debuginfo: Make sure that type names for closure and generator environments are unique in debuginfo.

Before this change, closure/generator environments coming from different
instantiations of the same generic function were all assigned the same
name even though they were distinct types with potentially different data
layout. Now we append the generic arguments of the originating function
to the type name.

This commit also emits '{closure_env#0}' as the name of these types in
order to disambiguate them from the accompanying closure function
'{closure#0}'. Previously both were assigned the same name.

1 files changed, 74 insertions, 36 deletions

diff --git a/compiler/rustc_codegen_ssa/src/debuginfo/type_names.rs b/compiler/rustc_codegen_ssa/src/debuginfo/type_names.rs
index 9687fd09a53..831c34d8f1f 100644
--- a/compiler/rustc_codegen_ssa/src/debuginfo/type_names.rs
+++ b/compiler/rustc_codegen_ssa/src/debuginfo/type_names.rs
@@ -13,9 +13,9 @@
 
 use rustc_data_structures::fx::FxHashSet;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
-use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
 use rustc_hir::definitions::{DefPathData, DefPathDataName, DisambiguatedDefPathData};
+use rustc_hir::{AsyncGeneratorKind, GeneratorKind, Mutability};
 use rustc_middle::ty::layout::IntegerExt;
 use rustc_middle::ty::subst::{GenericArgKind, SubstsRef};
 use rustc_middle::ty::{self, AdtDef, ExistentialProjection, Ty, TyCtxt};
@@ -102,14 +102,14 @@ fn push_debuginfo_type_name<'tcx>(
         ty::RawPtr(ty::TypeAndMut { ty: inner_type, mutbl }) => {
             if cpp_like_debuginfo {
                 match mutbl {
-                    hir::Mutability::Not => output.push_str("ptr_const$<"),
-                    hir::Mutability::Mut => output.push_str("ptr_mut$<"),
+                    Mutability::Not => output.push_str("ptr_const$<"),
+                    Mutability::Mut => output.push_str("ptr_mut$<"),
                 }
             } else {
                 output.push('*');
                 match mutbl {
-                    hir::Mutability::Not => output.push_str("const "),
-                    hir::Mutability::Mut => output.push_str("mut "),
+                    Mutability::Not => output.push_str("const "),
+                    Mutability::Mut => output.push_str("mut "),
                 }
             }
 
@@ -131,8 +131,8 @@ fn push_debuginfo_type_name<'tcx>(
                 output.push_str(mutbl.prefix_str());
             } else if !is_slice_or_str {
                 match mutbl {
-                    hir::Mutability::Not => output.push_str("ref$<"),
-                    hir::Mutability::Mut => output.push_str("ref_mut$<"),
+                    Mutability::Not => output.push_str("ref$<"),
+                    Mutability::Mut => output.push_str("ref_mut$<"),
                 }
             }
 
@@ -345,14 +345,39 @@ fn push_debuginfo_type_name<'tcx>(
             // processing
             visited.remove(t);
         }
-        ty::Closure(def_id, ..) | ty::Generator(def_id, ..) => {
-            let key = tcx.def_key(def_id);
+        ty::Closure(def_id, substs) | ty::Generator(def_id, substs, ..) => {
+            // Name will be "{closure_env#0}<T1, T2, ...>", "{generator_env#0}<T1, T2, ...>", or
+            // "{async_fn_env#0}<T1, T2, ...>", etc.
+            let def_key = tcx.def_key(def_id);
+
             if qualified {
-                let parent_def_id = DefId { index: key.parent.unwrap(), ..def_id };
+                let parent_def_id = DefId { index: def_key.parent.unwrap(), ..def_id };
                 push_item_name(tcx, parent_def_id, true, output);
                 output.push_str("::");
             }
-            push_unqualified_item_name(tcx, def_id, key.disambiguated_data, output);
+
+            let mut label = String::with_capacity(20);
+            write!(&mut label, "{}_env", generator_kind_label(tcx.generator_kind(def_id))).unwrap();
+
+            push_disambiguated_special_name(
+                &label,
+                def_key.disambiguated_data.disambiguator,
+                cpp_like_debuginfo,
+                output,
+            );
+
+            // We also need to add the generic arguments of the async fn/generator or
+            // the enclosing function (for closures or async blocks), so that we end
+            // up with a unique name for every instantiation.
+
+            // Find the generics of the enclosing function, as defined in the source code.
+            let enclosing_fn_def_id = tcx.typeck_root_def_id(def_id);
+            let generics = tcx.generics_of(enclosing_fn_def_id);
+
+            // Truncate the substs to the length of the above generics. This will cut off
+            // anything closure- or generator-specific.
+            let substs = substs.truncate_to(tcx, generics);
+            push_generic_params_internal(tcx, substs, output, visited);
         }
         // Type parameters from polymorphized functions.
         ty::Param(_) => {
@@ -509,6 +534,29 @@ pub fn push_item_name(tcx: TyCtxt<'_>, def_id: DefId, qualified: bool, output: &
     push_unqualified_item_name(tcx, def_id, def_key.disambiguated_data, output);
 }
 
