Remove -py3 command line option

Closes #1779

CHANGES.current

@@ -7,6 +7,14 @@ the issue number to the end of the URL: https://github.com/swig/swig/issues/
 Version 4.1.0 (in progress)
 ===========================
 
+2022-03-23: wsfulton
+            [Python] #1779 The -py3 option is deprecated and now has no effect on the
+            code generated. Use of this option results in a deprecated warning.
+            The related SWIGPYTHON_PY3 macro that this option defined is no longer generated.
+
+            Note that %pythonnondynamic feature generates a metaclass that works on both
+            Python 2 and Python 3.
+
 2022-03-21: wsfulton
             [Python] #1779 pyabc.i for abstract base classes now supports versions of
             Python prior to 3.3 by using the collection module for these older versions.

Doc/Manual/Preprocessor.html

@@ -169,7 +169,6 @@ SWIG_D_VERSION                  Unsigned integer target version when using D
 SWIGGO_CGO                      Defined when using Go for cgo
 SWIGGO_GCCGO                    Defined when using Go for gccgo
 SWIGGO_INTGO_SIZE               Size of the Go type int when using Go (32 or 64)
-SWIGPYTHON_PY3                  Defined when using Python with -py3
 SWIGPYTHON_BUILTIN              Defined when using Python with -builtin
 SWIG_RUBY_AUTORENAME            Defined when using Ruby with -autorename
 </pre></div>

Doc/Manual/Python.html

@@ -152,11 +152,6 @@
 <!-- INDEX -->
 
 
-
-<p>
-<b>Caution: This chapter is under repair!</b>
-</p>
-
 <p>
 This chapter describes SWIG's support of Python.  SWIG is compatible
 with all recent Python versions (Python 2.7 and Python &gt;= 3.2).  If you
@@ -967,7 +962,6 @@ swig -python -help
 <tr><td>-nortti         </td><td>Disable the use of the native C++ RTTI with directors</td></tr>
 <tr><td>-nothreads      </td><td>Disable thread support for the entire interface</td></tr>
 <tr><td>-olddefs        </td><td>Keep the old method definitions when using -fastproxy</td></tr>
-<tr><td>-py3            </td><td>Generate code with Python 3 specific features and syntax</td></tr>
 <tr><td>-relativeimport </td><td>Use relative Python imports</td></tr>
 <tr><td>-threads        </td><td>Add thread support for all the interface</td></tr>
 <tr><td>-O              </td><td>Enable the following optimization options: -fastdispatch -fastproxy -fvirtual</td></tr>
@@ -6744,13 +6738,11 @@ to do this (remember you are now the Python importer) or use dynamic linking.
 
 <p>
 SWIG is able to support Python 3.x. The wrapper code generated by
-SWIG can be compiled with both Python 2.x or 3.x. Further more, by
+SWIG can be compiled with both Python 2.x or 3.x.
-passing the <tt>-py3</tt> command line option to SWIG, wrapper code
+</p>
-with some Python 3 specific features can be generated (see below
-subsections for details of these features).
 
 <p>
-There is a list of known-to-be-broken features in Python 3:
+The list of known-to-be-broken features around Python 3 are:
 </p>
 <ul>
   <li>No more support for FILE* typemaps, because PyFile_AsFile has been dropped
@@ -6875,7 +6867,7 @@ class V(object):
 
 <p>
 <b>Compatibility Note:</b> SWIG-4.1.0 changed the way that function annotations are generated.
-Prior versions required the <tt>-py3</tt> option to generate function annotation support
+Prior versions required the (now removed) <tt>-py3</tt> option to generate function annotation support
 containing C/C++ types instead of supporting <tt>%feature("python:annotations", "c")</tt>.
 Variable annotations were also added in SWIG-4.1.0.
 </p>

Examples/Makefile.in

@@ -329,13 +329,6 @@ else
 endif
 PYTHON_SO     = @PYTHON_SO@
 
-# SWIG option for Python3
-ifneq (,$(PY2))
-  SWIGOPTPY3 =
-else
-  SWIGOPTPY3 = -py3
-endif
-
 PYCODESTYLE       = @PYCODESTYLE@
 PYCODESTYLE_FLAGS = --ignore=E252,E30,E402,E501,E731,W291,W391
 
