[Macros] Attributes on MacroExpansionDecl

* Parse `#<identifier>` attribute list as a `MacroExpansionDecl`
  regardless of the position
* Diagnose whitespaces between `#` and the macro name.
* Correctly attach attributes to `MacroExpansionDecl`
* Reject modifiers and 'static' on `MacroExpansionDecl` for now
* Copy attributes on `MacroExpansionDecl` to expanded Decls
* Fix `OrigDeclAttributes` to handle modifiers (use `getLocation()`
  instead of `AtLoc`.)

rdar://107386648

Author: rintaro

include/swift/Parse/Parser.h

@@ -905,6 +905,9 @@ class Parser {
   /// Returns true if the parser is at the start of a SIL decl.
   bool isStartOfSILDecl();
 
+  /// Returns true if the parser is at a freestanding macro expansion.
+  bool isStartOfFreestandingMacroExpansion();
+
   /// Parse the top-level Swift items into the provided vector.
   ///
   /// Each item will be a declaration, statement, or expression.

lib/AST/Attr.cpp

@@ -855,7 +855,7 @@ OrigDeclAttrFilter::operator()(const DeclAttribute *Attr) const {
   auto declLoc = decl->getStartLoc();
   auto *mod = decl->getModuleContext();
   auto *declFile = mod->getSourceFileContainingLocation(declLoc);
-  auto *attrFile = mod->getSourceFileContainingLocation(Attr->AtLoc);
+  auto *attrFile = mod->getSourceFileContainingLocation(Attr->getLocation());
   if (!declFile || !attrFile)
     return Attr;
 

lib/Parse/ParseDecl.cpp

@@ -4828,13 +4828,21 @@ bool Parser::isStartOfSwiftDecl(bool allowPoundIfAttributes) {
         (Tok.is(tok::pound_endif) && !allowPoundIfAttributes))
       return true;
 
+    // Force parsing '#<identifier>' after attributes as a macro expansion decl.
+    if (isStartOfFreestandingMacroExpansion())
+      return true;
+
     return isStartOfSwiftDecl(allowPoundIfAttributes);
   }
 
-  if (Tok.is(tok::pound) && peekToken().is(tok::identifier)) {
-    // Macro expansions at the top level are declarations.
-    return !isInSILMode() && SF.Kind != SourceFileKind::Interface &&
-        CurDeclContext->isModuleScopeContext() && !allowTopLevelCode();
+  if (Tok.is(tok::pound)) {
+    if (isStartOfFreestandingMacroExpansion()) {
+      // Macro expansions at the top level of non-script file are declarations.
+      return CurDeclContext->isModuleScopeContext() && !allowTopLevelCode();
+    }
+
+    // Otherwise, prefer parsing it as an expression.
+    return false;
   }
 
   // Skip a #if that contains only attributes in all branches. These will be
@@ -4997,6 +5005,21 @@ bool Parser::isStartOfSILDecl() {
   llvm_unreachable("Unhandled case in switch");
 }
 
+bool Parser::isStartOfFreestandingMacroExpansion() {
+  // Check if "'#' <identifier>" without any whitespace between them.
+  if (!Tok.is(tok::pound))
+    return false;
+  if (Tok.getLoc().getAdvancedLoc(1) != peekToken().getLoc())
+    return false;
+  if (!peekToken().isAny(tok::identifier, tok::code_complete) &&
+      // allow keywords right after '#' so we can diagnose it when parsing.
+      !peekToken().isKeyword())
+    return false;
+  if (isInSILMode() || SF.Kind == SourceFileKind::Interface)
+    return false;
+  return true;
+}
+
 void Parser::consumeDecl(ParserPosition BeginParserPosition,
                          ParseDeclOptions Flags,
                          bool IsTopLevel) {
@@ -5249,9 +5272,15 @@ Parser::parseDecl(ParseDeclOptions Flags,
     // Handled below.
     break;
   case tok::pound:
-    if (Tok.isAtStartOfLine() &&
-        peekToken().is(tok::code_complete) &&
-        Tok.getLoc().getAdvancedLoc(1) == peekToken().getLoc()) {
+    if (!isStartOfFreestandingMacroExpansion()) {
+      consumeToken(tok::pound);
+      diagnose(Tok.getLoc(),
+               diag::macro_expansion_decl_expected_macro_identifier);
+      DeclResult = makeParserError();
+      break;
+    }
+
+    if (peekToken().is(tok::code_complete)) {
       consumeToken();
       if (CodeCompletionCallbacks) {
         CodeCompletionCallbacks->completeAfterPoundDirective();
@@ -9796,10 +9825,10 @@ Parser::parseDeclMacroExpansion(ParseDeclOptions flags,
     }
   }
 
