Auto merge of #67953 - cjgillot:split_infer, r=Zoxc

Split librustc::{traits,infer} to a separate crate rustc_infer

This is still very much work in progress.
Three functions are between dimensions (at the end of `rustc::traits`), waiting for some dependency breaking scheme.
Please tell me if the approach seems sound, and how you would like to split this PR up.

The formatting is deliberately off, to ease rebasing.

cc #65031

Author: bors

Cargo.lock

@@ -3111,8 +3111,6 @@ dependencies = [
  "bitflags",
  "byteorder",
  "chalk-engine",
- "fmt_macros",
- "graphviz",
  "jobserver",
  "log",
  "measureme",
@@ -3776,6 +3774,28 @@ dependencies = [
  "smallvec 1.0.0",
 ]
 
+[[package]]
+name = "rustc_infer"
+version = "0.0.0"
+dependencies = [
+ "fmt_macros",
+ "graphviz",
+ "log",
+ "rustc",
+ "rustc_attr",
+ "rustc_data_structures",
+ "rustc_error_codes",
+ "rustc_errors",
+ "rustc_hir",
+ "rustc_index",
+ "rustc_macros",
+ "rustc_session",
+ "rustc_span",
+ "rustc_target",
+ "smallvec 1.0.0",
+ "syntax",
+]
+
 [[package]]
 name = "rustc_interface"
 version = "0.0.0"
@@ -3796,6 +3816,7 @@ dependencies = [
  "rustc_expand",
  "rustc_hir",
  "rustc_incremental",
+ "rustc_infer",
  "rustc_lint",
  "rustc_metadata",
  "rustc_mir",
@@ -3838,6 +3859,7 @@ dependencies = [
  "rustc_feature",
  "rustc_hir",
  "rustc_index",
+ "rustc_infer",
  "rustc_session",
  "rustc_span",
  "rustc_target",
@@ -3907,6 +3929,7 @@ dependencies = [
  "rustc_errors",
  "rustc_hir",
  "rustc_index",
+ "rustc_infer",
  "rustc_lexer",
  "rustc_macros",
  "rustc_span",
@@ -3929,6 +3952,7 @@ dependencies = [
  "rustc_errors",
  "rustc_hir",
  "rustc_index",
+ "rustc_infer",
  "rustc_macros",
  "rustc_session",
  "rustc_span",
@@ -3969,6 +3993,7 @@ dependencies = [
  "rustc_feature",
  "rustc_hir",
  "rustc_index",
+ "rustc_infer",
  "rustc_session",
  "rustc_span",
  "rustc_target",
@@ -4019,6 +4044,7 @@ dependencies = [
  "rustc_expand",
  "rustc_feature",
  "rustc_hir",
+ "rustc_infer",
  "rustc_metadata",
  "rustc_session",
  "rustc_span",
@@ -4108,6 +4134,7 @@ dependencies = [
  "rustc",
  "rustc_data_structures",
  "rustc_hir",
+ "rustc_infer",
  "rustc_macros",
  "rustc_span",
  "rustc_target",
@@ -4123,6 +4150,7 @@ dependencies = [
  "rustc",
  "rustc_data_structures",
  "rustc_hir",
+ "rustc_infer",
  "rustc_span",
  "rustc_target",
 ]
@@ -4139,6 +4167,7 @@ dependencies = [
  "rustc_errors",
  "rustc_hir",
  "rustc_index",
+ "rustc_infer",
  "rustc_span",
  "rustc_target",
  "smallvec 1.0.0",

src/librustc/Cargo.toml

@@ -12,8 +12,6 @@ doctest = false
 [dependencies]
 arena = { path = "../libarena" }
 bitflags = "1.2.1"
-fmt_macros = { path = "../libfmt_macros" }
-graphviz = { path = "../libgraphviz" }
 jobserver = "0.1"
 scoped-tls = "1.0"
 log = { version = "0.4", features = ["release_max_level_info", "std"] }