[flang] Accept more unrecognized !DIR$ compiler directives

flang/include/flang/Parser/dump-parse-tree.h

@@ -207,6 +207,7 @@ class ParseTreeDumper {
   NODE(CompilerDirective, LoopCount)
   NODE(CompilerDirective, AssumeAligned)
   NODE(CompilerDirective, NameValue)
+  NODE(CompilerDirective, Unrecognized)
   NODE(parser, ComplexLiteralConstant)
   NODE(parser, ComplexPart)
   NODE(parser, ComponentArraySpec)

flang/include/flang/Parser/parse-tree-visitor.h

@@ -861,6 +861,18 @@ template <typename M> void Walk(CompilerDirective &x, M &mutator) {
   }
 }
 template <typename V>
+void Walk(const CompilerDirective::Unrecognized &x, V &visitor) {
+  if (visitor.Pre(x)) {
+    visitor.Post(x);
+  }
+}
+template <typename M>
+void Walk(CompilerDirective::Unrecognized &x, M &mutator) {
+  if (mutator.Pre(x)) {
+    mutator.Post(x);
+  }
+}
+template <typename V>
 void Walk(const OmpLinearClause::WithModifier &x, V &visitor) {
   if (visitor.Pre(x)) {
     Walk(x.modifier, visitor);

flang/include/flang/Parser/parse-tree.h

@@ -3298,7 +3298,8 @@ struct StmtFunctionStmt {
 // Compiler directives
 // !DIR$ IGNORE_TKR [ [(tkrdmac...)] name ]...
 // !DIR$ LOOP COUNT (n1[, n2]...)
-// !DIR$ name...
+// !DIR$ name[=value] [, name[=value]]...    = can be :
+// !DIR$ <anything else>
 struct CompilerDirective {
   UNION_CLASS_BOILERPLATE(CompilerDirective);
   struct IgnoreTKR {
@@ -3316,9 +3317,10 @@ struct CompilerDirective {
     TUPLE_CLASS_BOILERPLATE(NameValue);
     std::tuple<Name, std::optional<std::uint64_t>> t;
   };
+  struct Unrecognized {};
   CharBlock source;
   std::variant<std::list<IgnoreTKR>, LoopCount, std::list<AssumeAligned>,
-      std::list<NameValue>>
+      std::list<NameValue>, Unrecognized>
       u;
 };
 

flang/lib/Parser/Fortran-parsers.cpp

@@ -1261,24 +1261,28 @@ TYPE_PARSER(construct<StatOrErrmsg>("STAT =" >> statVariable) ||
 // Directives, extensions, and deprecated statements
 // !DIR$ IGNORE_TKR [ [(tkrdmac...)] name ]...
 // !DIR$ LOOP COUNT (n1[, n2]...)
-// !DIR$ name...
+// !DIR$ name[=value] [, name[=value]]...
+// !DIR$ <anything else>
 constexpr auto ignore_tkr{
-    "DIR$ IGNORE_TKR" >> optionalList(construct<CompilerDirective::IgnoreTKR>(
-                             maybe(parenthesized(many(letter))), name))};
+    "IGNORE_TKR" >> optionalList(construct<CompilerDirective::IgnoreTKR>(
+                        maybe(parenthesized(many(letter))), name))};
 constexpr auto loopCount{
-    "DIR$ LOOP COUNT" >> construct<CompilerDirective::LoopCount>(
-                             parenthesized(nonemptyList(digitString64)))};
-constexpr auto assumeAligned{"DIR$ ASSUME_ALIGNED" >>
+    "LOOP COUNT" >> construct<CompilerDirective::LoopCount>(
+                        parenthesized(nonemptyList(digitString64)))};
+constexpr auto assumeAligned{"ASSUME_ALIGNED" >>
     optionalList(construct<CompilerDirective::AssumeAligned>(
         indirect(designator), ":"_tok >> digitString64))};
-TYPE_PARSER(beginDirective >>
-    sourced(construct<CompilerDirective>(ignore_tkr) ||
-        construct<CompilerDirective>(loopCount) ||
-        construct<CompilerDirective>(assumeAligned) ||
+TYPE_PARSER(beginDirective >> "DIR$ "_tok >>
+    sourced((construct<CompilerDirective>(ignore_tkr) ||
+                construct<CompilerDirective>(loopCount) ||
+                construct<CompilerDirective>(assumeAligned) ||
+                construct<CompilerDirective>(
+                    many(construct<CompilerDirective::NameValue>(
+                        name, maybe(("="_tok || ":"_tok) >> digitString64))))) /
+            endOfStmt ||
         construct<CompilerDirective>(
-            "DIR$" >> many(construct<CompilerDirective::NameValue>(name,
-                          maybe(("="_tok || ":"_tok) >> digitString64))))) /
-        endOfStmt)
+            SkipTo<'\n'>{} >> pure<CompilerDirective::Unrecognized>()) /
+            endOfStmt))
 
 TYPE_PARSER(extension<LanguageFeature::CrayPointer>(
     "nonstandard usage: based POINTER"_port_en_US,

flang/lib/Parser/unparse.cpp

@@ -1827,6 +1827,10 @@ class UnparseVisitor {
             [&](const std::list<CompilerDirective::NameValue> &names) {
               Walk("!DIR$ ", names, " ");
             },
+            [&](const CompilerDirective::Unrecognized &) {
+              Word("!DIR$ ");
+              Word(x.source.ToString());
+            },
         },
         x.u);
     Put('\n');

flang/test/Parser/unrecognized-dir.f90

@@ -0,0 +1,4 @@
+! RUN: %flang_fc1 -fsyntax-only %s 2>&1 | FileCheck %s
+!CHECK: warning: Compiler directive was ignored
+!DIR$ Not a recognized directive
+end