[C++11] Allow static_assert at the top level

And disallow it right after template<T>).

Fixes https://github.com/swig/swig/issues/1031 reported by Artem V L.

CHANGES.current

@@ -7,6 +7,11 @@ the issue number to the end of the URL: https://github.com/swig/swig/issues/
 Version 4.0.0 (in progress)
 ===========================
 
+2017-08-05: olly
+	    [C++11] Allow static_assert at the top level (and disallow it right
+	    after template<T>).  Fixes https://github.com/swig/swig/issues/1031
+	    reported by Artem V L.
+
 2017-07-17: fflexo
             [Java] #674 Add std_list.i to add support for std::list containers. The Java proxy
             extends java.util.AbstractSequentialList and makes the C++ std::list container look

Doc/Manual/CPlusPlus11.html

@@ -877,7 +877,8 @@ so in this case it is entirely possible to pass an int instead of a double to <t
 
 
 <p>
-SWIG correctly parses the new <tt>static_assert</tt> declarations.
+SWIG correctly parses the new <tt>static_assert</tt> declarations (though 3.0.12 and earlier
+had a bug which meant this wasn't accepted at file scope).
 This is a C++ compile time directive so there isn't anything useful that SWIG can do with it.
 </p>
 

Examples/test-suite/cpp11_static_assert.i

@@ -1,12 +1,22 @@
-/* This test case checks whether SWIG correctly parses and ignores the
+/* This test case checks whether SWIG correctly parses and ignores
-   keywords "static_assert()" inside the class or struct.
+   "static_assert()" in various places.
 */
 %module cpp11_static_assert
 
 %inline %{
+static_assert(sizeof(int) >= 2, "What?  int size is invalid!");
+
+namespace dummy {
+// C++17 allows the message to be omitted, so check that works too.
+static_assert(sizeof(int) >= sizeof(short));
+}
+
 template <typename T>
 struct Check1 {
   static_assert(sizeof(int) <= sizeof(T), "not big enough");
+  Check1() {
+      static_assert(true);
+  }
 };
 
 template <typename T>

Source/CParse/parser.y

@@ -2991,6 +2991,9 @@ c_declaration   : c_decl {
 		  SetFlag($$,"aliastemplate");
 		  add_symbols($$);
 		}
+                | cpp_static_assert {
+                   $$ = $1;
+                }
                 ;
 
 /* ------------------------------------------------------------
@@ -4209,9 +4212,6 @@ cpp_temp_possible:  c_decl {
                 | cpp_constructor_decl {
                    $$ = $1;
                 }
-                | cpp_static_assert {
-                   $$ = $1;
-                }
                 | cpp_template_decl {
 		  $$ = 0;
                 }
@@ -4469,7 +4469,6 @@ cpp_member   : c_declaration { $$ = $1; }
                  default_arguments($$);
              }
              | cpp_destructor_decl { $$ = $1; }
-             | cpp_static_assert { $$ = $1; }
              | cpp_protection_decl { $$ = $1; }
              | cpp_swig_directive { $$ = $1; }
              | cpp_conversion_operator { $$ = $1; }
@@ -4673,7 +4672,8 @@ cpp_catch_decl : CATCH LPAREN parms RPAREN LBRACE {
                }
                ;
 
-/* static_assert(bool, const char*); */
+/* static_assert(bool, const char*); (C++11)
+ * static_assert(bool); (C++17) */
 cpp_static_assert : STATIC_ASSERT LPAREN {
                 skip_balanced('(',')');
                 $$ = 0;