Tidy up and improve error recovery for C++11 attributes in bad places. Based on

a patch by Michael Han.

llvm-svn: 192666

3 files changed, 65 insertions, 18 deletions

diff --git a/clang/lib/Parse/ParseDeclCXX.cpp b/clang/lib/Parse/ParseDeclCXX.cpp
index 6594749592a..21b24bfd79e 100644
--- a/clang/lib/Parse/ParseDeclCXX.cpp
+++ b/clang/lib/Parse/ParseDeclCXX.cpp
@@ -453,13 +453,11 @@ Decl *Parser::ParseUsingDeclaration(unsigned Context,
   CXXScopeSpec SS;
   SourceLocation TypenameLoc;
   bool HasTypenameKeyword = false;
-  ParsedAttributesWithRange Attrs(AttrFactory);
 
-  // FIXME: Simply skip the attributes and diagnose, don't bother parsing them.
-  MaybeParseCXX11Attributes(Attrs);
-  ProhibitAttributes(Attrs);
-  Attrs.clear();
-  Attrs.Range = SourceRange();
+  // Check for misplaced attributes before the identifier in an
+  // alias-declaration.
+  ParsedAttributesWithRange MisplacedAttrs(AttrFactory);
+  MaybeParseCXX11Attributes(MisplacedAttrs);
 
   // Ignore optional 'typename'.
   // FIXME: This is wrong; we should parse this as a typename-specifier.
@@ -509,12 +507,24 @@ Decl *Parser::ParseUsingDeclaration(unsigned Context,
     return 0;
   }
 
+  ParsedAttributesWithRange Attrs(AttrFactory);
   MaybeParseCXX11Attributes(Attrs);
 
   // Maybe this is an alias-declaration.
-  bool IsAliasDecl = Tok.is(tok::equal);
   TypeResult TypeAlias;
+  bool IsAliasDecl = Tok.is(tok::equal);
   if (IsAliasDecl) {
+    // If we had any misplaced attributes from earlier, this is where they
+    // should have been written.
+    if (MisplacedAttrs.Range.isValid()) {
+      Diag(MisplacedAttrs.Range.getBegin(), diag::err_attributes_not_allowed)
+        << FixItHint::CreateInsertionFromRange(
+               Tok.getLocation(),
+               CharSourceRange::getTokenRange(MisplacedAttrs.Range))
+        << FixItHint::CreateRemoval(MisplacedAttrs.Range);
+      Attrs.takeAllFrom(MisplacedAttrs);
+    }
+
     // TODO: Can GNU attributes appear here?
     ConsumeToken();
 
@@ -565,6 +575,7 @@ Decl *Parser::ParseUsingDeclaration(unsigned Context,
   } else {
     // C++11 attributes are not allowed on a using-declaration, but GNU ones
     // are.
+    ProhibitAttributes(MisplacedAttrs);
     ProhibitAttributes(Attrs);
 
     // Parse (optional) attributes (most likely GNU strong-using extension).
@@ -3282,6 +3293,37 @@ void Parser::ParseCXX11Attributes(ParsedAttributesWithRange &attrs,
   attrs.Range = SourceRange(StartLoc, *endLoc);
 }
 
+void Parser::DiagnoseAndSkipCXX11Attributes() {
+  if (!isCXX11AttributeSpecifier())
+    return;
+
+  // Start and end location of an attribute or an attribute list.
+  SourceLocation StartLoc = Tok.getLocation();
+  SourceLocation EndLoc;
+
+  do {
+    if (Tok.is(tok::l_square)) {
+      BalancedDelimiterTracker T(*this, tok::l_square);
+      T.consumeOpen();
+      T.skipToEnd();
+      EndLoc = T.getCloseLocation();
+    } else {
+      assert(Tok.is(tok::kw_alignas) && "not an attribute specifier");
+      ConsumeToken();
+      BalancedDelimiterTracker T(*this, tok::l_paren);
+      if (!T.consumeOpen())
+        T.skipToEnd();
+      EndLoc = T.getCloseLocation();
+    }
+  } while (isCXX11AttributeSpecifier());
+
+  if (EndLoc.isValid()) {
+    SourceRange Range(StartLoc, EndLoc);
+    Diag(StartLoc, diag::err_attributes_not_allowed)
+      << Range;
+  }
+}
+
 /// ParseMicrosoftAttributes - Parse a Microsoft attribute [Attr]
 ///
 /// [MS] ms-attribute:
diff --git a/clang/lib/Parse/ParseStmt.cpp b/clang/lib/Parse/ParseStmt.cpp
index ef1ab89b8c9..f57ff97ceb5 100644
--- a/clang/lib/Parse/ParseStmt.cpp
+++ b/clang/lib/Parse/ParseStmt.cpp
@@ -1314,14 +1314,12 @@ StmtResult Parser::ParseDoStatement() {
     return StmtError();
   }
 
-  // Parse the parenthesized condition.
+  // Parse the parenthesized expression.
   BalancedDelimiterTracker T(*this, tok::l_paren);
   T.consumeOpen();
 
-  // FIXME: Do not just parse the attribute contents and throw them away
-  ParsedAttributesWithRange attrs(AttrFactory);
-  MaybeParseCXX11Attributes(attrs);
-  ProhibitAttributes(attrs);
+  // A do-while expression is not a condition, so can't have attributes.
+  DiagnoseAndSkipCXX11Attributes();
 
   ExprResult Cond = ParseExpression();
   T.consumeClose();
@@ -2547,9 +2545,10 @@ StmtResult Parser::ParseCXXTryBlockCommon(SourceLocation TryLoc, bool FnTry) {
   }
   else {
     StmtVector Handlers;
-    ParsedAttributesWithRange attrs(AttrFactory);
-    MaybeParseCXX11Attributes(attrs);
-    ProhibitAttributes(attrs);
+
+    // C++11 attributes can't appear here, despite this context seeming
+    // statement-like.
+    DiagnoseAndSkipCXX11Attributes();
 
     if (Tok.isNot(tok::kw_catch))
       return StmtError(Diag(Tok, diag::err_expected_catch));
diff --git a/clang/lib/Parse/Parser.cpp b/clang/lib/Parse/Parser.cpp
index 378a239744f..f0a3d9190c3 100644
--- a/clang/lib/Parse/Parser.cpp
+++ b/clang/lib/Parse/Parser.cpp
@@ -1958,12 +1958,18 @@ bool BalancedDelimiterTracker::diagnoseMissingClose() {
   }
   P.Diag(P.Tok, DID);
   P.Diag(LOpen, diag::note_matching) << LHSName;
-  if (P.SkipUntil(Close, FinalToken, /*StopAtSemi*/ true, /*DontConsume*/ true)
-      && P.Tok.is(Close))
+
+  // If we're not already at some kind of closing bracket, skip to our closing
+  // token.
+  if (P.Tok.isNot(tok::r_paren) && P.Tok.isNot(tok::r_brace) &&
+      P.Tok.isNot(tok::r_square) &&
+      P.SkipUntil(Close, FinalToken, /*StopAtSemi*/true, /*DontConsume*/true) &&
+      P.Tok.is(Close))
     LClose = P.ConsumeAnyToken();
   return true;
 }
 
 void BalancedDelimiterTracker::skipToEnd() {
-  P.SkipUntil(Close, false);
+  P.SkipUntil(Close, false, true);
+  consumeClose();
 }