Auto merge of #86251 - Smittyvb:thir-tree-again, r=oli-obk

Support -Z unpretty=thir-tree again

Currently `-Z unpretty=thir-tree` is broken after some THIR refactorings. This re-implements it, making it easier to debug THIR-related issues.

We have to do analyzes before getting the THIR, since trying to create THIR from invalid HIR can ICE. But doing those analyzes requires the THIR to be built and stolen. We work around this by creating a separate query to construct the THIR tree string representation.

Closes https://github.com/rust-lang/project-thir-unsafeck/issues/8, fixes #85552.

Cargo.lock

@@ -3726,6 +3726,7 @@ dependencies = [
  "rustc_session",
  "rustc_span",
  "rustc_target",
+ "rustc_typeck",
  "tracing",
  "tracing-subscriber",
  "tracing-tree",

compiler/rustc_driver/Cargo.toml

@@ -34,6 +34,7 @@ rustc_interface = { path = "../rustc_interface" }
 rustc_serialize = { path = "../rustc_serialize" }
 rustc_ast = { path = "../rustc_ast" }
 rustc_span = { path = "../rustc_span" }
+rustc_typeck = { path = "../rustc_typeck" }
 
 [target.'cfg(windows)'.dependencies]
 winapi = { version = "0.3", features = ["consoleapi", "debugapi", "processenv"] }

compiler/rustc_driver/src/pretty.rs

@@ -14,6 +14,7 @@
 use rustc_span::FileName;
 
 use std::cell::Cell;
+use std::fmt::Write;
 use std::path::Path;
 
 pub use self::PpMode::*;
@@ -471,7 +472,6 @@ fn print_with_analysis(
     ofile: Option<&Path>,
 ) -> Result<(), ErrorReported> {
     tcx.analysis(())?;
-
     let out = match ppm {
         Mir => {
             let mut out = Vec::new();
@@ -486,8 +486,18 @@ fn print_with_analysis(
         }
 
         ThirTree => {
-            // FIXME(rust-lang/project-thir-unsafeck#8)
+            let mut out = String::new();
-            todo!()
+            abort_on_err(rustc_typeck::check_crate(tcx), tcx.sess);
+            debug!("pretty printing THIR tree");
+            for did in tcx.body_owners() {
+                let _ = writeln!(
+                    out,
+                    "{:?}:\n{}\n",
+                    did,
+                    tcx.thir_tree(ty::WithOptConstParam::unknown(did))
+                );
+            }
+            out
         }
 
         _ => unreachable!(),

compiler/rustc_middle/src/query/mod.rs

@@ -230,6 +230,12 @@
         desc { |tcx| "building THIR for `{}`", tcx.def_path_str(key.did.to_def_id()) }
     }
 
+    /// Create a THIR tree for debugging.
+    query thir_tree(key: ty::WithOptConstParam<LocalDefId>) -> String {
+        no_hash
+        desc { |tcx| "constructing THIR tree for `{}`", tcx.def_path_str(key.did.to_def_id()) }
+    }
+
     /// Set of all the `DefId`s in this crate that have MIR associated with
     /// them. This includes all the body owners, but also things like struct
     /// constructors.

compiler/rustc_mir_build/src/lib.rs

@@ -30,4 +30,5 @@ pub fn provide(providers: &mut Providers) {
     providers.thir_check_unsafety = check_unsafety::thir_check_unsafety;
     providers.thir_check_unsafety_for_const_arg = check_unsafety::thir_check_unsafety_for_const_arg;
     providers.thir_body = thir::cx::thir_body;
+    providers.thir_tree = thir::cx::thir_tree;
 }

compiler/rustc_mir_build/src/thir/cx/mod.rs

@@ -30,6 +30,13 @@
     (tcx.alloc_steal_thir(cx.thir), expr)
 }
 
+crate fn thir_tree<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    owner_def: ty::WithOptConstParam<LocalDefId>,
+) -> String {
+    format!("{:#?}", thir_body(tcx, owner_def).0.steal())
+}
+
 struct Cx<'tcx> {
     tcx: TyCtxt<'tcx>,
     thir: Thir<'tcx>,

src/test/ui/thir-tree.rs

@@ -0,0 +1,4 @@
+// compile-flags: -Z unpretty=thir-tree
+// check-pass
+
+pub fn main() {}

src/test/ui/thir-tree.stdout

@@ -0,0 +1,55 @@
+DefId(0:3 ~ thir_tree[348d]::main):
+Thir {
+    arms: [],
+    exprs: [
+        Expr {
+            ty: (),
+            temp_lifetime: Some(
+                Node(2),
+            ),
+            span: $DIR/thir-tree.rs:4:15: 4:17 (#0),
+            kind: Block {
+                body: Block {
+                    targeted_by_break: false,
+                    region_scope: Node(1),
+                    opt_destruction_scope: None,
+                    span: $DIR/thir-tree.rs:4:15: 4:17 (#0),
+                    stmts: [],
+                    expr: None,
+                    safety_mode: Safe,
+                },
+            },
+        },
+        Expr {
+            ty: (),
+            temp_lifetime: Some(
+                Node(2),
+            ),
+            span: $DIR/thir-tree.rs:4:15: 4:17 (#0),
+            kind: Scope {
+                region_scope: Node(2),
+                lint_level: Explicit(
+                    HirId {
+                        owner: DefId(0:3 ~ thir_tree[348d]::main),
+                        local_id: 2,
+                    },
+                ),
+                value: e0,
+            },
+        },
+        Expr {
+            ty: (),
+            temp_lifetime: Some(
+                Node(2),
+            ),
+            span: $DIR/thir-tree.rs:4:15: 4:17 (#0),
+            kind: Scope {
+                region_scope: Destruction(2),
+                lint_level: Inherited,
+                value: e1,
+            },
+        },
+    ],
+    stmts: [],
+}
+