@@ -344,7 +337,7 @@ PYCODESTYLE_FLAGS = --ignore=E252,E30,E402,E501,E731,W291,W391
 # ----------------------------------------------------------------
 
 python: $(SRCDIR_SRCS)
-	$(SWIG) -python $(SWIGOPTPY3) $(SWIGOPT) -o $(ISRCS) $(INTERFACEPATH)
+	$(SWIG) -python $(SWIGOPT) -o $(ISRCS) $(INTERFACEPATH)
 	$(CC) -c $(CCSHARED) $(CPPFLAGS) $(CFLAGS) $(ISRCS) $(SRCDIR_SRCS) $(INCLUDES) $(PYTHON_INCLUDE)
 	$(LDSHARED) $(CFLAGS) $(LDFLAGS) $(OBJS) $(IOBJS) $(PYTHON_DLNK) $(LIBS) -o $(LIBPREFIX)_$(TARGET)$(PYTHON_SO)
 
@@ -353,7 +346,7 @@ python: $(SRCDIR_SRCS)
 # -----------------------------------------------------------------
 
 python_cpp: $(SRCDIR_SRCS)
-	$(SWIG) -python $(SWIGOPTPY3) -c++ $(SWIGOPT) -o $(ICXXSRCS) $(INTERFACEPATH)
+	$(SWIG) -python -c++ $(SWIGOPT) -o $(ICXXSRCS) $(INTERFACEPATH)
 	$(CXX) -c $(CCSHARED) $(CPPFLAGS) $(CXXFLAGS) $(ICXXSRCS) $(SRCDIR_SRCS) $(SRCDIR_CXXSRCS) $(INCLUDES) $(PYTHON_INCLUDE)
 	$(CXXSHARED) $(CXXFLAGS) $(LDFLAGS) $(OBJS) $(IOBJS) $(PYTHON_DLNK) $(LIBS) $(CPP_DLLIBS) -o $(LIBPREFIX)_$(TARGET)$(PYTHON_SO)
 
@@ -369,12 +362,12 @@ TKINTER =
 PYTHON_LIBOPTS = $(PYTHON_LINK) @LIBS@ $(TKINTER) $(SYSLIBS)
 
 python_static: $(SRCDIR_SRCS)
-	$(SWIG) -python $(SWIGOPTPY3) -lembed.i $(SWIGOPT) -o $(ISRCS) $(INTERFACEPATH)
+	$(SWIG) -python -lembed.i $(SWIGOPT) -o $(ISRCS) $(INTERFACEPATH)
 	$(CC) $(CPPFLAGS) $(CFLAGS) $(LDFLAGS) @LINKFORSHARED@ $(ISRCS) $(SRCDIR_SRCS) $(INCLUDES) \
 	$(PYTHON_INCLUDE) $(LIBS) -L$(PYTHON_LIB) $(PYTHON_LIBOPTS) -o $(TARGET)
 
 python_static_cpp: $(SRCDIR_SRCS)
-	$(SWIG) -python $(SWIGOPTPY3) -c++ -lembed.i $(SWIGOPT) -o $(ICXXSRCS) $(INTERFACEPATH)
+	$(SWIG) -python -c++ -lembed.i $(SWIGOPT) -o $(ICXXSRCS) $(INTERFACEPATH)
 	$(CXX) $(CPPFLAGS) $(CXXFLAGS) $(LDFLAGS) $(ICXXSRCS) $(SRCDIR_SRCS) $(SRCDIR_CXXSRCS) $(INCLUDES) \
 	$(PYTHON_INCLUDE) $(LIBS)  -L$(PYTHON_LIB) $(PYTHON_LIBOPTS) -o $(TARGET)
 

