compiler/rustc_expand/src/proc_macro.rs

   1 use crate::base::{self, *};
   2 use crate::proc_macro_server;
   3
   4 use rustc_ast as ast;
   5 use rustc_ast::ptr::P;
   6 use rustc_ast::token;
   7 use rustc_ast::tokenstream::{CanSynthesizeMissingTokens, TokenStream, TokenTree};
   8 use rustc_data_structures::sync::Lrc;
   9 use rustc_errors::ErrorReported;
  10 use rustc_parse::nt_to_tokenstream;
  11 use rustc_parse::parser::ForceCollect;
  12 use rustc_span::{Span, DUMMY_SP};
  13
  14 const EXEC_STRATEGY: pm::bridge::server::SameThread = pm::bridge::server::SameThread;
  15
  16 pub struct BangProcMacro {
  17     pub client: pm::bridge::client::Client<fn(pm::TokenStream) -> pm::TokenStream>,
  18 }
  19
  20 impl base::ProcMacro for BangProcMacro {
  21     fn expand<'cx>(
  22         &self,
  23         ecx: &'cx mut ExtCtxt<'_>,
  24         span: Span,
  25         input: TokenStream,
  26     ) -> Result<TokenStream, ErrorReported> {
  27         let server = proc_macro_server::Rustc::new(ecx);
  28         self.client.run(&EXEC_STRATEGY, server, input, ecx.ecfg.proc_macro_backtrace).map_err(|e| {
  29             let mut err = ecx.struct_span_err(span, "proc macro panicked");
  30             if let Some(s) = e.as_str() {
  31                 err.help(&format!("message: {}", s));
  32             }
  33             err.emit();
  34             ErrorReported
  35         })
  36     }
  37 }
  38
  39 pub struct AttrProcMacro {
  40     pub client: pm::bridge::client::Client<fn(pm::TokenStream, pm::TokenStream) -> pm::TokenStream>,
  41 }
  42
  43 impl base::AttrProcMacro for AttrProcMacro {
  44     fn expand<'cx>(
  45         &self,
  46         ecx: &'cx mut ExtCtxt<'_>,
  47         span: Span,
  48         annotation: TokenStream,
  49         annotated: TokenStream,
  50     ) -> Result<TokenStream, ErrorReported> {
  51         let server = proc_macro_server::Rustc::new(ecx);
  52         self.client
  53             .run(&EXEC_STRATEGY, server, annotation, annotated, ecx.ecfg.proc_macro_backtrace)
  54             .map_err(|e| {
  55                 let mut err = ecx.struct_span_err(span, "custom attribute panicked");
  56                 if let Some(s) = e.as_str() {
  57                     err.help(&format!("message: {}", s));
  58                 }
  59                 err.emit();
  60                 ErrorReported
  61             })
  62     }
  63 }
  64
  65 pub struct ProcMacroDerive {
  66     pub client: pm::bridge::client::Client<fn(pm::TokenStream) -> pm::TokenStream>,
  67 }
  68
  69 impl MultiItemModifier for ProcMacroDerive {
  70     fn expand(
  71         &self,
  72         ecx: &mut ExtCtxt<'_>,
  73         span: Span,
  74         _meta_item: &ast::MetaItem,
  75         item: Annotatable,
  76     ) -> ExpandResult<Vec<Annotatable>, Annotatable> {
  77         // We need special handling for statement items
  78         // (e.g. `fn foo() { #[derive(Debug)] struct Bar; }`)
  79         let mut is_stmt = false;
  80         let item = match item {
  81             Annotatable::Item(item) => token::NtItem(item),
  82             Annotatable::Stmt(stmt) => {
  83                 is_stmt = true;
  84                 assert!(stmt.is_item());
  85
  86                 // A proc macro can't observe the fact that we're passing
  87                 // them an `NtStmt` - it can only see the underlying tokens
  88                 // of the wrapped item
  89                 token::NtStmt(stmt.into_inner())
  90             }
  91             _ => unreachable!(),
  92         };
  93         let input = if crate::base::pretty_printing_compatibility_hack(&item, &ecx.sess.parse_sess)
  94         {
  95             TokenTree::token(token::Interpolated(Lrc::new(item)), DUMMY_SP).into()
  96         } else {
  97             nt_to_tokenstream(&item, &ecx.sess.parse_sess, CanSynthesizeMissingTokens::No)
  98         };
  99
 100         let server = proc_macro_server::Rustc::new(ecx);
 101         let stream =
 102             match self.client.run(&EXEC_STRATEGY, server, input, ecx.ecfg.proc_macro_backtrace) {
 103                 Ok(stream) => stream,
 104                 Err(e) => {
 105                     let mut err = ecx.struct_span_err(span, "proc-macro derive panicked");
 106                     if let Some(s) = e.as_str() {
 107                         err.help(&format!("message: {}", s));
 108                     }
 109                     err.emit();
 110                     return ExpandResult::Ready(vec![]);
 111                 }
 112             };
 113
 114         let error_count_before = ecx.sess.parse_sess.span_diagnostic.err_count();
 115         let mut parser =
 116             rustc_parse::stream_to_parser(&ecx.sess.parse_sess, stream, Some("proc-macro derive"));
 117         let mut items = vec![];
 118
 119         loop {
 120             match parser.parse_item(ForceCollect::No) {
 121                 Ok(None) => break,
 122                 Ok(Some(item)) => {
 123                     if is_stmt {
 124                         items.push(Annotatable::Stmt(P(ecx.stmt_item(span, item))));
 125                     } else {
 126                         items.push(Annotatable::Item(item));
 127                     }
 128                 }
 129                 Err(mut err) => {
 130                     err.emit();
 131                     break;
 132                 }
 133             }
 134         }
 135
 136         // fail if there have been errors emitted
 137         if ecx.sess.parse_sess.span_diagnostic.err_count() > error_count_before {
 138             ecx.struct_span_err(span, "proc-macro derive produced unparseable tokens").emit();
 139         }
 140
 141         ExpandResult::Ready(items)
 142     }
 143 }