Fixes for classes with the same name in different namespaces

Includes the majority of patch #1484.
Excludes changes in typepass.cxx for specializations which have no effect
on the duplicate_class_name_in_ns testcase, nor the rest of the test-suite.

CHANGES.current

@@ -7,6 +7,13 @@ the issue number to the end of the URL: https://github.com/swig/swig/issues/
 Version 4.1.0 (in progress)
 ===========================
 
+2022-09-19: wsfulton
+            #1484 Fixes for class inheritance with the same name in different namespaces
+            such as:
+
+              namespace A { class Bar {}; }
+              namespace B { template<typename T, typename U> class Bar : public A::Bar {}; }
+
 2022-09-19: wsfulton
             #2316 Remove swig.spec file and srcrpm makefile target. These are very out of date
             and don't seem to be used by RPM based Linux distributions which have their

Examples/test-suite/common.mk

@@ -223,6 +223,7 @@ CPP_TEST_CASES += \
 	director_void \
 	director_wombat \
 	disown \
+	duplicate_class_name_in_ns \
 	dynamic_cast \
 	empty \
 	enum_ignore \

Examples/test-suite/duplicate_class_name_in_ns.i

@@ -0,0 +1,88 @@
+%module duplicate_class_name_in_ns
+
+%rename(XA) A::X;
+%rename(XB) B::X;
+
+%inline %{
+
+namespace A
+{
+    class X
+    {
+    public:
+        X(){};
+    };
+
+    template<typename T>
+    class Foo
+    {
+    public:
+        Foo(){};
+    };
+
+    class Bar
+    {
+    public:
+        Bar(){};
+    };
+
+    template<typename T>
+    class Baz
+    {
+    public:
+        Baz(){};
+    };
+}
+
+namespace B
+{
+    // non-template derived from non-template
+    class X : public A::X
+    {
+    public:
+        X(){};
+        A::X do_x(){return A::X();}
+    };
+
+    // template derived from template with different template args
+    template<typename T, typename U>
+    class Foo : public A::Foo<U>
+    {
+    public:
+        Foo(){};
+        A::Foo<U> do_foo(){return A::Foo<U>();}
+    };
+
+    // template derived from non-template
+    template<typename T, typename U>
+    class Bar : public A::Bar
+    {
+    public:
+        Bar(){};
+        A::Bar do_bar(){return A::Bar();}
+    };
+
+    // template derived from template with same template args
+    template<typename T>
+    class Baz : public A::Baz<T>
+    {
+    public:
+        Baz(){};
+        A::Baz<T> do_baz(){return A::Baz<T>();}
+    };
+}
+
+%}
+
+%template(AFoo) A::Foo<double>;
+%template(ABaz) A::Baz<double>;
+%template(BFoo) B::Foo<int, double>;
+%template(BBar) B::Bar<int, double>;
+%template(BBaz) B::Baz<double>;
+
+%inline %{
+    A::X get_a_x() {B::X x; return x.do_x();}
+    A::Foo<double> get_a_foo() {B::Foo<int, double> x; return x.do_foo();}
+    A::Bar get_a_bar() {B::Bar<int, double> x; return x.do_bar();}
+    A::Baz<double> get_a_baz() {B::Baz<double> x; return x.do_baz();}
+%}

Source/CParse/templ.c

@@ -335,6 +335,7 @@ int Swig_cparse_template_expand(Node *n, String *rname, ParmList *tparms, Symtab
 
     if (tp) {
       Symtab *tsdecl = Getattr(n, "sym:symtab");
+      String *tsname = Getattr(n, "sym:name");
       while (p && tp) {
 	String *name, *value, *valuestr, *tmp, *tmpr;
 	int sz, i;
@@ -376,11 +377,18 @@ int Swig_cparse_template_expand(Node *n, String *rname, ParmList *tparms, Symtab
 	  sz = Len(typelist);
 	  for (i = 0; i < sz; i++) {
 	    String *s = Getitem(typelist, i);
-	    /*      Replace(s,name,value, DOH_REPLACE_ID); */
-	    /*      Printf(stdout,"name = '%s', value = '%s', tbase = '%s', iname='%s' s = '%s' --> ", name, dvalue, tbase, iname, s); */
-	    SwigType_typename_replace(s, name, dvalue);
-	    SwigType_typename_replace(s, tbase, iname);
-	    /*      Printf(stdout,"'%s'\n", s); */
+	    /*
+	      The approach of 'trivially' replacing template arguments is kind of fragile.
+	      In particular if types with similar name in different namespaces appear.
+	      We will not replace template args if a type/class exists with the same
+	      name which is not a template.
+	    */
+	    Node * tynode = Swig_symbol_clookup(s, 0);
+	    String *tyname  = tynode ? Getattr(tynode, "sym:name") : 0;
+	    if (!tyname || !tsname || !Equal(tyname, tsname) || Getattr(tynode, "templatetype")) {
+	      SwigType_typename_replace(s, name, dvalue);
+	      SwigType_typename_replace(s, tbase, iname);
+	    }
 	  }
 
 	  tmp = NewStringf("#%s", name);