compiler/rustc_fluent_macro/src/lib.rs

   1 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
   2 #![doc(rust_logo)]
   3 #![allow(internal_features)]
   4 #![feature(rustdoc_internals)]
   5 #![feature(proc_macro_diagnostic)]
   6 #![feature(proc_macro_span)]
   7 #![deny(rustc::untranslatable_diagnostic)]
   8 #![deny(rustc::diagnostic_outside_of_impl)]
   9 #![allow(rustc::default_hash_types)]
  10
  11 use proc_macro::TokenStream;
  12
  13 mod fluent;
  14
  15 /// Implements the `fluent_messages` macro, which performs compile-time validation of the
  16 /// compiler's Fluent resources (i.e. that the resources parse and don't multiply define the same
  17 /// messages) and generates constants that make using those messages in diagnostics more ergonomic.
  18 ///
  19 /// For example, given the following invocation of the macro..
  20 ///
  21 /// ```ignore (rust)
  22 /// fluent_messages! { "./typeck.ftl" }
  23 /// ```
  24 /// ..where `typeck.ftl` has the following contents..
  25 ///
  26 /// ```fluent
  27 /// typeck_field_multiply_specified_in_initializer =
  28 ///     field `{$ident}` specified more than once
  29 ///     .label = used more than once
  30 ///     .label_previous_use = first use of `{$ident}`
  31 /// ```
  32 /// ...then the macro parse the Fluent resource, emitting a diagnostic if it fails to do so, and
  33 /// will generate the following code:
  34 ///
  35 /// ```ignore (rust)
  36 /// pub static DEFAULT_LOCALE_RESOURCE: &'static [&'static str] = include_str!("./typeck.ftl");
  37 ///
  38 /// mod fluent_generated {
  39 ///     mod typeck {
  40 ///         pub const field_multiply_specified_in_initializer: DiagnosticMessage =
  41 ///             DiagnosticMessage::fluent("typeck_field_multiply_specified_in_initializer");
  42 ///         pub const field_multiply_specified_in_initializer_label_previous_use: DiagnosticMessage =
  43 ///             DiagnosticMessage::fluent_attr(
  44 ///                 "typeck_field_multiply_specified_in_initializer",
  45 ///                 "previous_use_label"
  46 ///             );
  47 ///     }
  48 /// }
  49 /// ```
  50 /// When emitting a diagnostic, the generated constants can be used as follows:
  51 ///
  52 /// ```ignore (rust)
  53 /// let mut err = sess.struct_span_err(
  54 ///     span,
  55 ///     fluent::typeck::field_multiply_specified_in_initializer
  56 /// );
  57 /// err.span_default_label(span);
  58 /// err.span_label(
  59 ///     previous_use_span,
  60 ///     fluent::typeck::field_multiply_specified_in_initializer_label_previous_use
  61 /// );
  62 /// err.emit();
  63 /// ```
  64 ///
  65 /// Note: any crate using this macro must also have a dependency on
  66 /// `rustc_errors`, because the generated code refers to things from that
  67 /// crate.
  68 #[proc_macro]
  69 pub fn fluent_messages(input: TokenStream) -> TokenStream {
  70     fluent::fluent_messages(input)
  71 }