[flang] Enforce accessibility requirement on type-bound generic operators, &c.

[klausler]

Summary

Type-bound generics like operator(+) and assignment(=) need to not be
PRIVATE if they are used outside the module in which they are declared.

[klausler]

clang-format entire Semantics/expression.cpp file to get past CI

flang/include/flang/Semantics/scope.h

   const Scope *GetDerivedTypeParent() const;
   const Scope &GetDerivedTypeBase() const;
   inline std::optional<SourceName> GetName() const;
+  // Returns true if this scope contains, or is, another scope.
   bool Contains(const Scope &) const;
   /// Make a scope nested in this one
   Scope &MakeScope(Kind kind, Symbol *symbol = nullptr);

flang/include/flang/Semantics/tools.h

 bool IsGenericDefinedOp(const Symbol &);
 bool IsDefinedOperator(SourceName);
 std::string MakeOpName(SourceName);
+
+// Returns true if maybeAncestor exists and is a proper ancestor of a
+// descendent scope (or symbol owner).  Will be false, unlike Scope::Contains(),
+// if maybeAncestor *is* the descendent.
 bool DoesScopeContain(const Scope *maybeAncestor, const Scope &maybeDescendent);
 bool DoesScopeContain(const Scope *, const Symbol &);
+
 bool IsUseAssociated(const Symbol &, const Scope &);
 bool IsHostAssociated(const Symbol &, const Scope &);
 bool IsHostAssociatedIntoSubprogram(const Symbol &, const Scope &);

 bool IsAssumedType(const Symbol &);
 bool IsPolymorphic(const Symbol &);
 bool IsPolymorphicAllocatable(const Symbol &);
-// Return an error if component symbol is not accessible from scope (7.5.4.8(2))
-std::optional<parser::MessageFormattedText> CheckAccessibleComponent(
+
+// Return an error if a symbol is not accessible from a scope
+std::optional<parser::MessageFormattedText> CheckAccessibleSymbol(
     const semantics::Scope &, const Symbol &);
 
 // Analysis of image control statements

flang/lib/Semantics/expression.cpp

 
   // Find and return a user-defined operator or report an error.
   // The provided message is used if there is no such operator.
-  MaybeExpr TryDefinedOp(const char *, parser::MessageFixedText,
-      const Symbol **definedOpSymbolPtr = nullptr, bool isUserOp = false);
+  // If a definedOpSymbolPtr is provided, the caller must check
+  // for its accessibility.
+  MaybeExpr TryDefinedOp(
+      const char *, parser::MessageFixedText, bool isUserOp = false);
   template <typename E>
   MaybeExpr TryDefinedOp(E opr, parser::MessageFixedText msg) {
     return TryDefinedOp(

   std::optional<ActualArgument> AnalyzeExpr(const parser::Expr &);
   MaybeExpr AnalyzeExprOrWholeAssumedSizeArray(const parser::Expr &);
   bool AreConformable() const;
-  const Symbol *FindBoundOp(
-      parser::CharBlock, int passIndex, const Symbol *&definedOp);
+  const Symbol *FindBoundOp(parser::CharBlock, int passIndex,
+      const Symbol *&generic, bool isSubroutine);
   void AddAssignmentConversion(
       const DynamicType &lhsType, const DynamicType &rhsType);
   bool OkLogicalIntegerAssignment(TypeCategory lhs, TypeCategory rhs);

       }
     }
     if (symbol) {
-      if (const auto *currScope{context_.globalScope().FindScope(source)}) {
-        if (auto msg{CheckAccessibleComponent(*currScope, *symbol)}) {
-          Say(source, *msg);
-        }
+      const semantics::Scope &innermost{context_.FindScope(expr.source)};
+      if (auto msg{CheckAccessibleSymbol(innermost, *symbol)}) {
+        Say(expr.source, std::move(*msg));
       }
       if (checkConflicts) {
         auto componentIter{

       }
       unavailable.insert(symbol->name());
       if (value) {
-        const auto &innermost{context_.FindScope(expr.source)};
         if (symbol->has<semantics::ProcEntityDetails>()) {
           CHECK(IsPointer(*symbol));
         } else if (symbol->has<semantics::ObjectEntityDetails>()) {

