Detect when the string "<::" is found in code after a cast or template name
and is interpreted as "[:" because of the digraph "<:". When found, give an
error with a fix-it to add whitespace between the "<" and "::". Also,
repair the token stream and recover parsing afterwards.
Index: test/Parser/cxx-casting.cpp
===================================================================
--- test/Parser/cxx-casting.cpp (revision 128572)
+++ test/Parser/cxx-casting.cpp (working copy)
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -fsyntax-only %s
+// RUN: %clang_cc1 -fsyntax-only -verify %s
char *const_cast_test(const char *var)
{
@@ -37,3 +37,12 @@
template <class T> class A {};
void foo() { A<int>(*(A<int>*)0); }
}
+
+typedef char* c;
+typedef A* a;
+void test2(char x, struct B * b) {
+ (void)const_cast<::c>(&x); // expected-error{{found '<::' after a const_cast which forms the digraph '<:' (aka '[') and a ':', did you mean '< ::'?}}
+ (void)dynamic_cast<::a>(b); // expected-error{{found '<::' after a dynamic_cast which forms the digraph '<:' (aka '[') and a ':', did you mean '< ::'?}}
+ (void)reinterpret_cast<::c>(x); // expected-error{{found '<::' after a reinterpret_cast which forms the digraph '<:' (aka '[') and a ':', did you mean '< ::'?}}
+ (void)static_cast<::c>(&x); // expected-error{{found '<::' after a static_cast which forms the digraph '<:' (aka '[') and a ':', did you mean '< ::'?}}
+}
Index: test/SemaTemplate/temp_arg_template.cpp
===================================================================
--- test/SemaTemplate/temp_arg_template.cpp (revision 128572)
+++ test/SemaTemplate/temp_arg_template.cpp (working copy)
@@ -30,9 +30,8 @@
A<f> *a9; // expected-error{{must be a class template}}
-// FIXME: The code below is ill-formed, because of the evil digraph '<:'.
-// We should provide a much better error message than we currently do.
-// A<::N::Z> *a10;
+// Evil digraph '<:' is parsed as '[', expect error.
+A<::N::Z> *a10; // expected-error{{found '<::' after a template name which forms the digraph '<:' (aka '[') and a ':', did you mean '< ::'?}}
// PR7807
namespace N {
Index: include/clang/Basic/DiagnosticParseKinds.td
===================================================================
--- include/clang/Basic/DiagnosticParseKinds.td (revision 128572)
+++ include/clang/Basic/DiagnosticParseKinds.td (working copy)
@@ -410,6 +410,10 @@
// C++ declarations
def err_friend_decl_defines_class : Error<
"cannot define a type in a friend declaration">;
+def err_missing_whitespace_digraph : Error<
+ "found '<::' after a "
+ "%select{template name|const_cast|dynamic_cast|reinterpret_cast|static_cast}0"
+ " which forms the digraph '<:' (aka '[') and a ':', did you mean '< ::'?">;
def warn_deleted_function_accepted_as_extension: ExtWarn<
"deleted function definition accepted as a C++0x extension">, InGroup<CXX0x>;
Index: lib/Parse/ParseExprCXX.cpp
===================================================================
--- lib/Parse/ParseExprCXX.cpp (revision 128572)
+++ lib/Parse/ParseExprCXX.cpp (working copy)
@@ -20,6 +20,45 @@
using namespace clang;
+static int SelectDigraphErrorMessage(tok::TokenKind Kind) {
+ switch (Kind) {
+ case tok::kw_template: return 0;
+ case tok::kw_const_cast: return 1;
+ case tok::kw_dynamic_cast: return 2;
+ case tok::kw_reinterpret_cast: return 3;
+ case tok::kw_static_cast: return 4;
+ default:
+ assert(0 && "Unknown type for digraph error message.");
+ return -1;
+ }
+}
+
+// Suggest fixit for "<::" after a cast.
+static void FixDigraph(Parser &P, Preprocessor &PP, Token &DigraphToken,
+ Token &ColonToken, tok::TokenKind Kind, bool AtDigraph) {
+ // Pull '<:' and ':' off token stream.
+ if (!AtDigraph)
+ PP.Lex(DigraphToken);
+ PP.Lex(ColonToken);
+
+ SourceRange Range;
+ Range.setBegin(DigraphToken.getLocation());
+ Range.setEnd(ColonToken.getLocation());
+ P.Diag(DigraphToken.getLocation(), diag::err_missing_whitespace_digraph)
+ << SelectDigraphErrorMessage(Kind)
+ << FixItHint::CreateReplacement(Range, "< ::");
+
+ // Reuse tokens to preserve source location and macro instantiation
+ // information.
+ ColonToken.setKind(tok::coloncolon);
+ DigraphToken.setKind(tok::less);
+
+ // Push new tokens back to token stream.
+ PP.EnterToken(ColonToken);
+ if (!AtDigraph)
+ PP.EnterToken(DigraphToken);
+}
+
/// \brief Parse global scope or nested-name-specifier if present.
///
/// Parses a C++ global scope specifier ('::') or nested-name-specifier (which
@@ -287,6 +326,28 @@
continue;
}
+ // Check for '<::' which should be '< ::' instead of '[:' when following
+ // a template name.
+ if (Next.is(tok::l_square) && Next.getLength() == 2) {
+ Token SecondToken = GetLookAheadToken(2);
+ if (SecondToken.is(tok::colon)) {
+ TemplateTy Template;
+ UnqualifiedId TemplateName;
+ TemplateName.setIdentifier(&II, Tok.getLocation());
+ bool MemberOfUnknownSpecialization;
+ if (Actions.isTemplateName(getCurScope(), SS,
+ /*hasTemplateKeyword=*/false,
+ TemplateName,
+ ObjectType,
+ EnteringContext,
+ Template,
+ MemberOfUnknownSpecialization)) {
+ FixDigraph(*this, PP, Next, SecondToken, tok::kw_template,
+ /*AtDigraph*/false);
+ }
+ }
+ }
+
// nested-name-specifier:
// type-name '<'
if (Next.is(tok::less)) {
@@ -453,6 +514,13 @@
SourceLocation OpLoc = ConsumeToken();
SourceLocation LAngleBracketLoc = Tok.getLocation();
+ // Check for "<::" which is parsed as "[:". If found, fix token stream,
+ // diagnose error, suggest fix, and recover parsing.
+ Token Next = NextToken();
+ if (Tok.is(tok::l_square) && Tok.getLength() == 2 && Next.is(tok::colon)) {
+ FixDigraph(*this, PP, Tok, Next, Kind, /*AtDigraph*/true);
+ }
+
if (ExpectAndConsume(tok::less, diag::err_expected_less_after, CastName))
return ExprError();
_______________________________________________
cfe-commits mailing list
[email protected]
http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
