Introduce rustc_session crate

Cargo.lock

@@ -3884,6 +3884,18 @@ dependencies = [
  "syntax_pos",
 ]
 
+[[package]]
+name = "rustc_session"
+version = "0.0.0"
+dependencies = [
+ "log",
+ "rustc_data_structures",
+ "libserialize",
+ "rustc_errors",
+ "serialize",
+ "syntax_pos",
+]
+
 [[package]]
 name = "rustc_target"
 version = "0.0.0"

src/librustc/Cargo.toml

@@ -39,3 +39,4 @@ rustc_fs_util = { path = "../librustc_fs_util" }
 smallvec = { version = "1.0", features = ["union", "may_dangle"] }
 measureme = "0.4"
 rustc_error_codes = { path = "../librustc_error_codes" }
+rustc_session = { path = "../librustc_session" }

src/librustc_session/Cargo.toml

@@ -0,0 +1,16 @@
+[package]
+authors = ["The Rust Project Developers"]
+name = "rustc_session"
+version = "0.0.0"
+edition = "2018"
+
+[lib]
+name = "rustc_session"
+path = "lib.rs"
+
+[dependencies]
+log = "0.4"
+rustc_errors = { path = "../librustc_errors" }
+rustc_serialize = { path = "../libserialize", package = "serialize" }
+rustc_data_structures = { path = "../librustc_data_structures" }
+syntax_pos = { path = "../libsyntax_pos" }