   ArgumentAnalyzer analyzer{*this, name.source};
   analyzer.Analyze(std::get<1>(x.t));
   return analyzer.TryDefinedOp(name.source.ToString().c_str(),
-      "No operator %s defined for %s"_err_en_US, nullptr, true);
+      "No operator %s defined for %s"_err_en_US, true);
 }
 
 // Binary (dyadic) operations

   analyzer.Analyze(std::get<1>(x.t));
   analyzer.Analyze(std::get<2>(x.t));
   return analyzer.TryDefinedOp(name.source.ToString().c_str(),
-      "No operator %s defined for %s and %s"_err_en_US, nullptr, true);
+      "No operator %s defined for %s and %s"_err_en_US, true);
 }
 
 // Returns true if a parsed function reference should be converted

   return true;
 }
 
-MaybeExpr ArgumentAnalyzer::TryDefinedOp(const char *opr,
-    parser::MessageFixedText error, const Symbol **definedOpSymbolPtr,
-    bool isUserOp) {
+MaybeExpr ArgumentAnalyzer::TryDefinedOp(
+    const char *opr, parser::MessageFixedText error, bool isUserOp) {
   if (AnyUntypedOrMissingOperand()) {
     context_.Say(error, ToUpperCase(opr), TypeAsFortran(0), TypeAsFortran(1));
     return std::nullopt;
   }
-  const Symbol *localDefinedOpSymbolPtr{nullptr};
-  if (!definedOpSymbolPtr) {
-    definedOpSymbolPtr = &localDefinedOpSymbolPtr;
-  }
+  MaybeExpr result;
+  bool anyPossibilities{false};
+  std::optional<parser::MessageFormattedText> inaccessible;
+  std::vector<const Symbol *> hit;
+  std::string oprNameString{
+      isUserOp ? std::string{opr} : "operator("s + opr + ')'};
+  parser::CharBlock oprName{oprNameString};
   {
     auto restorer{context_.GetContextualMessages().DiscardMessages()};
-    std::string oprNameString{
-        isUserOp ? std::string{opr} : "operator("s + opr + ')'};
-    parser::CharBlock oprName{oprNameString};
     const auto &scope{context_.context().FindScope(source_)};
     if (Symbol * symbol{scope.FindSymbol(oprName)}) {
-      *definedOpSymbolPtr = symbol;
+      anyPossibilities = true;
       parser::Name name{symbol->name(), symbol};
-      if (auto result{context_.AnalyzeDefinedOp(name, GetActuals())}) {
-        return result;
+      result = context_.AnalyzeDefinedOp(name, GetActuals());
+      if (result) {
+        inaccessible = CheckAccessibleSymbol(scope, *symbol);
+        if (inaccessible) {
+          result.reset();
+        } else {
+          hit.push_back(symbol);
+        }
       }
     }
     for (std::size_t passIndex{0}; passIndex < actuals_.size(); ++passIndex) {
-      if (const Symbol *
-          symbol{FindBoundOp(oprName, passIndex, *definedOpSymbolPtr)}) {
-        if (MaybeExpr result{TryBoundOp(*symbol, passIndex)}) {
-          return result;
+      const Symbol *generic{nullptr};
+      if (const Symbol *binding{
+              FindBoundOp(oprName, passIndex, generic, false)}) {
+        anyPossibilities = true;
+        if (MaybeExpr thisResult{TryBoundOp(*binding, passIndex)}) {
+          if (auto thisInaccessible{
+                  CheckAccessibleSymbol(scope, DEREF(generic))}) {
+            inaccessible = thisInaccessible;
+          } else {
+            result = std::move(thisResult);
+            hit.push_back(binding);
+          }
         }
       }
     }
   }
-  if (*definedOpSymbolPtr) {
-    SayNoMatch(ToUpperCase((*definedOpSymbolPtr)->name().ToString()));
-  } else if (actuals_.size() == 1 || AreConformable()) {
-    if (CheckForNullPointer()) {
-      context_.Say(error, ToUpperCase(opr), TypeAsFortran(0), TypeAsFortran(1));
+  if (result) {
+    if (hit.size() > 1) {
+      if (auto *msg{context_.Say(
+              "%zd matching accessible generic interfaces for %s were found"_err_en_US,
+              hit.size(), ToUpperCase(opr))}) {
+        for (const Symbol *symbol : hit) {
+          AttachDeclaration(*msg, *symbol);
+        }
+      }
     }
-  } else {
+  } else if (inaccessible) {
+    context_.Say(source_, std::move(*inaccessible));
+  } else if (anyPossibilities) {
+    SayNoMatch(ToUpperCase(oprNameString), false);
+  } else if (actuals_.size() == 2 && !AreConformable()) {
     context_.Say(
         "Operands of %s are not conformable; have rank %d and rank %d"_err_en_US,
         ToUpperCase(opr), actuals_[0]->Rank(), actuals_[1]->Rank());
+  } else if (CheckForNullPointer()) {
+    context_.Say(error, ToUpperCase(opr), TypeAsFortran(0), TypeAsFortran(1));
   }
-  return std::nullopt;
+  return result;
 }
 
