Rollup merge of #82860 - LeSeulArtichaut:unpretty-thir, r=spastorino

Add `-Z unpretty` flag for the THIR

This adds a new perma-unstable flag, `-Zunpretty=thir-tree`, that dumps the raw THIR tree for each body in the crate.

Implements the THIR part of MCP rust-lang/compiler-team#408, helps with rust-lang/rustc-dev-guide#1062.
Depends on #82495, blocked on that. Only the two last commits are added by this PR.
r? ```@spastorino``` cc ```@estebank```

9 files changed, 87 insertions, 62 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 25039b5cbd9..2c9eaebb5fd 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -3870,6 +3870,7 @@ dependencies = [
  "rustc_metadata",
  "rustc_middle",
  "rustc_mir",
+ "rustc_mir_build",
  "rustc_parse",
  "rustc_plugin_impl",
  "rustc_save_analysis",
@@ -3877,6 +3878,7 @@ dependencies = [
  "rustc_session",
  "rustc_span",
  "rustc_target",
+ "rustc_typeck",
  "tracing",
  "tracing-subscriber",
  "tracing-tree",
diff --git a/compiler/rustc_driver/Cargo.toml b/compiler/rustc_driver/Cargo.toml
index 93c6ec04e4f..c521f2041d8 100644
--- a/compiler/rustc_driver/Cargo.toml
+++ b/compiler/rustc_driver/Cargo.toml
@@ -34,6 +34,8 @@ rustc_interface = { path = "../rustc_interface" }
 rustc_serialize = { path = "../rustc_serialize" }
 rustc_ast = { path = "../rustc_ast" }
 rustc_span = { path = "../rustc_span" }
+rustc_mir_build = { path = "../rustc_mir_build" }
+rustc_typeck = { path = "../rustc_typeck" }
 
 [target.'cfg(windows)'.dependencies]
 winapi = { version = "0.3", features = ["consoleapi", "debugapi", "processenv"] }
diff --git a/compiler/rustc_driver/src/pretty.rs b/compiler/rustc_driver/src/pretty.rs
index 38c493a920d..5512bd74453 100644
--- a/compiler/rustc_driver/src/pretty.rs
+++ b/compiler/rustc_driver/src/pretty.rs
@@ -9,12 +9,14 @@ use rustc_hir_pretty as pprust_hir;
 use rustc_middle::hir::map as hir_map;
 use rustc_middle::ty::{self, TyCtxt};
 use rustc_mir::util::{write_mir_graphviz, write_mir_pretty};
+use rustc_mir_build::thir;
 use rustc_session::config::{Input, PpAstTreeMode, PpHirMode, PpMode, PpSourceMode};
 use rustc_session::Session;
 use rustc_span::symbol::Ident;
 use rustc_span::FileName;
 
 use std::cell::Cell;
+use std::fmt::Write;
 use std::path::Path;
 
 pub use self::PpMode::*;
@@ -469,6 +471,21 @@ pub fn print_after_hir_lowering<'tcx>(
             format!("{:#?}", krate)
         }),
 
+        ThirTree => {
+            let mut out = String::new();
+            abort_on_err(rustc_typeck::check_crate(tcx), tcx.sess);
+            debug!("pretty printing THIR tree");
+            for did in tcx.body_owners() {
+                let hir = tcx.hir();
+                let body = hir.body(hir.body_owned_by(hir.local_def_id_to_hir_id(did)));
+                let arena = thir::Arena::default();
+                let thir =
+                    thir::build_thir(tcx, ty::WithOptConstParam::unknown(did), &arena, &body.value);
+                let _ = writeln!(out, "{:?}:\n{:#?}\n", did, thir);
+            }
+            out
+        }
+
         _ => unreachable!(),
     };
 
diff --git a/compiler/rustc_mir_build/src/build/mod.rs b/compiler/rustc_mir_build/src/build/mod.rs
index b633fe32674..9c83c0d09aa 100644
--- a/compiler/rustc_mir_build/src/build/mod.rs
+++ b/compiler/rustc_mir_build/src/build/mod.rs
@@ -1,7 +1,6 @@
 use crate::build;
 use crate::build::scope::DropKind;
-use crate::thir::cx::build_thir;
-use crate::thir::{Arena, BindingMode, Expr, LintLevel, Pat, PatKind};
+use crate::thir::{build_thir, Arena, BindingMode, Expr, LintLevel, Pat, PatKind};
 use rustc_attr::{self as attr, UnwindAttr};
 use rustc_errors::ErrorReported;
 use rustc_hir as hir;
diff --git a/compiler/rustc_mir_build/src/lib.rs b/compiler/rustc_mir_build/src/lib.rs
index 0866892265b..b1591d8ba35 100644
--- a/compiler/rustc_mir_build/src/lib.rs
+++ b/compiler/rustc_mir_build/src/lib.rs
@@ -20,7 +20,7 @@ extern crate rustc_middle;
 
