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.

Author: michaelwoerister

compiler/rustc_codegen_llvm/src/debuginfo/mod.rs

@@ -25,7 +25,7 @@ use rustc_data_structures::sync::Lrc;
 use rustc_hir::def_id::{DefId, DefIdMap};
 use rustc_index::vec::IndexVec;
 use rustc_middle::mir;
-use rustc_middle::ty::layout::{HasTyCtxt, LayoutOf};
+use rustc_middle::ty::layout::LayoutOf;
 use rustc_middle::ty::subst::{GenericArgKind, SubstsRef};
 use rustc_middle::ty::{self, Instance, ParamEnv, Ty, TypeFoldable};
 use rustc_session::config::{self, DebugInfo};
@@ -307,9 +307,11 @@ impl<'ll, 'tcx> DebugInfoMethods<'tcx> for CodegenCx<'ll, 'tcx> {
         fn_abi: &FnAbi<'tcx, Ty<'tcx>>,
         maybe_definition_llfn: Option<&'ll Value>,
     ) -> &'ll DIScope {
+        let tcx = self.tcx;
+
         let def_id = instance.def_id();
         let containing_scope = get_containing_scope(self, instance);
-        let span = self.tcx.def_span(def_id);
+        let span = tcx.def_span(def_id);
         let loc = self.lookup_debug_loc(span.lo());
         let file_metadata = file_metadata(self, &loc.file);
 
@@ -319,16 +321,24 @@ impl<'ll, 'tcx> DebugInfoMethods<'tcx> for CodegenCx<'ll, 'tcx> {
         };
 
         let mut name = String::new();
-        type_names::push_item_name(self.tcx(), def_id, false, &mut name);
+        type_names::push_item_name(tcx, def_id, false, &mut name);
 
         // Find the enclosing function, in case this is a closure.
-        let enclosing_fn_def_id = self.tcx().typeck_root_def_id(def_id);
+        let enclosing_fn_def_id = tcx.typeck_root_def_id(def_id);
+
+        // We look up the generics of the enclosing function and truncate the substs
+        // to their length in order to cut off extra stuff that might be in there for
+        // closures or generators.
+        let generics = tcx.generics_of(enclosing_fn_def_id);
+        let substs = instance.substs.truncate_to(tcx, generics);
+
+        type_names::push_generic_params(
+            tcx,
+            tcx.normalize_erasing_regions(ty::ParamEnv::reveal_all(), substs),
+            &mut name,
+        );
 
-        // Get_template_parameters() will append a `<...>` clause to the function
-        // name if necessary.
-        let generics = self.tcx().generics_of(enclosing_fn_def_id);
-        let substs = instance.substs.truncate_to(self.tcx(), generics);
-        let template_parameters = get_template_parameters(self, generics, substs, &mut name);
+        let template_parameters = get_template_parameters(self, generics, substs);
 
         let linkage_name = &mangled_name_of_instance(self, instance).name;
         // Omit the linkage_name if it is the same as subprogram name.
@@ -350,7 +360,7 @@ impl<'ll, 'tcx> DebugInfoMethods<'tcx> for CodegenCx<'ll, 'tcx> {
         if self.sess().opts.optimize != config::OptLevel::No {
             spflags |= DISPFlags::SPFlagOptimized;
         }
-        if let Some((id, _)) = self.tcx.entry_fn(()) {
+        if let Some((id, _)) = tcx.entry_fn(()) {
             if id == def_id {
                 spflags |= DISPFlags::SPFlagMainSubprogram;
             }
@@ -429,14 +439,7 @@ impl<'ll, 'tcx> DebugInfoMethods<'tcx> for CodegenCx<'ll, 'tcx> {
             cx: &CodegenCx<'ll, 'tcx>,
             generics: &ty::Generics,
             substs: SubstsRef<'tcx>,
-            name_to_append_suffix_to: &mut String,
         ) -> &'ll DIArray {
-            type_names::push_generic_params(
-                cx.tcx,
-                cx.tcx.normalize_erasing_regions(ty::ParamEnv::reveal_all(), substs),
-                name_to_append_suffix_to,
-            );
-
             if substs.types().next().is_none() {
                 return create_DIArray(DIB(cx), &[]);
             }

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>,

src/test/codegen/async-fn-debug-msvc.rs

@@ -17,7 +17,7 @@ async fn async_fn_test() {
 // FIXME: No way to reliably check the filename.
 
 // CHECK-DAG:  [[ASYNC_FN:!.*]] = !DINamespace(name: "async_fn_test"
-// CHECK-DAG:  [[GEN:!.*]] = !DICompositeType(tag: DW_TAG_union_type, name: "async_fn$0"
+// CHECK-DAG:  [[GEN:!.*]] = !DICompositeType(tag: DW_TAG_union_type, name: "async_fn_env$0"
 // CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, name: "variant0", scope: [[GEN]],
 // For brevity, we only check the struct name and members of the last variant.
 // CHECK-SAME: file: [[FILE:![0-9]*]], line: 11,

src/test/codegen/async-fn-debug.rs

@@ -17,7 +17,7 @@ async fn async_fn_test() {
 // FIXME: No way to reliably check the filename.
 