 MaybeExpr ArgumentAnalyzer::TryDefinedOp(
     std::vector<const char *> oprs, parser::MessageFixedText error) {
-  const Symbol *definedOpSymbolPtr{nullptr};
-  for (std::size_t i{1}; i < oprs.size(); ++i) {
+  if (oprs.size() == 1) {
+    return TryDefinedOp(oprs[0], error);
+  }
+  MaybeExpr result;
+  std::vector<const char *> hit;
+  {
     auto restorer{context_.GetContextualMessages().DiscardMessages()};
-    if (auto result{TryDefinedOp(oprs[i], error, &definedOpSymbolPtr)}) {
-      return result;
+    for (std::size_t i{0}; i < oprs.size(); ++i) {
+      if (MaybeExpr thisResult{TryDefinedOp(oprs[i], error)}) {
+        result = std::move(thisResult);
+        hit.push_back(oprs[i]);
+      }
     }
   }
-  return TryDefinedOp(oprs[0], error, &definedOpSymbolPtr);
+  if (hit.empty()) { // for the error
+    result = TryDefinedOp(oprs[0], error);
+  } else if (hit.size() > 1) {
+    context_.Say(
+        "Matching accessible definitions were found with %zd variant spellings of the generic operator ('%s', '%s')"_err_en_US,
+        hit.size(), ToUpperCase(hit[0]), ToUpperCase(hit[1]));
+  }
+  return result;
 }
 
 MaybeExpr ArgumentAnalyzer::TryBoundOp(const Symbol &symbol, int passIndex) {

 }
 
 std::optional<ProcedureRef> ArgumentAnalyzer::GetDefinedAssignmentProc() {
-  auto restorer{context_.GetContextualMessages().DiscardMessages()};
+  const Symbol *proc{nullptr};
+  int passedObjectIndex{-1};
   std::string oprNameString{"assignment(=)"};
   parser::CharBlock oprName{oprNameString};
-  const Symbol *proc{nullptr};
   const auto &scope{context_.context().FindScope(source_)};
-  if (const Symbol * symbol{scope.FindSymbol(oprName)}) {
-    ExpressionAnalyzer::AdjustActuals noAdjustment;
-    auto pair{context_.ResolveGeneric(*symbol, actuals_, noAdjustment, true)};
-    if (pair.first) {
-      proc = pair.first;
-    } else {
-      context_.EmitGenericResolutionError(*symbol, pair.second);
-    }
-  }
-  int passedObjectIndex{-1};
-  const Symbol *definedOpSymbol{nullptr};
-  for (std::size_t i{0}; i < actuals_.size(); ++i) {
-    if (const Symbol * specific{FindBoundOp(oprName, i, definedOpSymbol)}) {
-      if (const Symbol *
-          resolution{GetBindingResolution(GetType(i), *specific)}) {
-        proc = resolution;
+  // If multiple resolutions were possible, they will have been already
+  // diagnosed.
+  {
+    auto restorer{context_.GetContextualMessages().DiscardMessages()};
+    if (const Symbol *symbol{scope.FindSymbol(oprName)}) {
+      ExpressionAnalyzer::AdjustActuals noAdjustment;
+      auto pair{context_.ResolveGeneric(*symbol, actuals_, noAdjustment, true)};
+      if (pair.first) {
+        proc = pair.first;
       } else {
-        proc = specific;
-        passedObjectIndex = i;
+        context_.EmitGenericResolutionError(*symbol, pair.second);
+      }
+    }
+    for (std::size_t i{0}; i < actuals_.size(); ++i) {
+      const Symbol *generic{nullptr};
+      if (const Symbol *specific{FindBoundOp(oprName, i, generic, true)}) {
+        if (const Symbol *resolution{
+                GetBindingResolution(GetType(i), *specific)}) {
+          proc = resolution;
+        } else {
+          proc = specific;
+          passedObjectIndex = i;
+        }
       }
     }
   }

