Revert "[flang] Detect circularly defined interfaces of procedures"

This reverts commit 93c5e6bb49.

This patch updates resolve102.f90 which is now failing in 6 out 8 of our
public buildbots:
  * http://lab.llvm.org:8011/#/builders/21/builds/9625
  * http://lab.llvm.org:8011/#/builders/134/builds/2395
  * http://lab.llvm.org:8011/#/builders/79/builds/6298
  * http://lab.llvm.org:8011/#/builders/66/builds/2084
  * http://lab.llvm.org:8011/#/builders/135/builds/2485
  * http://lab.llvm.org:8011/#/builders/32/builds/3551

Please see the following revisions for more context:
  * https://reviews.llvm.org/D97201
  * https://reviews.llvm.org/D97749

flang/include/flang/Semantics/semantics.h

@@ -199,7 +199,7 @@ private:
     IndexVarKind kind;
   };
   std::map<SymbolRef, const IndexVarInfo> activeIndexVars_;
-  SymbolSet errorSymbols_;
+  std::set<SymbolRef> errorSymbols_;
   std::set<std::string> tempNames_;
 };
 

flang/include/flang/Semantics/symbol.h

@@ -15,10 +15,9 @@
 #include "flang/Common/reference.h"
 #include "llvm/ADT/DenseMapInfo.h"
 #include <array>
-#include <functional>
 #include <list>
 #include <optional>
-#include <unordered_set>
+#include <set>
 #include <vector>
 
 namespace llvm {
@@ -596,7 +595,7 @@ public:
   bool operator==(const Symbol &that) const { return this == &that; }
   bool operator!=(const Symbol &that) const { return !(*this == that); }
   bool operator<(const Symbol &that) const {
-    // For maps of symbols: collate them by source location
+    // For sets of symbols: collate them by source location
     return name_.begin() < that.name_.begin();
   }
 
@@ -766,13 +765,7 @@ inline bool operator<(SymbolRef x, SymbolRef y) { return *x < *y; }
 inline bool operator<(MutableSymbolRef x, MutableSymbolRef y) {
   return *x < *y;
 }
-struct SymbolHash {
-  std::size_t operator()(SymbolRef symRef) const {
-    std::hash<std::string> hasher;
-    return hasher(symRef->name().ToString());
-  }
-};
-using SymbolSet = std::unordered_set<SymbolRef, SymbolHash>;
+using SymbolSet = std::set<SymbolRef>;
 
 } // namespace Fortran::semantics
 

flang/lib/Evaluate/characteristics.cpp

@@ -369,7 +369,7 @@ static std::optional<Procedure> CharacterizeProcedure(
     std::string procsList{GetSeenProcs(seenProcs)};
     context.messages().Say(symbol.name(),
         "Procedure '%s' is recursively defined.  Procedures in the cycle:"
-        " %s"_err_en_US,
+        " '%s'"_err_en_US,
         symbol.name(), procsList);
     return std::nullopt;
   }

flang/lib/Semantics/resolve-names.cpp

@@ -1003,7 +1003,6 @@ private:
     context().SetError(symbol);
     return symbol;
   }
-  bool HasCycle(const Symbol &, const ProcInterface &);
 };
 
 // Resolve construct entities and statement entities.
@@ -2133,7 +2132,7 @@ static bool NeedsType(const Symbol &symbol) {
 
 void ScopeHandler::ApplyImplicitRules(
     Symbol &symbol, bool allowForwardReference) {
-  if (context().HasError(symbol) || !NeedsType(symbol)) {
+  if (!NeedsType(symbol)) {
     return;
   }
   if (const DeclTypeSpec * type{GetImplicitType(symbol)}) {
@@ -3642,35 +3641,6 @@ Symbol &DeclarationVisitor::DeclareUnknownEntity(
   }
 }
 
