Add -Wmissing-noreturn, and add attributes

Enable another useful compiler warning.  This one ensures that functions
which don't return are marked thus.

If found a couple of json-related error functions that ought to be
marked up.

CMakeLists.txt

@@ -222,11 +222,12 @@ ELSE()
     SET(CATA_WARNINGS
       "-Werror -Wall -Wextra \
        -Wmissing-declarations \
+       -Wmissing-noreturn \
        -Wold-style-cast \
        -Woverloaded-virtual \
        -Wsuggest-override \
-       -Wno-unknown-warning-option \
-       -Wpedantic")
+       -Wpedantic \
+       -Wno-unknown-warning-option")
     # Compact the whitespace in the warning string
     string(REGEX REPLACE "[\t ]+" " " CATA_WARNINGS "${CATA_WARNINGS}")
     SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${CATA_WARNINGS}")

Makefile

@@ -90,11 +90,12 @@ RELEASE_FLAGS =
 WARNINGS = \
   -Werror -Wall -Wextra \
   -Wmissing-declarations \
+  -Wmissing-noreturn \
   -Wold-style-cast \
   -Woverloaded-virtual \
+  -Wpedantic \
   -Wsuggest-override \
-  -Wno-unknown-warning-option \
-  -Wpedantic
+  -Wno-unknown-warning-option
 # Uncomment below to disable warnings
 #WARNINGS = -w
 DEBUGSYMS = -g

src/json.h

@@ -224,7 +224,6 @@ class JsonIn
             } catch( const io::InvalidEnumString & ) {
                 seek( old_offset ); // so the error message points to the correct place.
                 error( "invalid enumeration value" );
-                throw; // ^^ error already throws, but the compiler doesn't know that )-:
             }
         }
 
@@ -1013,8 +1012,8 @@ class JsonArray
         size_t size() const;
         bool empty();
         std::string str(); // copy array json as string
-        void throw_error( std::string err );
-        void throw_error( std::string err, int idx );
+        [[noreturn]] void throw_error( std::string err );
+        [[noreturn]] void throw_error( std::string err, int idx );
 
         // iterative access
         bool next_bool();
@@ -1138,7 +1137,7 @@ class JsonValue
             return seek().test_array();
         }
 
-        void throw_error( const std::string &err ) const {
+        [[noreturn]] void throw_error( const std::string &err ) const {
             seek().error( err );
         }