diff options
Diffstat (limited to 'compiler/rustc_macros/src/query.rs')
| -rw-r--r-- | compiler/rustc_macros/src/query.rs | 38 |
1 files changed, 36 insertions, 2 deletions
diff --git a/compiler/rustc_macros/src/query.rs b/compiler/rustc_macros/src/query.rs index 12990ae2d94..6d876784be6 100644 --- a/compiler/rustc_macros/src/query.rs +++ b/compiler/rustc_macros/src/query.rs @@ -5,8 +5,8 @@ use syn::parse::{Parse, ParseStream, Result}; use syn::punctuated::Punctuated; use syn::spanned::Spanned; use syn::{ - braced, parenthesized, parse_macro_input, AttrStyle, Attribute, Block, Error, Expr, Ident, - ReturnType, Token, Type, + braced, parenthesized, parse_macro_input, parse_quote, AttrStyle, Attribute, Block, Error, + Expr, Ident, ReturnType, Token, Type, }; mod kw { @@ -272,6 +272,40 @@ fn process_modifiers(query: &mut Query) -> QueryModifiers { if desc.is_some() { panic!("duplicate modifier `desc` for query `{}`", query.name); } + // If there are no doc-comments, give at least some idea of what + // it does by showing the query description. + if query.doc_comments.is_empty() { + use ::syn::*; + let mut list = list.iter(); + let format_str: String = match list.next() { + Some(&Expr::Lit(ExprLit { lit: Lit::Str(ref lit_str), .. })) => { + lit_str.value().replace("`{}`", "{}") // We add them later anyways for consistency + } + _ => panic!("Expected a string literal"), + }; + let mut fmt_fragments = format_str.split("{}"); + let mut doc_string = fmt_fragments.next().unwrap().to_string(); + list.map(::quote::ToTokens::to_token_stream).zip(fmt_fragments).for_each( + |(tts, next_fmt_fragment)| { + use ::core::fmt::Write; + write!( + &mut doc_string, + " `{}` {}", + tts.to_string().replace(" . ", "."), + next_fmt_fragment, + ) + .unwrap(); + }, + ); + let doc_string = format!( + "[query description - consider adding a doc-comment!] {}", + doc_string + ); + let comment = parse_quote! { + #[doc = #doc_string] + }; + query.doc_comments.push(comment); + } desc = Some((tcx, list)); } QueryModifier::FatalCycle => { |