Remove FindLocalVal

Replace with an ASTScope lookup. This also lets
us simplify UsableFilteringDeclConsumer, and fixes
a couple of completion bugs.

Author: hamishknight

include/swift/AST/NameLookup.h

@@ -442,8 +442,8 @@ class AccessFilteringDeclConsumer final : public VisibleDeclConsumer {
                  DynamicLookupInfo dynamicLookupInfo = {}) override;
 };
 
-/// Filters out decls that are not usable based on their source location, eg.
-/// a decl inside its own initializer or a non-type decl before its definition.
+/// Filters out decls that are not usable based on their source location, e.g.
+/// a top-level decl inside its own initializer or shadowed decls.
 class UsableFilteringDeclConsumer final : public VisibleDeclConsumer {
   const SourceManager &SM;
   const DeclContext *DC;
@@ -465,7 +465,7 @@ class UsableFilteringDeclConsumer final : public VisibleDeclConsumer {
   }
 
   void foundDecl(ValueDecl *D, DeclVisibilityKind reason,
-                 DynamicLookupInfo dynamicLookupInfo) override;
+                 DynamicLookupInfo dynamicLookupInfo = {}) override;
 };
 
 /// Remove any declarations in the given set that were overridden by
@@ -504,14 +504,11 @@ bool removeShadowedDecls(TinyPtrVector<OperatorDecl *> &decls,
 bool removeShadowedDecls(TinyPtrVector<PrecedenceGroupDecl *> &decls,
                          const DeclContext *dc);
 
-/// Finds decls visible in the given context and feeds them to the given
-/// VisibleDeclConsumer.  If the current DeclContext is nested in a function,
-/// the SourceLoc is used to determine which declarations in that function
-/// are visible.
-void lookupVisibleDecls(VisibleDeclConsumer &Consumer,
-                        const DeclContext *DC,
-                        bool IncludeTopLevel,
-                        SourceLoc Loc = SourceLoc());
+/// Finds decls visible in the given context at the given location and feeds
+/// them to the given VisibleDeclConsumer. The \p Loc must be valid, and \p DC
+/// must be in a SourceFile.
+void lookupVisibleDecls(VisibleDeclConsumer &Consumer, SourceLoc Loc,
+                        const DeclContext *DC, bool IncludeTopLevel);
 
 /// Finds decls visible as members of the given type and feeds them to the given
 /// VisibleDeclConsumer.
@@ -630,70 +627,6 @@ SelfBounds getSelfBoundsFromGenericSignature(const ExtensionDecl *extDecl);
 
 namespace namelookup {
 
-/// Searches through statements and patterns for local variable declarations.
-class FindLocalVal : public StmtVisitor<FindLocalVal> {
-  friend class ASTVisitor<FindLocalVal>;
-
-  const SourceManager &SM;
-  SourceLoc Loc;
-  VisibleDeclConsumer &Consumer;
-
-public:
-  FindLocalVal(const SourceManager &SM, SourceLoc Loc,
-               VisibleDeclConsumer &Consumer)
-      : SM(SM), Loc(Loc), Consumer(Consumer) {}
-
-  void checkValueDecl(ValueDecl *D, DeclVisibilityKind Reason);
-
-  void checkPattern(const Pattern *Pat, DeclVisibilityKind Reason);
-  
-  void checkParameterList(const ParameterList *params);
-
-  void checkGenericParams(GenericParamList *Params);
-
-  void checkSourceFile(const SourceFile &SF);
-
-private:
-  bool isReferencePointInRange(SourceRange R) {
-    return SM.rangeContainsTokenLoc(R, Loc);
-  }
-
-  void visitBreakStmt(BreakStmt *) {}
-  void visitContinueStmt(ContinueStmt *) {}
-  void visitFallthroughStmt(FallthroughStmt *) {}
-  void visitFailStmt(FailStmt *) {}
-  void visitReturnStmt(ReturnStmt *) {}
-  void visitYieldStmt(YieldStmt *) {}
-  void visitThenStmt(ThenStmt *) {}
-  void visitThrowStmt(ThrowStmt *) {}
-  void visitDiscardStmt(DiscardStmt *) {}
-  void visitPoundAssertStmt(PoundAssertStmt *) {}
-  void visitDeferStmt(DeferStmt *DS) {
-    // Nothing in the defer is visible.
-  }
-
-  void checkStmtCondition(const StmtCondition &Cond);
-
-  void visitIfStmt(IfStmt *S);
-  void visitGuardStmt(GuardStmt *S);
-
-  void visitWhileStmt(WhileStmt *S);
-  void visitRepeatWhileStmt(RepeatWhileStmt *S);
-  void visitDoStmt(DoStmt *S);
-
-  void visitForEachStmt(ForEachStmt *S);
-
-  void visitBraceStmt(BraceStmt *S, bool isTopLevelCode = false);
-  
-  void visitSwitchStmt(SwitchStmt *S);
-
-  void visitCaseStmt(CaseStmt *S);
-
-  void visitDoCatchStmt(DoCatchStmt *S);
-  
-};
-
-
 /// The bridge between the legacy UnqualifiedLookupFactory and the new ASTScope
 /// lookup system
 class AbstractASTScopeDeclConsumer {
@@ -737,9 +670,9 @@ class AbstractASTScopeDeclConsumer {
   }
 
 #ifndef NDEBUG
-  virtual void startingNextLookupStep() = 0;
-  virtual void finishingLookup(std::string) const = 0;
-  virtual bool isTargetLookup() const = 0;
+  virtual void startingNextLookupStep() {}
+  virtual void finishingLookup(std::string) const {}
+  virtual bool isTargetLookup() const { return false; }
 #endif
 };