 mod build;
 mod lints;
-mod thir;
+pub mod thir;
 
 use rustc_middle::ty::query::Providers;
 
diff --git a/compiler/rustc_mir_build/src/thir/cx/mod.rs b/compiler/rustc_mir_build/src/thir/cx/mod.rs
index 66c11ea9528..fe8a58c0088 100644
--- a/compiler/rustc_mir_build/src/thir/cx/mod.rs
+++ b/compiler/rustc_mir_build/src/thir/cx/mod.rs
@@ -14,7 +14,7 @@ use rustc_middle::middle::region;
 use rustc_middle::mir::interpret::{LitToConstError, LitToConstInput};
 use rustc_middle::ty::{self, Ty, TyCtxt};
 
-crate fn build_thir<'thir, 'tcx>(
+pub fn build_thir<'thir, 'tcx>(
     tcx: TyCtxt<'tcx>,
     owner_def: ty::WithOptConstParam<LocalDefId>,
     arena: &'thir Arena<'thir, 'tcx>,
diff --git a/compiler/rustc_mir_build/src/thir/mod.rs b/compiler/rustc_mir_build/src/thir/mod.rs
index 27a7e99951c..0c9df32c188 100644
--- a/compiler/rustc_mir_build/src/thir/mod.rs
+++ b/compiler/rustc_mir_build/src/thir/mod.rs
@@ -18,36 +18,37 @@ use rustc_target::abi::VariantIdx;
 use rustc_target::asm::InlineAsmRegOrRegClass;
 
 crate mod constant;
+
 crate mod cx;
+pub use cx::build_thir;
 
 crate mod pattern;
-crate use self::pattern::PatTyProj;
-crate use self::pattern::{BindingMode, FieldPat, Pat, PatKind, PatRange};
+pub use self::pattern::{Ascription, BindingMode, FieldPat, Pat, PatKind, PatRange, PatTyProj};
 
 mod arena;
-crate use arena::Arena;
+pub use arena::Arena;
 
 mod util;
 
 #[derive(Copy, Clone, Debug)]
-crate enum LintLevel {
+pub enum LintLevel {
     Inherited,
     Explicit(hir::HirId),
 }
 
 #[derive(Debug)]
-crate struct Block<'thir, 'tcx> {
-    crate targeted_by_break: bool,
-    crate region_scope: region::Scope,
-    crate opt_destruction_scope: Option<region::Scope>,
-    crate span: Span,
-    crate stmts: &'thir [Stmt<'thir, 'tcx>],
-    crate expr: Option<&'thir Expr<'thir, 'tcx>>,
-    crate safety_mode: BlockSafety,
+pub struct Block<'thir, 'tcx> {
+    pub targeted_by_break: bool,
+    pub region_scope: region::Scope,
+    pub opt_destruction_scope: Option<region::Scope>,
+    pub span: Span,
+    pub stmts: &'thir [Stmt<'thir, 'tcx>],
+    pub expr: Option<&'thir Expr<'thir, 'tcx>>,
+    pub safety_mode: BlockSafety,
 }
 
 #[derive(Copy, Clone, Debug)]
-crate enum BlockSafety {
+pub enum BlockSafety {
     Safe,
     ExplicitUnsafe(hir::HirId),
     PushUnsafe,
@@ -55,13 +56,13 @@ crate enum BlockSafety {
 }
 
 #[derive(Debug)]
-crate struct Stmt<'thir, 'tcx> {
-    crate kind: StmtKind<'thir, 'tcx>,
-    crate opt_destruction_scope: Option<region::Scope>,
+pub struct Stmt<'thir, 'tcx> {
+    pub kind: StmtKind<'thir, 'tcx>,
+    pub opt_destruction_scope: Option<region::Scope>,
 }
 
