src/librustc_ast_passes/show_span.rs

   1 //! Span debugger
   2 //!
   3 //! This module shows spans for all expressions in the crate
   4 //! to help with compiler debugging.
   5
   6 use std::str::FromStr;
   7
   8 use rustc_ast::ast;
   9 use rustc_ast::visit;
  10 use rustc_ast::visit::Visitor;
  11
  12 enum Mode {
  13     Expression,
  14     Pattern,
  15     Type,
  16 }
  17
  18 impl FromStr for Mode {
  19     type Err = ();
  20     fn from_str(s: &str) -> Result<Mode, ()> {
  21         let mode = match s {
  22             "expr" => Mode::Expression,
  23             "pat" => Mode::Pattern,
  24             "ty" => Mode::Type,
  25             _ => return Err(()),
  26         };
  27         Ok(mode)
  28     }
  29 }
  30
  31 struct ShowSpanVisitor<'a> {
  32     span_diagnostic: &'a rustc_errors::Handler,
  33     mode: Mode,
  34 }
  35
  36 impl<'a> Visitor<'a> for ShowSpanVisitor<'a> {
  37     fn visit_expr(&mut self, e: &'a ast::Expr) {
  38         if let Mode::Expression = self.mode {
  39             self.span_diagnostic.span_warn(e.span, "expression");
  40         }
  41         visit::walk_expr(self, e);
  42     }
  43
  44     fn visit_pat(&mut self, p: &'a ast::Pat) {
  45         if let Mode::Pattern = self.mode {
  46             self.span_diagnostic.span_warn(p.span, "pattern");
  47         }
  48         visit::walk_pat(self, p);
  49     }
  50
  51     fn visit_ty(&mut self, t: &'a ast::Ty) {
  52         if let Mode::Type = self.mode {
  53             self.span_diagnostic.span_warn(t.span, "type");
  54         }
  55         visit::walk_ty(self, t);
  56     }
  57
  58     fn visit_mac(&mut self, mac: &'a ast::MacCall) {
  59         visit::walk_mac(self, mac);
  60     }
  61 }
  62
  63 pub fn run(span_diagnostic: &rustc_errors::Handler, mode: &str, krate: &ast::Crate) {
  64     let mode = match mode.parse().ok() {
  65         Some(mode) => mode,
  66         None => return,
  67     };
  68     let mut v = ShowSpanVisitor { span_diagnostic, mode };
  69     visit::walk_crate(&mut v, krate);
  70 }