Use feature (#4127)

Author: topecongiro

Cargo.lock

@@ -1,7 +1,5 @@
 [workspace]
 members = [
   "rustfmt-bin",
-  "rustfmt-config",
-  "rustfmt-emitter",
   "rustfmt-lib",
 ]

rustfmt-core/Cargo.toml

@@ -8,8 +8,25 @@ license = "Apache-2.0/MIT"
 repository = "https://github.com/rust-lang/rustfmt"
 
 [features]
+# FIXME: Refactor so that rustfmt can be built without config or emitter.
+default = ["config", "emitter"]
 generic-simd = ["bytecount/generic-simd"]
 
+config = [
+  "dirs",
+  "rustfmt-config_proc_macro",
+  "serde",
+  "serde_json",
+  "toml",
+]
+
+emitter = [
+  "config",
+  "diff",
+  "serde",
+  "serde_json",
+]
+
 [dependencies]
 annotate-snippets = { version = "0.6", features = ["ansi_term"] }
 anyhow = "1.0"
@@ -19,14 +36,20 @@ itertools = "0.8"
 lazy_static = "1.0.0"
 log = "0.4"
 regex = "1.0"
-rustfmt_configuration = { path = "../rustfmt-config", version = "2.0.0-rc.1" }
-rustfmt_emitter =  { path = "../rustfmt-emitter", version = "2.0.0-rc.1" }
 term = "0.6"
 thiserror = "1.0"
 unicode_categories = "0.1.1"
 unicode-segmentation = "1.0.0"
 unicode-width = "0.1.5"
 
+# Optional dependencies
+diff = { version = "0.1", optional = true}
+dirs = { version = "2.0", optional = true }
+rustfmt-config_proc_macro = { version = "0.4", path = "config_proc_macro", optional = true }
+serde = { version = "1.0", features = ["derive"], optional = true }
+serde_json = { version = "1.0", optional = true }
+toml = { version = "0.5", optional = true }
+
 [dev-dependencies]
 env_logger = "0.7"