From 1e22e791ef4ab6b4e40c1b587d441cb252dc0303 Mon Sep 17 00:00:00 2001
From: Vadim Zeitlin <vz-swig@zeitlins.org>
Date: Mon, 21 Jan 2019 00:52:48 +0100
Subject: [PATCH] Always include default parameter values in Python autodoc
 strings

One of side effects of 15b369028fbfcee559d9f4a8e37e2d71428add29 was that
the default values were only included in Python doc strings if we could
be sure that they could be interpreted as valid Python expressions, but
this change was actually undesirable as it may be useful to see C++
expression for the default value in the doc string even when it isn't
valid in Python.

Undo this part of the change and extend autodoc unit test to check that
this stays fixed.

Closes #1271.
---
 Examples/test-suite/autodoc.i               | 10 ++++++++++
 Examples/test-suite/python/autodoc_runme.py |  2 ++
 Source/Modules/python.cxx                   | 14 ++++++++++++--
 3 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/Examples/test-suite/autodoc.i b/Examples/test-suite/autodoc.i
index a97a1634f..0e9356901 100644
--- a/Examples/test-suite/autodoc.i
+++ b/Examples/test-suite/autodoc.i
@@ -169,3 +169,13 @@ int process2(int from = 0, int _in = 1, int var = 2) { return from; }
 int process3(int from, int _in, int var) { return from; }
 int process4(int from = 0, int _in = 1, int var = 2) { return from; }
 %}
+
+// Autodoc for methods with default arguments not directly representable in
+// target language.
+%feature(autodoc,0) process_complex_defval;
+%feature("compactdefaultargs") process_complex_defval;
+%inline %{
+const int PROCESS_DEFAULT_VALUE = 17;
+typedef long int some_type;
+int process_complex_defval(int val = PROCESS_DEFAULT_VALUE, int factor = some_type(-1)) { return val*factor; }
+%}
diff --git a/Examples/test-suite/python/autodoc_runme.py b/Examples/test-suite/python/autodoc_runme.py
index d643d2247..d866cb990 100644
--- a/Examples/test-suite/python/autodoc_runme.py
+++ b/Examples/test-suite/python/autodoc_runme.py
@@ -207,3 +207,5 @@ check(inspect.getdoc(process), "process(int _from, int _in, int var) -> int")
 check(inspect.getdoc(process2), "process2(int _from=0, int _in=1, int var=2) -> int")
 check(inspect.getdoc(process3), "process3(int _from, int _in, int var) -> int")
 check(inspect.getdoc(process4), "process4(int _from=0, int _in=1, int var=2) -> int")
+
+check(inspect.getdoc(process_complex_defval), "process_complex_defval(val=PROCESS_DEFAULT_VALUE, factor=some_type(-1)) -> int")
diff --git a/Source/Modules/python.cxx b/Source/Modules/python.cxx
index fe681f768..f6aa4b869 100755
--- a/Source/Modules/python.cxx
+++ b/Source/Modules/python.cxx
@@ -1715,9 +1715,19 @@ public:
       // Write default value
       if (value && !calling) {
 	String *new_value = convertValue(value, Getattr(p, "type"));
+	if (new_value) {
+	  value = new_value;
+	} else {
+	  // Even if the value is not representable in the target language, still use it in the documentaiton, for compatibility with the previous SWIG versions
+	  // and because it can still be useful to see the C++ expression there.
+	  Node *lookup = Swig_symbol_clookup(value, 0);
+	  if (lookup)
+	    value = Getattr(lookup, "sym:name");
+	}
+	Printf(doc, "=%s", value);
+
 	if (new_value)
-	  Printf(doc, "=%s", new_value);
-	Delete(new_value);
+	  Delete(new_value);
       }
       Delete(type_str);
       Delete(made_name);