Function entry_symbol 

pub fn entry_symbol(prefix: &str, name: &str) -> String

One module’s entry symbol: the prefix, then the declared name with every character a symbol cannot carry replaced by _.

lumen-module-macros spells the same names at the module’s compile time, from the name its author passed to lumen_module!. The two spellings are the contract between a module and the loader: a module declared under a name it was not built with reads as a library exporting nothing. They live here rather than beside the loader because a link kit spells them with no loader in the build at all.