From: Aaron Ballman <aaron@aaronballman.com>
Date: Tue, 14 Feb 2017 22:47:20 +0000 (+0000)
Subject: Improve diagnostic reporting when using __declspec without enabling __declspec as... 
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=8e4aad78974956d3cc99409a2567494117611b47;p=clang

Improve diagnostic reporting when using __declspec without enabling __declspec as a keyword.

Fixes PR31936.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@295114 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/include/clang/Basic/DiagnosticParseKinds.td b/include/clang/Basic/DiagnosticParseKinds.td
index 19b95cd5bd..2f34bf1fac 100644
--- a/include/clang/Basic/DiagnosticParseKinds.td
+++ b/include/clang/Basic/DiagnosticParseKinds.td
@@ -176,6 +176,9 @@ def warn_gcc_attribute_location : Warning<
 def warn_attribute_no_decl : Warning<
   "attribute %0 ignored, because it is not attached to a declaration">, 
   InGroup<IgnoredAttributes>;
+def err_ms_attributes_not_enabled : Error<
+  "'__declspec' attributes are not enabled; use '-fdeclspec' or "
+  "'-fms-extensions' to enable support for __declspec attributes">;
 def err_expected_method_body : Error<"expected method body">;
 def err_declspec_after_virtspec : Error<
   "'%0' qualifier may not appear after the virtual specifier '%1'">;
diff --git a/lib/Parse/ParseDecl.cpp b/lib/Parse/ParseDecl.cpp
index 7ffafe2dab..e0347ccf2f 100644
--- a/lib/Parse/ParseDecl.cpp
+++ b/lib/Parse/ParseDecl.cpp
@@ -2966,6 +2966,31 @@ void Parser::ParseDeclarationSpecifiers(DeclSpec &DS,
       if (DS.hasTypeSpecifier())
         goto DoneWithDeclSpec;
 
+      // If the token is an identifier named "__declspec" and Microsoft
+      // extensions are not enabled, it is likely that there will be cascading
+      // parse errors if this really is a __declspec attribute. Attempt to
+      // recognize that scenario and recover gracefully.
+      if (!getLangOpts().DeclSpecKeyword && Tok.is(tok::identifier) &&
+          Tok.getIdentifierInfo()->getName().equals("__declspec")) {
+        Diag(Loc, diag::err_ms_attributes_not_enabled);
+
+        // The next token should be an open paren. If it is, eat the entire
+        // attribute declaration and continue.
+        if (NextToken().is(tok::l_paren)) {
+          // Consume the __declspec identifier.
+          SourceLocation Loc = ConsumeToken();
+
+          // Eat the parens and everything between them.
+          BalancedDelimiterTracker T(*this, tok::l_paren);
+          if (T.consumeOpen()) {
+            assert(false && "Not a left paren?");
+            return;
+          }
+          T.skipToEnd();
+          continue;
+        }
+      }
+
       // In C++, check to see if this is a scope specifier like foo::bar::, if
       // so handle it as such.  This is important for ctor parsing.
       if (getLangOpts().CPlusPlus) {
diff --git a/test/Parser/declspec-recovery.c b/test/Parser/declspec-recovery.c
new file mode 100644
index 0000000000..b256861b9f
--- /dev/null
+++ b/test/Parser/declspec-recovery.c
@@ -0,0 +1,8 @@
+// RUN: %clang_cc1 -triple i386-pc-unknown -fsyntax-only -verify %s
+
+__declspec(naked) void f(void) {} // expected-error{{'__declspec' attributes are not enabled; use '-fdeclspec' or '-fms-extensions' to enable support for __declspec attributes}}
+
+struct S {
+  __declspec(property(get=Getter, put=Setter)) int X; // expected-error{{'__declspec' attributes are not enabled; use '-fdeclspec' or '-fms-extensions' to enable support for __declspec attributes}}
+  int Y;
+};
diff --git a/test/Parser/declspec-supported.c b/test/Parser/declspec-supported.c
new file mode 100644
index 0000000000..f9004893a4
--- /dev/null
+++ b/test/Parser/declspec-supported.c
@@ -0,0 +1,10 @@
+// RUN: %clang_cc1 -triple i386-pc-unknown -fsyntax-only -fms-extensions -verify %s
+// RUN: %clang_cc1 -triple i386-pc-unknown -fsyntax-only -fdeclspec -verify %s
+// expected-no-diagnostics
+
+__declspec(naked) void f(void) {}
+
+struct S {
+  __declspec(property(get=Getter, put=Setter)) int X;
+  int Y;
+};