-  return makeParserResult(
-      status,
-      new (Context) MacroExpansionDecl(
-        CurDeclContext, poundLoc, macroNameRef, macroNameLoc,
-        leftAngleLoc, Context.AllocateCopy(genericArgs), rightAngleLoc,
-        argList));
+  auto *med = new (Context) MacroExpansionDecl(
+      CurDeclContext, poundLoc, macroNameRef, macroNameLoc, leftAngleLoc,
+      Context.AllocateCopy(genericArgs), rightAngleLoc, argList);
+  med->getAttrs() = attributes;
+
+  return makeParserResult(status, med);
 }

lib/Parse/ParseExpr.cpp

@@ -1841,6 +1841,12 @@ ParserResult<Expr> Parser::parseExprPrimary(Diag<> ID, bool isExprBasic) {
   }
 
   case tok::pound:
+    if (!isStartOfFreestandingMacroExpansion()) {
+      consumeToken(tok::pound);
+      diagnose(Tok.getLoc(),
+               diag::macro_expansion_expr_expected_macro_identifier);
+      return makeParserError();
+    }
     if (peekToken().is(tok::code_complete) &&
         Tok.getLoc().getAdvancedLoc(1) == peekToken().getLoc()) {
       return parseExprPoundCodeCompletion(/*ParentKind*/None);

lib/Sema/TypeCheckDeclPrimary.cpp

@@ -2058,6 +2058,15 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
   }
 
   void visitMacroExpansionDecl(MacroExpansionDecl *MED) {
+    // Attributes will be attached to expanded decls and type checked later.
+    // Don't perform "type check attribute" here.
+
+    // Decline decl modifiers. I.e. we don't support 'public #funcFoo'.
+    for (auto *attr : MED->getAttrs()) {
+      if (attr->isValid() && attr->isDeclModifier()) {
+        diagnoseAndRemoveAttr(MED, attr, diag::invalid_decl_modifier, attr);
+      }
+    }
     // Assign a discriminator.
     (void)MED->getDiscriminator();
     // Decls in expansion already visited as auxiliary decls.

lib/Sema/TypeCheckMacros.cpp

@@ -1049,8 +1049,10 @@ swift::expandFreestandingMacro(MacroExpansionDecl *med) {
 
   auto topLevelItems = macroSourceFile->getTopLevelItems();
   for (auto item : topLevelItems) {
-    if (auto *decl = item.dyn_cast<Decl *>())
+    if (auto *decl = item.dyn_cast<Decl *>()) {
+      decl->getAttrs().add(med->getAttrs());
       decl->setDeclContext(dc);
+    }
   }
   return macroBufferID;
 }
@@ -1549,6 +1551,9 @@ ConcreteDeclRef ResolveMacroRequest::evaluate(Evaluator &evaluator,
       macroRef.getArgs(), roles);
   }
 
+  // FIXME: Type checking should reflect the attributes on the expansion.
+  // e.g. '@available(macOS 999) #Future { newAPIFrom999() }'.
+
   Expr *result = macroExpansion;
   TypeChecker::typeCheckExpression(
       result, dc, {}, TypeCheckExprFlags::DisableMacroExpansions);

test/Parse/line-directive.swift

@@ -30,8 +30,8 @@ public struct S {
 // expected-error@+5{{operators must have one or two arguments}}
 // expected-error@+4{{member operator '/()' must have at least one argument of type 'S'}}
 // expected-error@+3{{expected '{' in body of function declaration}}
-// expected-error@+2 2 {{consecutive declarations on a line must be separated by ';}}
-// expected-error@+1 2 {{expected a macro identifier}}
+// expected-error@+2 {{consecutive declarations on a line must be separated by ';}}
+// expected-error@+1 {{expected a macro identifier}}
 / ###line 25 "line-directive.swift"
 }
 // expected-error@+1{{#line directive was renamed to #sourceLocation}}

test/Parse/object_literals.swift

@@ -4,5 +4,4 @@ let _ = #notAPound // expected-error {{no macro named 'notAPound'}}
 let _ = #notAPound(1, 2) // expected-error {{no macro named 'notAPound'}}
 let _ = #Color // expected-error {{no macro named 'Color'}}
 
-let _ = [##] // expected-error 2 {{expected a macro identifier}} {{none}}
-// expected-error @-1 {{consecutive statements on a line must be separated by ';'}}
+let _ = [##] // expected-error {{expected a macro identifier}} {{none}}

test/Parse/raw_string_errors.swift

@@ -12,15 +12,15 @@ let _ = #"\##("invalid")"#
 let _ = ###"""invalid"######
 // expected-error@-1{{too many '#' characters in closing delimiter}}{{26-29=}}
 // expected-error@-2{{consecutive statements on a line must be separated by ';'}}
-// expected-error@-3 3 {{expected a macro identifier}}
+// expected-error@-3{{expected a macro identifier}}
 
 let _ = ####"invalid"###
 // expected-error@-1{{unterminated string literal}}
 
 let _ = ###"invalid"######
 // expected-error@-1{{too many '#' characters in closing delimiter}}{{24-27=}}
 // expected-error@-2{{consecutive statements on a line must be separated by ';'}}
-// expected-error@-3 3 {{expected a macro identifier}}
+// expected-error@-3{{expected a macro identifier}}
 
 let _ = ##"""aa
   foobar

test/StringProcessing/Frontend/disable-flag.swift

@@ -9,6 +9,6 @@ _ = /x/
 // expected-error@-2 {{cannot find 'x' in scope}}
 // expected-error@-3 {{'/' is not a postfix unary operator}}
 
-_ = #/x/# // expected-error 2 {{expected a macro identifier}}
+_ = #/x/# // expected-error {{expected a macro identifier}}
 
 func foo(_ x: Regex<Substring>) {} // expected-error {{cannot find type 'Regex' in scope}}