 #[derive(Debug)]
-crate enum StmtKind<'thir, 'tcx> {
+pub enum StmtKind<'thir, 'tcx> {
     Expr {
         /// scope for this statement; may be used as lifetime of temporaries
         scope: region::Scope,
@@ -111,23 +112,23 @@ rustc_data_structures::static_assert_size!(Expr<'_, '_>, 144);
 /// example, method calls and overloaded operators are absent: they are
 /// expected to be converted into `Expr::Call` instances.
 #[derive(Debug)]
-crate struct Expr<'thir, 'tcx> {
+pub struct Expr<'thir, 'tcx> {
     /// type of this expression
-    crate ty: Ty<'tcx>,
+    pub ty: Ty<'tcx>,
 
     /// lifetime of this expression if it should be spilled into a
     /// temporary; should be None only if in a constant context
-    crate temp_lifetime: Option<region::Scope>,
+    pub temp_lifetime: Option<region::Scope>,
 
     /// span of the expression in the source
-    crate span: Span,
+    pub span: Span,
 
     /// kind of expression
-    crate kind: ExprKind<'thir, 'tcx>,
+    pub kind: ExprKind<'thir, 'tcx>,
 }
 
 #[derive(Debug)]
-crate enum ExprKind<'thir, 'tcx> {
+pub enum ExprKind<'thir, 'tcx> {
     Scope {
         region_scope: region::Scope,
         lint_level: LintLevel,
@@ -316,41 +317,41 @@ crate enum ExprKind<'thir, 'tcx> {
 }
 
 #[derive(Debug)]
-crate struct FieldExpr<'thir, 'tcx> {
-    crate name: Field,
-    crate expr: &'thir Expr<'thir, 'tcx>,
+pub struct FieldExpr<'thir, 'tcx> {
+    pub name: Field,
+    pub expr: &'thir Expr<'thir, 'tcx>,
 }
 
 #[derive(Debug)]
-crate struct FruInfo<'thir, 'tcx> {
-    crate base: &'thir Expr<'thir, 'tcx>,
-    crate field_types: &'thir [Ty<'tcx>],
+pub struct FruInfo<'thir, 'tcx> {
+    pub base: &'thir Expr<'thir, 'tcx>,
+    pub field_types: &'thir [Ty<'tcx>],
 }
 
 #[derive(Debug)]
-crate struct Arm<'thir, 'tcx> {
-    crate pattern: Pat<'tcx>,
-    crate guard: Option<Guard<'thir, 'tcx>>,
-    crate body: &'thir Expr<'thir, 'tcx>,
-    crate lint_level: LintLevel,
-    crate scope: region::Scope,
-    crate span: Span,
+pub struct Arm<'thir, 'tcx> {
+    pub pattern: Pat<'tcx>,
+    pub guard: Option<Guard<'thir, 'tcx>>,
+    pub body: &'thir Expr<'thir, 'tcx>,
+    pub lint_level: LintLevel,
+    pub scope: region::Scope,
+    pub span: Span,
 }
 
 #[derive(Debug)]
-crate enum Guard<'thir, 'tcx> {
+pub enum Guard<'thir, 'tcx> {
     If(&'thir Expr<'thir, 'tcx>),
     IfLet(Pat<'tcx>, &'thir Expr<'thir, 'tcx>),
 }
 
 #[derive(Copy, Clone, Debug)]
-crate enum LogicalOp {
+pub enum LogicalOp {
     And,
     Or,
 }
 
 #[derive(Debug)]
-crate enum InlineAsmOperand<'thir, 'tcx> {
+pub enum InlineAsmOperand<'thir, 'tcx> {
     In {
         reg: InlineAsmRegOrRegClass,
         expr: &'thir Expr<'thir, 'tcx>,
diff --git a/compiler/rustc_mir_build/src/thir/pattern/mod.rs b/compiler/rustc_mir_build/src/thir/pattern/mod.rs
index 6e29e60b303..9ac79a37ac6 100644
--- a/compiler/rustc_mir_build/src/thir/pattern/mod.rs
+++ b/compiler/rustc_mir_build/src/thir/pattern/mod.rs
@@ -40,22 +40,22 @@ crate enum PatternError {
 }
 
 #[derive(Copy, Clone, Debug, PartialEq)]
-crate enum BindingMode {
+pub enum BindingMode {
     ByValue,
     ByRef(BorrowKind),
 }
 
