Auto merge of rust-lang#103693 - HKalbasi:master, r=oli-obk

Make rustc_target usable outside of rustc

I'm working on showing type size in rust-analyzer (rust-lang/rust-analyzer#13490) and I currently copied rustc code inside rust-analyzer, which works, but is bad. With this change, I would become able to use `rustc_target` and `rustc_index` directly in r-a, reducing the amount of copy needed.

This PR contains some feature flag to put nightly features behind them to make crates buildable on the stable compiler + makes layout related types generic over index type + removes interning of nested layouts.

Cargo.lock

@@ -3202,6 +3202,20 @@ dependencies = [
  "winapi",
 ]
 
+[[package]]
+name = "rustc_abi"
+version = "0.0.0"
+dependencies = [
+ "bitflags",
+ "rand 0.8.5",
+ "rand_xoshiro",
+ "rustc_data_structures",
+ "rustc_index",
+ "rustc_macros",
+ "rustc_serialize",
+ "tracing",
+]
+
 [[package]]
 name = "rustc_apfloat"
 version = "0.0.0"
@@ -4281,6 +4295,7 @@ name = "rustc_target"
 version = "0.0.0"
 dependencies = [
  "bitflags",
+ "rustc_abi",
  "rustc_data_structures",
  "rustc_feature",
  "rustc_index",
@@ -4336,6 +4351,7 @@ dependencies = [
  "rustc_infer",
  "rustc_middle",
  "rustc_span",
+ "rustc_target",
  "rustc_trait_selection",
  "smallvec",
  "tracing",
@@ -4360,8 +4376,6 @@ dependencies = [
 name = "rustc_ty_utils"
 version = "0.0.0"
 dependencies = [
- "rand 0.8.5",
- "rand_xoshiro",
  "rustc_data_structures",
  "rustc_errors",
  "rustc_hir",

compiler/rustc_abi/Cargo.toml

@@ -0,0 +1,24 @@
+[package]
+name = "rustc_abi"
+version = "0.0.0"
+edition = "2021"
+
+[dependencies]
+bitflags = "1.2.1"
+tracing = "0.1"
+rand = { version = "0.8.4", default-features = false, optional = true }
+rand_xoshiro = { version = "0.6.0", optional = true }
+rustc_data_structures = { path = "../rustc_data_structures", optional = true  }
+rustc_index = { path = "../rustc_index", default-features = false }
+rustc_macros = { path = "../rustc_macros", optional = true }
+rustc_serialize = { path = "../rustc_serialize", optional = true  }
+
+[features]
+default = ["nightly", "randomize"]
+randomize = ["rand", "rand_xoshiro"]
+nightly = [
+    "rustc_data_structures",
+    "rustc_index/nightly",
+    "rustc_macros",
+    "rustc_serialize",
+]