Disable std::regex use for older gcc versions

src/common/conf_post.h

@@ -67,4 +67,11 @@ typedef int ssize_t;
 #  define PRETEND_USE(expr) ((void)(expr))
 #endif /* PRETEND_USE */
 
+#ifdef __GNUC__
+#include <features.h>
+#if ! __GNUC_PREREQ(6,0)
+#define NO_STD_REGEX 1
+#endif
+#endif
+
 #endif /* INCLUDED */

src/query/plaintorich.cpp

@@ -154,6 +154,7 @@ bool TextSplitPTR::matchGroups()
     return true;
 }
 
+#ifndef NO_STD_REGEX
 // Replace HTTP(s) urls in text/plain with proper HTML anchors so that
 // they become clickable in the preview. We don't make a lot of effort
 // for validating, or catching things which are probably urls but miss
@@ -165,6 +166,12 @@ static string activate_urls(const string& in)
 {
     return std::regex_replace(in, url_re, urlRep);
 }
+#else
+static string activate_urls(const string& in)
+{
+    return in;
+}
+#endif
 
 // Fix result text for display inside the gui text window.
 //

src/rcldb/rclabsfromtext.cpp

@@ -52,6 +52,7 @@ using namespace std;
 
 namespace Rcl {
 
+#ifndef NO_STD_REGEX
 //// Fragment cleanup
 // Chars we turn to spaces in the Snippets
 static const string cstr_nc("\n\r\x0c\\");
@@ -65,6 +66,12 @@ static string fixfrag(const string& infrag)
 {
     return std::regex_replace(neutchars(infrag, cstr_nc), fixfrag_re, punctRep);
 }
+#else
+static string fixfrag(const string& infrag)
+{
+    return infrag;
+}
+#endif
 
 
 // Fragment descriptor. A fragment is a text area with one or several

src/utils/pathut.cpp

@@ -1210,6 +1210,7 @@ bool urlisfileurl(const string& url)
     return url.find("file://") == 0;
 }
 
+#ifndef NO_STD_REGEX
 static std::regex
 re_uriparse("^(([^:/?#]+):)?(//([^/?#]*))?([^?#]*)(\\?([^#]*))?(#(.*))?",
             std::regex::extended);
@@ -1299,6 +1300,7 @@ ParsedUri::ParsedUri(std::string uri)
         fragment = mr[9].str();
     }
 }
+#endif // NO_STD_REGEX
 
 /// Directory reading interface. UTF-8 on Windows.
 class PathDirContents::Internal {