[flang] Add more support for alternate returns

Add `hasAlternateReturns` to `evaluate::ProcedureRef`.

Add `HasAlternateReturns` to test subprogram symbols.

Fix `label01.F90` test: It was checking that "error: " didn't appear in
the output. But that was erroneously matching a warning that ends
"would be in error:". So change it to check for ": error: " instead.

Differential Revision: https://reviews.llvm.org/D83007

Author: tskeith

flang/include/flang/Evaluate/call.h

@@ -190,9 +190,10 @@ struct ProcedureDesignator {
 class ProcedureRef {
 public:
   CLASS_BOILERPLATE(ProcedureRef)
-  ProcedureRef(ProcedureDesignator &&p, ActualArguments &&a, bool alt = false)
-      : proc_{std::move(p)}, arguments_{std::move(a)}, hasAlternateReturns_{
-                                                           alt} {}
+  ProcedureRef(ProcedureDesignator &&p, ActualArguments &&a,
+      bool hasAlternateReturns = false)
+      : proc_{std::move(p)}, arguments_{std::move(a)},
+        hasAlternateReturns_{hasAlternateReturns} {}
   ~ProcedureRef();
 
   ProcedureDesignator &proc() { return proc_; }
@@ -203,7 +204,7 @@ class ProcedureRef {
   std::optional<Expr<SubscriptInteger>> LEN() const;
   int Rank() const;
   bool IsElemental() const { return proc_.IsElemental(); }
-  bool HasAlternateReturns() const { return hasAlternateReturns_; }
+  bool hasAlternateReturns() const { return hasAlternateReturns_; }
   bool operator==(const ProcedureRef &) const;
   llvm::raw_ostream &AsFortran(llvm::raw_ostream &) const;
 

flang/include/flang/Semantics/tools.h

@@ -100,7 +100,6 @@ bool IsInitialized(const Symbol &, bool ignoreDATAstatements = false);
 bool HasIntrinsicTypeName(const Symbol &);
 bool IsSeparateModuleProcedureInterface(const Symbol *);
 bool IsAutomatic(const Symbol &);
-// Given a subroutine symbol, tells if the subroutine has alternate returns
 bool HasAlternateReturns(const Symbol &);
 
 // Return an ultimate component of type that matches predicate, or nullptr.

flang/lib/Semantics/expression.cpp

@@ -2020,6 +2020,8 @@ void ExpressionAnalyzer::Analyze(const parser::CallStmt &callStmt) {
       ProcedureDesignator *proc{std::get_if<ProcedureDesignator>(&callee->u)};
       CHECK(proc);
       if (CheckCall(call.source, *proc, callee->arguments)) {
+        bool hasAlternateReturns{
+            analyzer.GetActuals().size() < actualArgList.size()};
         callStmt.typedCall.reset(new ProcedureRef{std::move(*proc),
             std::move(callee->arguments), hasAlternateReturns});
       }

flang/lib/Semantics/tools.cpp

@@ -1292,9 +1292,9 @@ void LabelEnforce::SayWithConstruct(SemanticsContext &context,
       .Attach(constructLocation, GetEnclosingConstructMsg());
 }
 
-bool HasAlternateReturns(const Symbol &sub) {
-  for (const auto *args : sub.get<SubprogramDetails>().dummyArgs()) {
-    if (!args) {
+bool HasAlternateReturns(const Symbol &subprogram) {
+  for (const auto *dummyArg : subprogram.get<SubprogramDetails>().dummyArgs()) {
+    if (!dummyArg) {
       return true;
     }
   }

flang/test/Semantics/label01.F90

@@ -1,13 +1,12 @@
 ! RUN: %f18 -funparse-with-symbols -DSTRICT_F18 -Mstandard %s 2>&1 | FileCheck %s
 ! RUN: %f18 -funparse-with-symbols -DARCHAIC_FORTRAN %s 2>&1 | FileCheck %s
-! CHECK-NOT: error:{{[[:space:]]}}
+! CHECK-NOT: :{{[[:space:]]}}error:{{[[:space:]]}}
 ! FIXME: the above check line does not work because diags are not emitted with error: in them.
 
 ! these are the conformance tests
 ! define STRICT_F18 to eliminate tests of features not in F18
 ! define ARCHAIC_FORTRAN to add test of feature found in Fortran before F95
 
-
 subroutine sub00(a,b,n,m)
   integer :: n, m
   real a(n)