[flang] add isModuleFile flag to parser::Options, use it

Original-commit: flang-compiler/f18@0727140f53
Reviewed-on: https://github.com/flang-compiler/f18/pull/151
Tree-same-pre-rewrite: false

flang/lib/parser/parsing.cc

@@ -78,8 +78,8 @@ void Parsing::Prescan(const std::string &path, Options options) {
     prescanner.AddCompilerDirectiveSentinel("$omp");
     prescanner.AddCompilerDirectiveSentinel("$");  // OMP conditional line
   }
-  ProvenanceRange range{
-      allSources.AddIncludedFile(*sourceFile, ProvenanceRange{})};
+  ProvenanceRange range{allSources.AddIncludedFile(
+      *sourceFile, ProvenanceRange{}, options.isModuleFile)};
   prescanner.Prescan(range);
   cooked_.Marshal();
 }

flang/lib/parser/parsing.h

@@ -42,6 +42,7 @@ struct Options {
   std::vector<std::string> searchDirectories;
   std::vector<Predefinition> predefinitions;
   bool instrumentedParse{false};
+  bool isModuleFile{false};
 };
 
 class Parsing {

flang/lib/semantics/mod-file.cc

@@ -355,7 +355,9 @@ bool ModFileReader::Read(const SourceName &modName) {
   }
   // TODO: Construct parsing with an AllSources reference to share provenance
   parser::Parsing parsing;
-  parsing.Prescan(*path, {});
+  parser::Options options;
+  options.isModuleFile = true;
+  parsing.Prescan(*path, options);
   parsing.Parse(&std::cout);
   auto &parseTree{parsing.parseTree()};
   if (!parsing.messages().empty() || !parsing.consumedWholeFile() ||
@@ -372,6 +374,7 @@ bool ModFileReader::Read(const SourceName &modName) {
     return false;
   }
   auto &modSymbol{*it->second};
+  // TODO: Preserve the CookedSource rather than a copy of its string.
   modSymbol.scope()->set_chars(std::string{parsing.cooked().data()});
   modSymbol.set(Symbol::Flag::ModFile);
   return true;