 }
 
 // Look for a type-bound operator in the type of arg number passIndex.
-const Symbol *ArgumentAnalyzer::FindBoundOp(
-    parser::CharBlock oprName, int passIndex, const Symbol *&definedOp) {
+const Symbol *ArgumentAnalyzer::FindBoundOp(parser::CharBlock oprName,
+    int passIndex, const Symbol *&generic, bool isSubroutine) {
   const auto *type{GetDerivedTypeSpec(GetType(passIndex))};
   if (!type || !type->scope()) {
     return nullptr;
   }
-  const Symbol *symbol{type->scope()->FindComponent(oprName)};
-  if (!symbol) {
+  generic = type->scope()->FindComponent(oprName);
+  if (!generic) {
     return nullptr;
   }
-  definedOp = symbol;
   ExpressionAnalyzer::AdjustActuals adjustment{
       [&](const Symbol &proc, ActualArguments &) {
         return passIndex == GetPassIndex(proc);
       }};
-  auto pair{context_.ResolveGeneric(*symbol, actuals_, adjustment, false)};
+  auto pair{
+      context_.ResolveGeneric(*generic, actuals_, adjustment, isSubroutine)};
   if (!pair.first) {
-    context_.EmitGenericResolutionError(*symbol, pair.second);
+    context_.EmitGenericResolutionError(*generic, pair.second);
   }
   return pair.first;
 }

flang/lib/Semantics/resolve-names.cpp

       } else if (extends) {
         msg = "Type cannot be extended as it has a component named"
               " '%s'"_err_en_US;
-      } else if (CheckAccessibleComponent(currScope(), *prev)) {
+      } else if (CheckAccessibleSymbol(currScope(), *prev)) {
         // inaccessible component -- redeclaration is ok
         msg = "Component '%s' is inaccessibly declared in or as a "
               "parent of this derived type"_warn_en_US;

     derived->Instantiate(currScope()); // in case of forward referenced type
     if (const Scope * scope{derived->scope()}) {
       if (Resolve(component, scope->FindComponent(component.source))) {
-        if (auto msg{
-                CheckAccessibleComponent(currScope(), *component.symbol)}) {
+        if (auto msg{CheckAccessibleSymbol(currScope(), *component.symbol)}) {
           context().Say(component.source, *msg);
         }
         return &component;

flang/lib/Semantics/tools.cpp

   return IsAllocatable(symbol) && IsPolymorphic(symbol);
 }
 
-std::optional<parser::MessageFormattedText> CheckAccessibleComponent(
+std::optional<parser::MessageFormattedText> CheckAccessibleSymbol(
     const Scope &scope, const Symbol &symbol) {
-  CHECK(symbol.owner().IsDerivedType()); // symbol must be a component
   if (symbol.attrs().test(Attr::PRIVATE)) {
     if (FindModuleFileContaining(scope)) {
       // Don't enforce component accessibility checks in module files;

         moduleScope{FindModuleContaining(symbol.owner())}) {
       if (!moduleScope->Contains(scope)) {
         return parser::MessageFormattedText{
-            "PRIVATE component '%s' is only accessible within module '%s'"_err_en_US,
+            "PRIVATE name '%s' is only accessible within module '%s'"_err_en_US,
             symbol.name(), moduleScope->GetName().value()};
       }
     }

flang/test/Semantics/resolve34.f90

   type(t2) :: x
   integer :: j
   j = x%i2
-  !ERROR: PRIVATE component 'i3' is only accessible within module 'm7'
+  !ERROR: PRIVATE name 'i3' is only accessible within module 'm7'
   j = x%i3
-  !ERROR: PRIVATE component 't1' is only accessible within module 'm7'
+  !ERROR: PRIVATE name 't1' is only accessible within module 'm7'
   j = x%t1%i1
 end
 

 subroutine s8
   use m8
   type(t) :: x
-  !ERROR: PRIVATE component 'i2' is only accessible within module 'm8'
+  !ERROR: PRIVATE name 'i2' is only accessible within module 'm8'
   x = t(2, 5)
-  !ERROR: PRIVATE component 'i2' is only accessible within module 'm8'
+  !ERROR: PRIVATE name 'i2' is only accessible within module 'm8'
   x = t(i1=2, i2=5)
-  !ERROR: PRIVATE component 'i2' is only accessible within module 'm8'
+  !ERROR: PRIVATE name 'i2' is only accessible within module 'm8'
   a = [y%i2]
 end
 