Examples/test-suite/python_annotations_c.i

@@ -1,7 +1,7 @@
 %module python_annotations_c
 
 // Tests the C/C++ annotations that were automatically added by using -py3 before swig-4.1.0
-// In swig-4.1.0 and later, the feature below is needed as annotations are no longer generated with -py3
+// In swig-4.1.0 and later, the feature below is needed as the -py3 option was dropped
 %feature("python:annotations", "c") mymethod;
 %feature("python:annotations", "c") makeT<short>;
 %feature("python:annotations", "c") global_ints;

Source/Modules/python.cxx

@@ -69,8 +69,6 @@ static int no_header_file = 0;
 static int max_bases = 0;
 static int builtin_bases_needed = 0;
 
-static int py3 = 0;
-
 /* C++ Support + Shadow Classes */
 
 static int have_constructor = 0;
@@ -131,7 +129,6 @@ static const char *usage3 = "\
      -nortti         - Disable the use of the native C++ RTTI with directors\n\
      -nothreads      - Disable thread support for the entire interface\n\
      -olddefs        - Keep the old method definitions when using -fastproxy\n\
-     -py3            - Generate code with Python 3 specific features and syntax\n\
      -relativeimport - Use relative Python imports\n\
      -threads        - Add thread support for all the interface\n\
      -O              - Enable the following optimization options:\n\
@@ -396,10 +393,6 @@ public:
 	  fputs(usage1, stdout);
 	  fputs(usage2, stdout);
 	  fputs(usage3, stdout);
-	} else if (strcmp(argv[i], "-py3") == 0) {
-	  py3 = 1;
-	  Preprocessor_define("SWIGPYTHON_PY3", 0);
-	  Swig_mark_arg(i);
 	} else if (strcmp(argv[i], "-builtin") == 0) {
 	  builtin = 1;
 	  Preprocessor_define("SWIGPYTHON_BUILTIN", 0);
@@ -415,7 +408,10 @@ public:
 		   strcmp(argv[i], "-modernargs") == 0 ||
 		   strcmp(argv[i], "-noproxydel") == 0 ||
 		   strcmp(argv[i], "-safecstrings") == 0) {
-	  Printf(stderr, "Deprecated command line option: %s. This option is now always on.\n", argv[i]);
+	  Printf(stderr, "Deprecated command line option: %s. Ignored, this option is now always on.\n", argv[i]);
+	  Swig_mark_arg(i);
+	} else if (strcmp(argv[i], "-py3") == 0) {
+	  Printf(stderr, "Deprecated command line option: %s. Ignored, this option is no longer supported.\n", argv[i]);
 	  Swig_mark_arg(i);
 	} else if (strcmp(argv[i], "-aliasobj0") == 0 ||
 		   strcmp(argv[i], "-buildnone") == 0 ||
@@ -443,7 +439,7 @@ public:
 		   strcmp(argv[i], "-oldrepr") == 0 ||
 		   strcmp(argv[i], "-outputtuple") == 0 ||
 		   strcmp(argv[i], "-proxydel") == 0) {
-	  Printf(stderr, "Deprecated command line option: %s. This option is no longer supported.\n", argv[i]);
+	  Printf(stderr, "Deprecated command line option: %s. This option is no longer available.\n", argv[i]);
 	  Swig_mark_arg(i);
 	  Exit(EXIT_FAILURE);
 	}
@@ -871,13 +867,8 @@ public:
 	Printv(f_shadow_py, "\n", f_shadow_begin, "\n", NIL);
 
       Printv(f_shadow_py, "\nfrom sys import version_info as _swig_python_version_info\n", NULL);
-      if (py3) {
-	Printv(f_shadow_py, "if _swig_python_version_info < (3, 0):\n", NULL);
-	Printv(f_shadow_py, tab4, "raise RuntimeError(\"Python 3.x or later required\")\n\n", NULL);
-      } else {
       Printv(f_shadow_py, "if _swig_python_version_info < (2, 7, 0):\n", NULL);
       Printv(f_shadow_py, tab4, "raise RuntimeError(\"Python 2.7 or later required\")\n\n", NULL);
-      }
 
       if (Len(f_shadow_after_begin) > 0)
 	Printv(f_shadow_py, f_shadow_after_begin, "\n", NIL);