Add `rustc_fluent_macro` to decouple fluent from `rustc_macros`

Fluent, with all the icu4x it brings in, takes quite some time to
compile. `fluent_messages!` is only needed in further downstream rustc
crates, but is blocking more upstream crates like `rustc_index`. By
splitting it out, we allow `rustc_macros` to be compiled earlier, which
speeds up `x check compiler` by about 5 seconds (and even more after the
needless dependency on `serde_json` is removed from
`rustc_data_structures`).

2 files changed, 2 insertions, 1 deletions

diff --git a/compiler/rustc_plugin_impl/Cargo.toml b/compiler/rustc_plugin_impl/Cargo.toml
index fa27bfc61d1..c930b3365fd 100644
--- a/compiler/rustc_plugin_impl/Cargo.toml
+++ b/compiler/rustc_plugin_impl/Cargo.toml
@@ -12,6 +12,7 @@ rustc_errors = { path = "../rustc_errors" }
 rustc_lint = { path = "../rustc_lint" }
 rustc_macros = { path = "../rustc_macros" }
 rustc_metadata = { path = "../rustc_metadata" }
+rustc_fluent_macro = { path = "../rustc_fluent_macro" }
 rustc_ast = { path = "../rustc_ast" }
 rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
diff --git a/compiler/rustc_plugin_impl/src/lib.rs b/compiler/rustc_plugin_impl/src/lib.rs
index 672189e22cf..faa7495ef9f 100644
--- a/compiler/rustc_plugin_impl/src/lib.rs
+++ b/compiler/rustc_plugin_impl/src/lib.rs
@@ -12,8 +12,8 @@
 #![deny(rustc::diagnostic_outside_of_impl)]
 
 use rustc_errors::{DiagnosticMessage, SubdiagnosticMessage};
+use rustc_fluent_macro::fluent_messages;
 use rustc_lint::LintStore;
-use rustc_macros::fluent_messages;
 
 mod errors;
 pub mod load;