-bool DeclarationVisitor::HasCycle(
-    const Symbol &procSymbol, const ProcInterface &interface) {
-  SymbolSet procsInCycle;
-  procsInCycle.insert(procSymbol);
-  const ProcInterface *thisInterface{&interface};
-  bool haveInterface{true};
-  while (haveInterface) {
-    haveInterface = false;
-    if (const Symbol * interfaceSymbol{thisInterface->symbol()}) {
-      if (procsInCycle.count(*interfaceSymbol) > 0) {
-        for (const auto procInCycle : procsInCycle) {
-          Say(procInCycle->name(),
-              "The interface for procedure '%s' is recursively "
-              "defined"_err_en_US,
-              procInCycle->name());
-          context().SetError(*procInCycle);
-        }
-        return true;
-      } else if (const auto *procDetails{
-                     interfaceSymbol->detailsIf<ProcEntityDetails>()}) {
-        haveInterface = true;
-        thisInterface = &procDetails->interface();
-        procsInCycle.insert(*interfaceSymbol);
-      }
-    }
-  }
-  return false;
-}
-
 Symbol &DeclarationVisitor::DeclareProcEntity(
     const parser::Name &name, Attrs attrs, const ProcInterface &interface) {
   Symbol &symbol{DeclareEntity<ProcEntityDetails>(name, attrs)};
@@ -3680,20 +3650,20 @@ Symbol &DeclarationVisitor::DeclareProcEntity(
           "The interface for procedure '%s' has already been "
           "declared"_err_en_US);
       context().SetError(symbol);
-    } else if (HasCycle(symbol, interface)) {
-      return symbol;
-    } else if (interface.type()) {
-      symbol.set(Symbol::Flag::Function);
-    } else if (interface.symbol()) {
-      if (interface.symbol()->test(Symbol::Flag::Function)) {
+    } else {
+      if (interface.type()) {
         symbol.set(Symbol::Flag::Function);
-      } else if (interface.symbol()->test(Symbol::Flag::Subroutine)) {
-        symbol.set(Symbol::Flag::Subroutine);
+      } else if (interface.symbol()) {
+        if (interface.symbol()->test(Symbol::Flag::Function)) {
+          symbol.set(Symbol::Flag::Function);
+        } else if (interface.symbol()->test(Symbol::Flag::Subroutine)) {
+          symbol.set(Symbol::Flag::Subroutine);
+        }
       }
+      details->set_interface(interface);
+      SetBindNameOn(symbol);
+      SetPassNameOn(symbol);
     }
-    details->set_interface(interface);
-    SetBindNameOn(symbol);
-    SetPassNameOn(symbol);
   }
   return symbol;
 }
@@ -5035,7 +5005,7 @@ Symbol *DeclarationVisitor::NoteInterfaceName(const parser::Name &name) {
 
 void DeclarationVisitor::CheckExplicitInterface(const parser::Name &name) {
   if (const Symbol * symbol{name.symbol}) {
-    if (!context().HasError(*symbol) && !symbol->HasExplicitInterface()) {
+    if (!symbol->HasExplicitInterface()) {
       Say(name,
           "'%s' must be an abstract interface or a procedure with "
           "an explicit interface"_err_en_US,

flang/test/Semantics/resolve102.f90

@@ -1,7 +1,7 @@
 ! RUN: %S/test_errors.sh %s %t %f18
 
 ! Tests for circularly defined procedures
-!ERROR: Procedure 'sub' is recursively defined.  Procedures in the cycle: 'p2', 'sub'
+!ERROR: Procedure 'sub' is recursively defined.  Procedures in the cycle: ''sub', 'p2''
 subroutine sub(p2)
   PROCEDURE(sub) :: p2
 
@@ -9,7 +9,7 @@ subroutine sub(p2)
 end subroutine
 
 subroutine circular
-  !ERROR: Procedure 'p' is recursively defined.  Procedures in the cycle: 'p2', 'p', 'sub'
+  !ERROR: Procedure 'p' is recursively defined.  Procedures in the cycle: ''p', 'sub', 'p2''
   procedure(sub) :: p
 
   call p(sub)
@@ -21,7 +21,7 @@ subroutine circular
 end subroutine circular
 
 program iface
-  !ERROR: Procedure 'p' is recursively defined.  Procedures in the cycle: 'p2', 'p', 'sub'
+  !ERROR: Procedure 'p' is recursively defined.  Procedures in the cycle: ''p', 'sub', 'p2''
   procedure(sub) :: p
   interface
     subroutine sub(p2)
@@ -38,7 +38,7 @@ Program mutual
   Call p(sub)
 
   contains
-    !ERROR: Procedure 'sub1' is recursively defined.  Procedures in the cycle: 'p', 'arg', 'sub1'
+    !ERROR: Procedure 'sub1' is recursively defined.  Procedures in the cycle: ''p', 'sub1', 'arg''
     Subroutine sub1(arg)
       procedure(sub1) :: arg
     End Subroutine
@@ -54,7 +54,7 @@ Program mutual1
   Call p(sub)
 
   contains
-    !ERROR: Procedure 'sub1' is recursively defined.  Procedures in the cycle: 'p2', 'sub', 'p', 'arg', 'sub1'
+    !ERROR: Procedure 'sub1' is recursively defined.  Procedures in the cycle: ''p', 'sub1', 'arg', 'sub', 'p2''
     Subroutine sub1(arg)
       procedure(sub) :: arg
     End Subroutine
@@ -63,24 +63,3 @@ Program mutual1
       Procedure(sub1) :: p2
     End Subroutine
 End Program
-
-program twoCycle
-  !ERROR: The interface for procedure 'p1' is recursively defined
-  !ERROR: The interface for procedure 'p2' is recursively defined
-  procedure(p1) p2
-  procedure(p2) p1
-  call p1
-  call p2
-end program
-
-program threeCycle
-  !ERROR: The interface for procedure 'p1' is recursively defined
-  !ERROR: The interface for procedure 'p2' is recursively defined
-  procedure(p1) p2
-  !ERROR: The interface for procedure 'p3' is recursively defined
-  procedure(p2) p3
-  procedure(p3) p1
-  call p1
-  call p2
-  call p3
-end program