[ASTScope] Add APIs for determining whether a given source location is inside

a macro argument.

(cherry picked from commit cd79cf9)

Author: hborla

include/swift/AST/ASTScope.h

@@ -278,6 +278,17 @@ class ASTScopeImpl : public ASTAllocated<ASTScopeImpl> {
   static std::pair<CaseStmt *, CaseStmt *>
   lookupFallthroughSourceAndDest(SourceFile *sourceFile, SourceLoc loc);
 
+  /// Returns \c true if the given source location is inside an attached
+  /// or freestanding macro argument.
+  static bool isInMacroArgument(SourceFile *sourceFile, SourceLoc loc);
+
+  /// Returns \c true if this scope contains macro arguments.
+  ///
+  /// This is always true within macro expansion decl scopes, and it's
+  /// true within custom attribute scopes if the attribute name is a
+  /// potential macro reference.
+  virtual bool isMacroArgumentScope() const { return false; }
+
   /// Scopes that cannot bind variables may set this to true to create more
   /// compact scope tree in the debug info.
   virtual bool ignoreInDebugInfo() const { return false; }
@@ -867,7 +878,15 @@ class CustomAttributeScope final : public ASTScopeImpl {
   NullablePtr<DeclAttribute> getDeclAttributeIfAny() const override {
     return attr;
   }
- bool ignoreInDebugInfo() const override { return true; }
+  bool ignoreInDebugInfo() const override { return true; }
+
+  bool isMacroArgumentScope() const override {
+    // FIXME: This should check whether the attribute name is
+    // a macro. Otherwise, macro expansion will be suppressed
+    // for property wrapper arguments.
+    return true;
+  }
+  
 private:
   void expandAScopeThatDoesNotCreateANewInsertionPoint(ScopeCreator &);
 };
@@ -1266,6 +1285,10 @@ class MacroExpansionDeclScope final : public ASTScopeImpl {
   SourceRange
   getSourceRangeOfThisASTNode(bool omitAssertions = false) const override;
 
+  bool isMacroArgumentScope() const override {
+    return true;
+  }
+
 protected:
   void printSpecifics(llvm::raw_ostream &out) const override;
 

include/swift/AST/NameLookup.h

@@ -815,6 +815,10 @@ class ASTScope : public ASTAllocated<ASTScope> {
   static std::pair<CaseStmt *, CaseStmt *>
   lookupFallthroughSourceAndDest(SourceFile *sourceFile, SourceLoc loc);
 
+  /// Returns \c true if the given source location is inside an attached
+  /// or freestanding macro argument.
+  static bool isInMacroArgument(SourceFile *sourceFile, SourceLoc loc);
+
   SWIFT_DEBUG_DUMP;
   void print(llvm::raw_ostream &) const;
   void dumpOneScopeMapLocation(std::pair<unsigned, unsigned>);

lib/AST/ASTScope.cpp

@@ -60,6 +60,11 @@ std::pair<CaseStmt *, CaseStmt *> ASTScope::lookupFallthroughSourceAndDest(
   return ASTScopeImpl::lookupFallthroughSourceAndDest(sourceFile, loc);
 }
 
+bool ASTScope::isInMacroArgument(SourceFile *sourceFile,
+                                 SourceLoc loc) {
+  return ASTScopeImpl::isInMacroArgument(sourceFile, loc);
+}
+
 #if SWIFT_COMPILER_IS_MSVC
 #pragma warning(push)
 #pragma warning(disable : 4996)

lib/AST/ASTScopeLookup.cpp

@@ -675,3 +675,21 @@ std::pair<CaseStmt *, CaseStmt *> ASTScopeImpl::lookupFallthroughSourceAndDest(
 
   return { nullptr, nullptr };
 }
+
+bool ASTScopeImpl::isInMacroArgument(SourceFile *sourceFile,
+                                     SourceLoc loc) {
+  if (!sourceFile || sourceFile->Kind == SourceFileKind::Interface)
+    return false;
+
+  if (loc.isInvalid())
+    return false;
+
+  auto *fileScope = sourceFile->getScope().impl;
+  auto *scope = fileScope->findInnermostEnclosingScope(loc, nullptr);
+  do {
+    if (scope->isMacroArgumentScope())
+      return true;
+  } while ((scope = scope->getParent().getPtrOrNull()));
+
+  return false;
+}