Compiler error messages for STL code

Compiler error messages for STL code are awkward. Here is an example:

{}
In file included from sim.cpp:5:
global.h: In function `void Simulate (int, map<id, Node *, less<Id>, 
allocator<Node *> >, map<Id, Link *, less<Id>, allocator<Link *> >, 
map<Id, Veh *, less<Id>, allocator<Veh *> >)':
global.h:358: conversion from `Link *' to non-scalar type `Link' 
requested

It is often helpful to first read the messages item by item and sometimes to re-arrange the messages:

• First comes where the corresponding file was included:

  
  

  {} 
  In file included from sim.cpp:5:
  

• This is followed by the function where the error happens:

  
  

  {}
  global.h: In function `void simulate (int, map<Id, Node *, less<Id>, 
  allocator<Node *> >, map<Id, Link *, less<Id>, allocator<Link *> >, 
  map<id, Veh *, less<Id>, allocator<Veh *> >)':
  

  As long as there is only one function void simulate(...), one can ignore the rest of this part of the error message. If one does not know about function overloading, this should be generically the case.

• Finally comes the real error message. Rearranging yields:

  
  

  {}
  global.h:358: conversion from 
    `Link *' 
  to non-scalar type 
    `Link' 
  requested
  

  That is, somehow the item on the right is a pointer to link, while the item on the left is a link.

  In this case, the offending line was

  
  

  {}
  Link link = l->second;
  

  The correct line would be

  
  

  {}
  Link* link = l->second;