Update docs to specify exception type

README.md

@@ -20,7 +20,7 @@ NOTE: the file must exist before creating a mapping.
 
 There are three ways to map a file into memory:
 
-- Using the constructor, which throws on failure:
+- Using the constructor, which throws a `std::system_error` on failure:
 ```c++
 mio::mmap_source mmap(path, offset, size_to_map);
 ```

include/mio/mmap.hpp

@@ -104,8 +104,9 @@ public:
     basic_mmap() = default;
 
     /**
-     * The same as invoking the `map` function, except any error that may occur while
-     * establishing the mapping is thrown.
+     * The same as invoking the `map` function, except any error that may occur
+     * while establishing the mapping is wrapped in a `std::system_error` and is
+     * thrown.
      */
     template<typename String>
     basic_mmap(const String& path, const size_type offset = 0, const size_type length = map_entire_file)
@@ -116,8 +117,9 @@ public:
     }
 
     /**
-     * The same as invoking the `map` function, except any error that may occur while
-     * establishing the mapping is thrown.
+     * The same as invoking the `map` function, except any error that may occur
+     * while establishing the mapping is wrapped in a `std::system_error` and is
+     * thrown.
      */
     basic_mmap(const handle_type handle, const size_type offset = 0, const size_type length = map_entire_file)
     {

include/mio/shared_mmap.hpp

@@ -88,8 +88,9 @@ public:
     }
 
     /**
-     * The same as invoking the `map` function, except any error that may occur while
-     * establishing the mapping is thrown.
+     * The same as invoking the `map` function, except any error that may occur
+     * while establishing the mapping is wrapped in a `std::system_error` and is
+     * thrown.
      */
     template<typename String>
     basic_shared_mmap(const String& path, const size_type offset = 0, const size_type length = map_entire_file)
@@ -100,8 +101,9 @@ public:
     }
 
     /**
-     * The same as invoking the `map` function, except any error that may occur while
-     * establishing the mapping is thrown.
+     * The same as invoking the `map` function, except any error that may occur
+     * while establishing the mapping is wrapped in a `std::system_error` and is
+     * thrown.
      */
     basic_shared_mmap(const handle_type handle, const size_type offset = 0, const size_type length = map_entire_file)
     {