Introduce a new data structure to explicitly model scopes in the AST

include/swift/AST/DiagnosticsFrontend.def

@@ -91,6 +91,11 @@ ERROR(error_immediate_mode_primary_file,none,
   "immediate mode is incompatible with -primary-file", ())
 ERROR(error_missing_frontend_action,none,
   "no frontend action was selected", ())
+ERROR(error_invalid_source_location_str,none,
+  "invalid source location string '%0'", (StringRef))
+ERROR(error_no_source_location_scope_map,none,
+  "-dump-scope-maps argument must be 'expanded' or a list of source locations",
+  ())
 
 ERROR(error_mode_cannot_emit_dependencies,none,
   "this mode does not support emitting dependency files", ())

include/swift/AST/Module.h

@@ -44,6 +44,7 @@ namespace clang {
 namespace swift {
   enum class ArtificialMainKind : uint8_t;
   class ASTContext;
+  class ASTScope;
   class ASTWalker;
   class BraceStmt;
   class Decl;
@@ -818,6 +819,9 @@ class SourceFile final : public FileUnit {
   /// source file.
   llvm::SetVector<NormalProtocolConformance *> UsedConformances;
 
+  /// The scope map that describes this source file.
+  ASTScope *Scope = nullptr;
+
   friend ASTContext;
   friend Impl;
 
@@ -968,6 +972,9 @@ class SourceFile final : public FileUnit {
   /// Otherwise, return an empty string.
   StringRef getFilename() const;
 
+  /// Retrieve the scope that describes this source file.
+  ASTScope &getScope();
+
   void dump() const;
   void dump(raw_ostream &os) const;
 

include/swift/Frontend/FrontendOptions.h

@@ -142,6 +142,9 @@ class FrontendOptions {
     DumpAST, ///< Parse, type-check, and dump AST
     PrintAST, ///< Parse, type-check, and pretty-print AST
 
+    /// Parse and dump scope map.
+    DumpScopeMaps,
+
     /// Parse, type-check, and dump type refinement context hierarchy
     DumpTypeRefinementContexts,
 
@@ -251,6 +254,10 @@ class FrontendOptions {
   /// Indicates a debug crash mode for the frontend.
   DebugCrashMode CrashMode = DebugCrashMode::None;
 
+  /// Line and column for each of the locations to be probed by
+  /// -dump-scope-maps.
+  SmallVector<std::pair<unsigned, unsigned>, 2> DumpScopeMapLocations;
+
   /// Indicates whether the RequestedAction has output.
   bool actionHasOutput() const;
 

include/swift/Option/Options.td

@@ -423,6 +423,11 @@ def dump_parse : Flag<["-"], "dump-parse">,
 def dump_ast : Flag<["-"], "dump-ast">,
   HelpText<"Parse and type-check input file(s) and dump AST(s)">, ModeOpt,
   Flags<[FrontendOption, NoInteractiveOption, DoesNotAffectIncrementalBuild]>;
+def dump_scope_maps : Separate<["-"], "dump-scope-maps">,
+  HelpText<"Parse and type-check input file(s) and dump the scope map(s)">,
+  MetaVarName<"<expanded-or-list-of-line:column>">,
+  ModeOpt,
+  Flags<[FrontendOption, NoInteractiveOption, DoesNotAffectIncrementalBuild]>;
 def dump_type_refinement_contexts :
   Flag<["-"], "dump-type-refinement-contexts">,
   HelpText<"Type-check input file(s) and dump type refinement contexts(s)">,