+fn generator_kind_label(generator_kind: Option<GeneratorKind>) -> &'static str {
+    match generator_kind {
+        Some(GeneratorKind::Async(AsyncGeneratorKind::Block)) => "async_block",
+        Some(GeneratorKind::Async(AsyncGeneratorKind::Closure)) => "async_closure",
+        Some(GeneratorKind::Async(AsyncGeneratorKind::Fn)) => "async_fn",
+        Some(GeneratorKind::Gen) => "generator",
+        None => "closure",
+    }
+}
+
+fn push_disambiguated_special_name(
+    label: &str,
+    disambiguator: u32,
+    cpp_like_debuginfo: bool,
+    output: &mut String,
+) {
+    if cpp_like_debuginfo {
+        write!(output, "{}${}", label, disambiguator).unwrap();
+    } else {
+        write!(output, "{{{}#{}}}", label, disambiguator).unwrap();
+    }
+}
+
 fn push_unqualified_item_name(
     tcx: TyCtxt<'_>,
     def_id: DefId,
@@ -519,42 +567,32 @@ fn push_unqualified_item_name(
         DefPathData::CrateRoot => {
             output.push_str(tcx.crate_name(def_id.krate).as_str());
         }
-        DefPathData::ClosureExpr if tcx.generator_kind(def_id).is_some() => {
-            let key = match tcx.generator_kind(def_id).unwrap() {
-                hir::GeneratorKind::Async(hir::AsyncGeneratorKind::Block) => "async_block",
-                hir::GeneratorKind::Async(hir::AsyncGeneratorKind::Closure) => "async_closure",
-                hir::GeneratorKind::Async(hir::AsyncGeneratorKind::Fn) => "async_fn",
-                hir::GeneratorKind::Gen => "generator",
-            };
-            // Generators look like closures, but we want to treat them differently
-            // in the debug info.
-            if cpp_like_debuginfo(tcx) {
-                write!(output, "{}${}", key, disambiguated_data.disambiguator).unwrap();
-            } else {
-                write!(output, "{{{}#{}}}", key, disambiguated_data.disambiguator).unwrap();
-            }
+        DefPathData::ClosureExpr => {
+            let label = generator_kind_label(tcx.generator_kind(def_id));
+
+            push_disambiguated_special_name(
+                label,
+                disambiguated_data.disambiguator,
+                cpp_like_debuginfo(tcx),
+                output,
+            );
         }
         _ => match disambiguated_data.data.name() {
             DefPathDataName::Named(name) => {
                 output.push_str(name.as_str());
             }
             DefPathDataName::Anon { namespace } => {
-                if cpp_like_debuginfo(tcx) {
-                    write!(output, "{}${}", namespace, disambiguated_data.disambiguator).unwrap();
-                } else {
-                    write!(output, "{{{}#{}}}", namespace, disambiguated_data.disambiguator)
-                        .unwrap();
-                }
+                push_disambiguated_special_name(
+                    namespace.as_str(),
+                    disambiguated_data.disambiguator,
+                    cpp_like_debuginfo(tcx),
+                    output,
+                );
             }
         },
     };
 }
 
-// Pushes the generic parameters in the given `InternalSubsts` to the output string.
-// This ignores region parameters, since they can't reliably be
-// reconstructed for items from non-local crates. For local crates, this
-// would be possible but with inlining and LTO we have to use the least
-// common denominator - otherwise we would run into conflicts.
 fn push_generic_params_internal<'tcx>(
     tcx: TyCtxt<'tcx>,
     substs: SubstsRef<'tcx>,