genbindings: more const correctness

cmd/genbindings/emitcabi.go

@@ -45,6 +45,13 @@ func (p CppParameter) RenderTypeCabi() string {
 		ret = "ptrdiff_t"
 	}
 
+	if p.Const {
+		// This is needed for const-correctness for calling some overloads
+		// e.g. QShortcut ctor taking (QWidget* parent, const char* member) signal -
+		// the signal/slot requires that member is const, not just plain char*
+		ret = "const " + ret
+	}
+
 	if p.IsFlagType() {
 		ret = "int"
 

cmd/genbindings/emitgo.go

@@ -106,6 +106,9 @@ func (p CppParameter) parameterTypeCgo() string {
 		return "C.char"
 	}
 	tmp := strings.Replace(p.RenderTypeCabi(), `*`, "", -1)
+	if strings.HasPrefix(tmp, "const ") {
+		tmp = tmp[6:] // Constness doesn't survive the CABI boundary
+	}
 	if strings.HasPrefix(tmp, "unsigned ") {
 		tmp = "u" + tmp[9:] // Cgo uses uchar, uint instead of full name
 	}