Bison 2.5 compatibility patch and make target.

Makefile

@@ -19,6 +19,8 @@
 
 default: compile cleanautogen
 
+bison2: patch2 default unpatch2
+
 compile:
 	bison Monicelli.ypp
 	flex Monicelli.lpp
@@ -26,6 +28,13 @@ compile:
     -Wall -Wno-deprecated-register -std=c++11 -DYYDEBUG=0 -O2 \
     Parser.cpp lex.yy.cc Nodes.cpp main.cpp -o mcc
 
+patch2:
+	# Bison 2 compatibility patch
+	patch -r - -p 1 -N < bison2.patch || true
+
+unpatch2:
+	patch -p 1 -R < bison2.patch
+
 graph:
 	bison --graph Monicelli.y
 

README.md

@@ -17,7 +17,15 @@ executable is a matter of:
 
     make
 
-there are some other targets, which are of interest only for developers.
+A patch is provided for compatibility with Bison 2.5. If you can't really
+upgrade to Bison 3.0, and I strongly recommend that, you can always compile
+with:
+
+    make bison2
+
+However, note that this is not supported and might be removed in a future release.
+
+There are some other targets, which are of interest only for developers.
 
 Usage
 =====

bison2.patch

@@ -0,0 +1,28 @@
+diff --git a/Monicelli.ypp b/Monicelli.ypp
+index 028506d..9817f1e 100644
+--- a/Monicelli.ypp
++++ b/Monicelli.ypp
+@@ -23,7 +23,7 @@
+ }
+ 
+ %skeleton "lalr1.cc"
+-%require "3.0"
++%require "2.5"
+ %language "c++"
+ 
+ %defines
+@@ -31,9 +31,11 @@
+ %locations
+ %token-table
+ 
+-%define parse.error verbose
+-%define api.namespace {monicelli}
+-%define parser_class_name {Parser}
++%{
++#define YYERROR_VERBOSE
++%}
++%define namespace monicelli
++%define parser_class_name Parser
+ 
+ %lex-param {Scanner &scanner}
+ %parse-param {Scanner &scanner}