From e186dc13b7a2c31eeea8e4918504ff85b7244765 Mon Sep 17 00:00:00 2001
From: William S Fulton <wsf@fultondesigns.co.uk>
Date: Mon, 10 Mar 2014 07:07:39 +0000
Subject: [PATCH] C++11 constexpr variables support added

---
 Doc/Manual/CPlusPlus11.html           | 21 ++++++++++----------
 Examples/test-suite/cpp11_constexpr.i | 28 ++++++++++++++++++++++++---
 Source/CParse/parser.y                |  2 +-
 3 files changed, 36 insertions(+), 15 deletions(-)

diff --git a/Doc/Manual/CPlusPlus11.html b/Doc/Manual/CPlusPlus11.html
index 86a042d78..585a70e63 100644
--- a/Doc/Manual/CPlusPlus11.html
+++ b/Doc/Manual/CPlusPlus11.html
@@ -107,7 +107,7 @@ For example, ignore the move constructor:
 </pre></div>
 
 <p>
-The plan is to ignore them by default in a future version of SWIG. Note that both normal assignment operators as well as move assignment operators are ignored by default in most target languages with the following warning:
+The plan is to ignore move constructors by default in a future version of SWIG. Note that both normal assignment operators as well as move assignment operators are ignored by default in most target languages with the following warning:
 </p>
 
 <div class="shell">
@@ -120,20 +120,19 @@ example.i:18: Warning 503: Can't wrap 'operator =' unless renamed to a valid ide
 <H3><a name="CPlusPlus11_generalized_constant_expressions"></a>7.2.2 Generalized constant expressions</H3>
 
 
-<p>SWIG correctly parses the keyword <tt>constexpr</tt>, but ignores its functionality. Constant functions cannot be used as constants.</p>
+<p>SWIG parses and identifies the keyword <tt>constexpr</tt>, but cannot fully utilise it.
+These C++ compile time constants are usable as runtime constants from the target languages.
+Below shows example usage for assigning a C++ compile time constant from a compile time constant function:
+</p>
 
 <div class="code"><pre>
-constexpr int myConstFunc() { return 10; }
-const int a = myConstFunc(); // results in error
+constexpr int XXX() { return 10; }
+constexpr int YYY = XXX() + 100;
 </pre></div>
 
-<p>Users needs to use values or predefined constants when defining the new constant value:</p>
-
-<div class="code"><pre>
-#define MY_CONST 10
-constexpr int myConstFunc() { return MY_CONST; }
-const int a = MY_CONST; // ok
-</pre></div>
+<p>
+When either of these is used from a target language, a runtime call is made to obtain the underlying constant.
+</p>
 
 <H3><a name="CPlusPlus11_extern_template"></a>7.2.3 Extern template</H3>
 
diff --git a/Examples/test-suite/cpp11_constexpr.i b/Examples/test-suite/cpp11_constexpr.i
index 95fe5fa2b..412b8132a 100644
--- a/Examples/test-suite/cpp11_constexpr.i
+++ b/Examples/test-suite/cpp11_constexpr.i
@@ -4,9 +4,31 @@
 %module cpp11_constexpr
 
 %inline %{
-class TestClass {
-public:
-  constexpr int func() { return 10; }
+constexpr int AAA = 10;
+constexpr const int BBB = 20;
+constexpr int CCC() { return 30; }
+constexpr const int DDD() { return 40; }
+
+constexpr int XXX() { return 10; }
+constexpr int YYY = XXX() + 100;
+
+struct ConstExpressions {
+  static constexpr const int JJJ = 100;
+  static constexpr int KKK = 200;
+  static const int LLL = 300;
+  constexpr int MMM() { return 400; }
+  constexpr const int NNN() { return 500; }
 };
 %}
 
+%{
+int Array10[AAA];
+int Array20[BBB];
+int Array30[CCC()];
+int Array40[DDD()];
+int Array100[ConstExpressions::JJJ];
+int Array200[ConstExpressions::KKK];
+int Array300[ConstExpressions::LLL];
+//int Array400[ConstExpressions::MMM()];
+//int Array500[ConstExpressions::NNN()];
+%}
diff --git a/Source/CParse/parser.y b/Source/CParse/parser.y
index 1bd351560..0ed438e90 100644
--- a/Source/CParse/parser.y
+++ b/Source/CParse/parser.y
@@ -412,7 +412,7 @@ static void add_symbols(Node *n) {
 	    } else {
 	      ty = type;
 	    }
-	    if (!SwigType_ismutable(ty)) {
+	    if (!SwigType_ismutable(ty) || (storage && Strstr(storage, "constexpr"))) {
 	      SetFlag(n,"hasconsttype");
 	      SetFlag(n,"feature:immutable");
 	    }