     x = t(i1=2, i2=5)  !OK
   end
 end
+
+module m10
+  type t
+    integer n
+   contains
+    procedure :: f
+    generic, private :: operator(+) => f
+  end type
+ contains
+  type(t) function f(x,y)
+    class(t), intent(in) :: x, y
+    f = t(x%n + y%n)
+  end function
+end module
+subroutine s10
+  use m10
+  type(t) x
+  x = t(1)
+  !ERROR: PRIVATE name 'operator(+)' is only accessible within module 'm10'
+  x = x + x
+end subroutine

flang/test/Semantics/resolve63.f90

     l = z'fe' == r !OK
     l = cVar == z'fe' !OK
     l = z'fe' == cVar !OK
-    !ERROR: No intrinsic or user-defined OPERATOR(==) matches operand types CHARACTER(KIND=1) and INTEGER(4)
+    !ERROR: Operands of .EQ. must have comparable types; have CHARACTER(KIND=1) and INTEGER(4)
     l = charVar == z'fe'
-    !ERROR: No intrinsic or user-defined OPERATOR(==) matches operand types INTEGER(4) and CHARACTER(KIND=1)
+    !ERROR: Operands of .EQ. must have comparable types; have INTEGER(4) and CHARACTER(KIND=1)
     l = z'fe' == charVar
-    !ERROR: No intrinsic or user-defined OPERATOR(==) matches operand types LOGICAL(4) and INTEGER(4)
-    l = l == z'fe' !OK
-    !ERROR: No intrinsic or user-defined OPERATOR(==) matches operand types INTEGER(4) and LOGICAL(4)
-    l = z'fe' == l !OK
-    !ERROR: No intrinsic or user-defined OPERATOR(==) matches operand types TYPE(t) and REAL(4)
+    !ERROR: Operands of .EQ. must have comparable types; have LOGICAL(4) and INTEGER(4)
+    l = l == z'fe'
+    !ERROR: Operands of .EQ. must have comparable types; have INTEGER(4) and LOGICAL(4)
+    l = z'fe' == l
+    !ERROR: Operands of .EQ. must have comparable types; have TYPE(t) and REAL(4)
     l = x == r
 
     lVar = z'a' == b'1010' !OK

     i = x + y
     i = x + i
     i = y + i
-    !ERROR: No intrinsic or user-defined OPERATOR(+) matches operand types CLASS(t2) and CLASS(t1)
+    !ERROR: Operands of + must be numeric; have CLASS(t2) and CLASS(t1)
     i = y + x
-    !ERROR: No intrinsic or user-defined OPERATOR(+) matches operand types INTEGER(4) and CLASS(t1)
+    !ERROR: Operands of + must be numeric; have INTEGER(4) and CLASS(t1)
     i = i + x
   end
 end

     j = null() - null(mold=x1)
     j = null(mold=x1) - null()
     j = null() - null()
-    !ERROR: No intrinsic or user-defined OPERATOR(/) matches operand types untyped and TYPE(t1)
+    !ERROR: A NULL() pointer is not allowed as an operand here
     j = null() / null(mold=x1)
-    !ERROR: No intrinsic or user-defined OPERATOR(/) matches operand types TYPE(t1) and untyped
+    !ERROR: A NULL() pointer is not allowed as an operand here
     j = null(mold=x1) / null()
     !ERROR: A NULL() pointer is not allowed as an operand here
     j = null() / null()

flang/test/Semantics/resolve64.f90

   subroutine s1(x, y, z)
     logical :: x
     complex :: y, z
-    !ERROR: No intrinsic or user-defined OPERATOR(.A.) matches operand types COMPLEX(4) and COMPLEX(4)
+    !ERROR: Operands of .AND. must be LOGICAL; have COMPLEX(4) and COMPLEX(4)
     x = y .and. z
-    !ERROR: No intrinsic or user-defined OPERATOR(.A.) matches operand types COMPLEX(4) and COMPLEX(4)
+    !ERROR: Operands of .AND. must be LOGICAL; have COMPLEX(4) and COMPLEX(4)
     x = y .a. z
   end
 end