Recognise and ignore Doxygen group commands @{ and @}

Fixes #1750

CHANGES.current

@@ -7,6 +7,9 @@ the issue number to the end of the URL: https://github.com/swig/swig/issues/
 Version 4.1.0 (in progress)
 ===========================
 
+2022-04-07: olly
+	    #1750 SWIG now recognises and ignores Doxygen group commands `@{` and `@}`.
+
 2022-04-06: wsfulton
             ./configure now enables C++11 and later C++ standards testing by default (when
             running: 'make check').

Examples/test-suite/doxygen_parsing.i

@@ -133,6 +133,15 @@ struct SomeAnotherStruct
 	}
 };
 
+struct Foo1750
+{
+  /// @name Group name
+  /// @{
+  int a;
+  /// @}
+  int b;
+};
+
 #ifdef SWIGPYTHON_BUILTIN
 bool is_python_builtin() { return true; }
 #else

Examples/test-suite/java/doxygen_parsing_runme.java

@@ -132,6 +132,14 @@ public class doxygen_parsing_runme {
     wantedComments.put("doxygen_parsing.doxygen_parsingConstants.CONSTANT_VALUE",
     		"The constant comment \n" +
     		"");
+    wantedComments.put("doxygen_parsing.Foo1750.getA()",
+	        "");
+    wantedComments.put("doxygen_parsing.Foo1750.getB()",
+	        "");
+    wantedComments.put("doxygen_parsing.Foo1750.setA(int)",
+	        "");
+    wantedComments.put("doxygen_parsing.Foo1750.setB(int)",
+	        "");
     
     // and ask the parser to check comments for us
     System.exit(CommentParser.check(wantedComments));

Source/Doxygen/doxycommands.h

@@ -44,6 +44,8 @@ const int sectionIndicatorsSize = sizeof(sectionIndicators) / sizeof(*sectionInd
 const char *simpleCommands[] = {
   // the first line are escaped chars, except \~, which is a language ID command.
   "n", "$", "@", "\\", "&", "~", "<", ">", "#", "%", "\"", ".", "::",
+  // Member groups, which we currently ignore.
+  "{", "}",
   "endcond",
   "callgraph", "callergraph", "showinitializer", "hideinitializer", "internal",
   "nosubgrouping", "public", "publicsection", "private", "privatesection",

Source/Doxygen/doxyparser.h

@@ -238,7 +238,7 @@ private:
    * Method for Adding a Simple Command
    * Format: @command
    * Plain commands, such as newline etc, they contain no other data
-   *  \n \\ \@ \& \$ \# \< \> \%
+   *  \n \\ \@ \& \$ \# \< \> \% \{ \}
    */
   void addSimpleCommand(const std::string &theCommand, DoxygenEntityList &doxyList);
   /*

Source/Modules/python.cxx

@@ -5053,8 +5053,11 @@ public:
       Printv(f_shadow, tab4, symname, variable_annotation, " = property(", module, ".", getname, NIL);
       if (assignable)
 	Printv(f_shadow, ", ", module, ".", setname, NIL);
-      if (have_docstring(n))
+      if (have_docstring(n)) {
-	Printv(f_shadow, ", doc=", docstring(n, AUTODOC_VAR, tab4), NIL);
+	String *s = docstring(n, AUTODOC_VAR, tab4);
+	if (Len(s))
+	  Printv(f_shadow, ", doc=", s, NIL);
+      }
       Printv(f_shadow, ")\n", NIL);
       Delete(variable_annotation);
       Delete(mname);
@@ -5121,8 +5124,11 @@ public:
 	  Printv(f_shadow, tab4, symname, " = property(", module, ".", getname, NIL);
 	  if (assignable)
 	    Printv(f_shadow, ", ", module, ".", setname, NIL);
-	  if (have_docstring(n))
+	  if (have_docstring(n)) {
-	    Printv(f_shadow, ", doc=", docstring(n, AUTODOC_VAR, tab4), NIL);
+	    String *s = docstring(n, AUTODOC_VAR, tab4);
+	    if (Len(s))
+	      Printv(f_shadow, ", doc=", s, NIL);
+	  }
 	  Printv(f_shadow, ")\n", NIL);
 	}
 	String *getter = Getattr(n, "pybuiltin:getter");