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_driver_impl/Cargo.toml b/compiler/rustc_driver_impl/Cargo.toml
index 73a1f79a020..cc4c5a0cacd 100644
--- a/compiler/rustc_driver_impl/Cargo.toml
+++ b/compiler/rustc_driver_impl/Cargo.toml
@@ -18,6 +18,7 @@ rustc_const_eval = { path = "../rustc_const_eval" }
 rustc_error_messages = { path = "../rustc_error_messages" }
 rustc_expand = { path = "../rustc_expand" }
 rustc_hir_typeck = { path = "../rustc_hir_typeck" }
+rustc_fluent_macro = { path = "../rustc_fluent_macro" }
 rustc_incremental = { path = "../rustc_incremental" }
 rustc_infer = { path = "../rustc_infer" }
 rustc_mir_build = { path = "../rustc_mir_build" }
diff --git a/compiler/rustc_driver_impl/src/lib.rs b/compiler/rustc_driver_impl/src/lib.rs
index b9f0e756e65..1a80b4fc314 100644
--- a/compiler/rustc_driver_impl/src/lib.rs
+++ b/compiler/rustc_driver_impl/src/lib.rs
@@ -28,10 +28,10 @@ use rustc_errors::{
     DiagnosticMessage, ErrorGuaranteed, PResult, SubdiagnosticMessage, TerminalUrl,
 };
 use rustc_feature::find_gated_cfg;
+use rustc_fluent_macro::fluent_messages;
 use rustc_interface::util::{self, collect_crate_types, get_codegen_backend};
 use rustc_interface::{interface, Queries};
 use rustc_lint::LintStore;
-use rustc_macros::fluent_messages;
 use rustc_metadata::locator;
 use rustc_session::config::{nightly_options, CG_OPTIONS, Z_OPTIONS};
 use rustc_session::config::{ErrorOutputType, Input, OutputType, PrintRequest, TrimmedDefPaths};