Use natural (digit-sequence-aware) sorting for wildcard expansion

Fixes #1993

complete.cpp

@@ -324,9 +324,9 @@ completion_t &completion_t::operator=(const completion_t &him)
     return *this;
 }
 
-bool completion_t::is_alphabetically_less_than(const completion_t &a, const completion_t &b)
+bool completion_t::is_naturally_less_than(const completion_t &a, const completion_t &b)
 {
-    return a.completion < b.completion;
+    return wcsfilecmp(a.completion.c_str(), b.completion.c_str()) < 0;
 }
 
 bool completion_t::is_alphabetically_equal_to(const completion_t &a, const completion_t &b)

complete.h

@@ -123,7 +123,9 @@ class completion_t
     completion_t &operator=(const completion_t &);
 
     /* Compare two completions. No operating overlaoding to make this always explicit (there's potentially multiple ways to compare completions). */
-    static bool is_alphabetically_less_than(const completion_t &a, const completion_t &b);
+    
+    /* "Naturally less than" means in a natural ordering, where digits are treated as numbers. For example, foo10 is naturally greater than foo2 (but alphabetically less than it) */
+    static bool is_naturally_less_than(const completion_t &a, const completion_t &b);
     static bool is_alphabetically_equal_to(const completion_t &a, const completion_t &b);
 };
 

expand.cpp

@@ -1923,7 +1923,7 @@ int expand_string(const wcstring &input, std::vector<completion_t> &output, expa
                     case 1:
                     {
                         res = EXPAND_WILDCARD_MATCH;
-                        std::sort(expanded.begin(), expanded.end(), completion_t::is_alphabetically_less_than);
+                        std::sort(expanded.begin(), expanded.end(), completion_t::is_naturally_less_than);
                         out->insert(out->end(), expanded.begin(), expanded.end());
                         break;
                     }

reader.cpp

@@ -867,7 +867,7 @@ bool reader_data_t::expand_abbreviation_as_necessary(size_t cursor_backtrack)
 /** Sorts and remove any duplicate completions in the list. */
 static void sort_and_make_unique(std::vector<completion_t> &l)
 {
-    sort(l.begin(), l.end(), completion_t::is_alphabetically_less_than);
+    sort(l.begin(), l.end(), completion_t::is_naturally_less_than);
     l.erase(std::unique(l.begin(), l.end(), completion_t::is_alphabetically_equal_to), l.end());
 }