseDetails{name, cbUltimate});
-    }
-    return true;
-  } else {
-    // Make a symbol, but don't add it to the Scope, since it needs to
-    // be added to the USE-associated COMMON blocks
-    Symbol &useCB{MakeSymbol(name, attrs, UseDetails{name, cbUltimate})};
-    return commonBlockUses_.emplace(name, useCB).second;
-  }
+  // Make a symbol, but don't add it to the Scope, since it needs to
+  // be added to the USE-associated COMMON blocks
+  Symbol &useCB{MakeSymbol(name, attrs, UseDetails{name, cbUltimate})};
+  return commonBlockUses_.emplace(name, useCB).second;
 }
 
 bool Scope::AddSubmodule(const SourceName &name, Scope &submodule) {

flang/lib/Semantics/symbol.cpp

@@ -373,16 +373,7 @@ bool Symbol::CanReplaceDetails(const Details &details) const {
             },
             [&](const UseDetails &x) {
               const auto *use{this->detailsIf<UseDetails>()};
-              if (!use) {
-                return false;
-              } else if (use->symbol().detailsIf<CommonBlockDetails>() &&
-                  x.symbol().detailsIf<CommonBlockDetails>()) {
-                // Allow to replace UseDetails, if they both refer to COMMON
-                // symbol with the same name.
-                return use->symbol().name() == x.symbol().name();
-              } else {
-                return use->symbol() == x.symbol();
-              }
+              return use && use->symbol() == x.symbol();
             },
             [&](const HostAssocDetails &) { return has<HostAssocDetails>(); },
             [&](const UserReductionDetails &) {