Ensure that the compiler properly supports regex

.gitignore

@@ -1 +1,2 @@
-palaver.so
+palaver.so
+test-regex

Makefile

@@ -1,7 +1,8 @@
 PALAVER_VERSION := $(shell git describe --tags --always --dirty 2> /dev/null || cat VERSION)
 CXXFLAGS := -Wno-unknown-pragmas -DPALAVER_VERSION=\"$(PALAVER_VERSION)\"
 
-palaver.so: palaver.cpp
+palaver.so: test palaver.cpp
+	@echo "Building palaver.so"
 	@CXXFLAGS="$(CXXFLAGS)" znc-buildmod palaver.cpp
 
 install: palaver.so
@@ -16,3 +17,9 @@ uninstall:
 	@echo "Uninstall palaver from $(HOME)/.znc/modules"
 	-rm -f $(HOME)/.znc/modules/palaver.so
 
+test-regex: test-regex.cpp
+	@c++ -std=c++11 test-regex.cpp -o test-regex
+
+.PHONY: test
+test: test-regex
+	@./test-regex

README.md

@@ -98,3 +98,10 @@ To solve this problem you can force IPv4 connections in ZNC using:
 ```
 /msg *status setbindhost 0.0.0.0
 ```
+
+###### Caught regex error
+
+This error indicates a problem with the C++ regex implementation in your C++
+compiler. Older versions of GCC have buggy implementations of regex and are
+incompatible with the module. GCC 4.9 or newer, and Clang are known to work.
+Please upgrade to a modern version.

test-regex.cpp

@@ -0,0 +1,23 @@
+#include <iostream>
+#include <regex>
+
+
+int main(int argc, const char *argv[]) {
+    std::smatch match;
+    std::string message = "Hello nickname.";
+    std::string matcher = "\\bnickname\\b";
+
+    try {
+        std::regex expression = std::regex(matcher, std::regex_constants::ECMAScript | std::regex_constants::icase);
+        std::regex_search(message, match, expression);
+    } catch (std::regex_error& error) {
+        std::cout << "Your C++ compiler doesn't properly support regex. Please upgrade to GCC 4.9, Clang or newer.\n";
+        return 1;
+    }
+
+    if (match.empty()) {
+        return 1;
+    }
+
+    return 0;
+}