 #[derive(Clone, Debug, PartialEq)]
-crate struct FieldPat<'tcx> {
-    crate field: Field,
-    crate pattern: Pat<'tcx>,
+pub struct FieldPat<'tcx> {
+    pub field: Field,
+    pub pattern: Pat<'tcx>,
 }
 
 #[derive(Clone, Debug, PartialEq)]
-crate struct Pat<'tcx> {
-    crate ty: Ty<'tcx>,
-    crate span: Span,
-    crate kind: Box<PatKind<'tcx>>,
+pub struct Pat<'tcx> {
+    pub ty: Ty<'tcx>,
+    pub span: Span,
+    pub kind: Box<PatKind<'tcx>>,
 }
 
 impl<'tcx> Pat<'tcx> {
@@ -65,8 +65,8 @@ impl<'tcx> Pat<'tcx> {
 }
 
 #[derive(Copy, Clone, Debug, PartialEq)]
-crate struct PatTyProj<'tcx> {
-    crate user_ty: CanonicalUserType<'tcx>,
+pub struct PatTyProj<'tcx> {
+    pub user_ty: CanonicalUserType<'tcx>,
 }
 
 impl<'tcx> PatTyProj<'tcx> {
@@ -92,8 +92,8 @@ impl<'tcx> PatTyProj<'tcx> {
 }
 
 #[derive(Copy, Clone, Debug, PartialEq)]
-crate struct Ascription<'tcx> {
-    crate user_ty: PatTyProj<'tcx>,
+pub struct Ascription<'tcx> {
+    pub user_ty: PatTyProj<'tcx>,
     /// Variance to use when relating the type `user_ty` to the **type of the value being
     /// matched**. Typically, this is `Variance::Covariant`, since the value being matched must
     /// have a type that is some subtype of the ascribed type.
@@ -112,12 +112,12 @@ crate struct Ascription<'tcx> {
     /// requires that `&'static str <: T_x`, where `T_x` is the type of `x`. Really, we should
     /// probably be checking for a `PartialEq` impl instead, but this preserves the behavior
     /// of the old type-check for now. See #57280 for details.
-    crate variance: ty::Variance,
-    crate user_ty_span: Span,
+    pub variance: ty::Variance,
+    pub user_ty_span: Span,
 }
 
 #[derive(Clone, Debug, PartialEq)]
-crate enum PatKind<'tcx> {
+pub enum PatKind<'tcx> {
     Wild,
 
     AscribeUserType {
@@ -195,10 +195,10 @@ crate enum PatKind<'tcx> {
 }
 
 #[derive(Copy, Clone, Debug, PartialEq)]
-crate struct PatRange<'tcx> {
-    crate lo: &'tcx ty::Const<'tcx>,
-    crate hi: &'tcx ty::Const<'tcx>,
-    crate end: RangeEnd,
+pub struct PatRange<'tcx> {
+    pub lo: &'tcx ty::Const<'tcx>,
+    pub hi: &'tcx ty::Const<'tcx>,
+    pub end: RangeEnd,
 }
 
 impl<'tcx> fmt::Display for Pat<'tcx> {
diff --git a/compiler/rustc_session/src/config.rs b/compiler/rustc_session/src/config.rs
index f25828e2161..c1be90efc72 100644
--- a/compiler/rustc_session/src/config.rs
+++ b/compiler/rustc_session/src/config.rs
@@ -2074,6 +2074,7 @@ fn parse_pretty(
             ("hir,identified", true) => Hir(PpHirMode::Identified),
             ("hir,typed", true) => Hir(PpHirMode::Typed),
             ("hir-tree", true) => HirTree,
+            ("thir-tree", true) => ThirTree,
             ("mir", true) => Mir,
             ("mir-cfg", true) => MirCFG,
             _ => {
@@ -2265,6 +2266,8 @@ pub enum PpMode {
     Hir(PpHirMode),
     /// `-Zunpretty=hir-tree`
     HirTree,
+    /// `-Zunpretty=thir-tree`
+    ThirTree,
     /// `-Zunpretty=mir`
     Mir,
     /// `-Zunpretty=mir-cfg`
@@ -2282,6 +2285,7 @@ impl PpMode {
             | AstTree(PpAstTreeMode::Expanded)
             | Hir(_)
             | HirTree
+            | ThirTree
             | Mir
             | MirCFG => true,
         }