 // CHECK-DAG:  [[ASYNC_FN:!.*]] = !DINamespace(name: "async_fn_test"
-// CHECK-DAG:  [[GEN:!.*]] = !DICompositeType(tag: DW_TAG_structure_type, name: "{async_fn#0}", scope: [[ASYNC_FN]]
+// CHECK-DAG:  [[GEN:!.*]] = !DICompositeType(tag: DW_TAG_structure_type, name: "{async_fn_env#0}", scope: [[ASYNC_FN]]
 // CHECK:      [[VARIANT:!.*]] = !DICompositeType(tag: DW_TAG_variant_part, scope: [[ASYNC_FN]],
 // CHECK-NOT:  flags: DIFlagArtificial
 // CHECK-SAME: discriminator: [[DISC:![0-9]*]]

src/test/codegen/debug-vtable.rs

@@ -1,25 +1,36 @@
-// compile-flags: -Cdebuginfo=2 -Copt-level=0 -Ccodegen-units=1
-// ignore-tidy-linelength
-
 // This test checks the debuginfo for the expected 3 vtables is generated for correct names and number
 // of entries.
 
-// NONMSVC-LABEL: !DIGlobalVariable(name: "<debug_vtable::Foo as debug_vtable::SomeTrait>::{vtable}"
-// MSVC-LABEL: !DIGlobalVariable(name: "impl$<debug_vtable::Foo, debug_vtable::SomeTrait>::vtable$"
+// Use the v0 symbol mangling scheme to codegen order independent of rustc version.
+// Unnamed items like shims are generated in lexicographical order of their symbol name and in the
+// legacy mangling scheme rustc version and generic parameters are both hashed into a single part
+// of the name, thus randomizing item order with respect to rustc version.
+
+// compile-flags: -Cdebuginfo=2 -Copt-level=0 -Csymbol-mangling-version=v0
+// ignore-tidy-linelength
+
+// NONMSVC: !DIGlobalVariable(name: "<debug_vtable::Foo as debug_vtable::SomeTrait>::{vtable}"
+// MSVC: !DIGlobalVariable(name: "impl$<debug_vtable::Foo, debug_vtable::SomeTrait>::vtable$"
 // NONMSVC: !DIDerivedType(tag: DW_TAG_pointer_type, name: "*const ()",
 // MSVC: !DIDerivedType(tag: DW_TAG_pointer_type, name: "ptr_const$<tuple$<> >",
 // CHECK: !DISubrange(count: 5
 
-// NONMSVC-LABEL: !DIGlobalVariable(name: "<debug_vtable::Foo as debug_vtable::SomeTraitWithGenerics<u64, i8>>::{vtable}"
-// MSVC-LABEL: !DIGlobalVariable(name: "impl$<debug_vtable::Foo, debug_vtable::SomeTraitWithGenerics<u64,i8> >::vtable$"
+// NONMSVC: !DIGlobalVariable(name: "<debug_vtable::Foo as debug_vtable::SomeTraitWithGenerics<u64, i8>>::{vtable}"
+// MSVC: !DIGlobalVariable(name: "impl$<debug_vtable::Foo, debug_vtable::SomeTraitWithGenerics<u64,i8> >::vtable$"
 // CHECK: !DISubrange(count: 4
 
-// NONMSVC-LABEL: !DIGlobalVariable(name: "<debug_vtable::Foo as _>::{vtable}"
-// MSVC-LABEL: !DIGlobalVariable(name: "impl$<debug_vtable::Foo, _>::vtable$"
+// NONMSVC: !DIGlobalVariable(name: "<debug_vtable::Foo as _>::{vtable}"
+// MSVC: !DIGlobalVariable(name: "impl$<debug_vtable::Foo, _>::vtable$"
 // CHECK: !DISubrange(count: 3
 
-// NONMSVC-LABEL: !DIGlobalVariable(name: "<debug_vtable::bar::{closure#0} as core::ops::function::FnOnce<(core::option::Option<&dyn core::ops::function::Fn<(), Output=()>>)>>::{vtable}"
-// MSVC-LABEL: !DIGlobalVariable(name: "impl$<debug_vtable::bar::closure$0, core::ops::function::FnOnce<tuple$<enum$<core::option::Option<ref$<dyn$<core::ops::function::Fn<tuple$<>,assoc$<Output,tuple$<> > > > > >, {{.*}}, {{.*}}, Some> > > >::vtable$"
+// NONMSVC: !DIGlobalVariable(name: "<debug_vtable::bar::{closure_env#0} as core::ops::function::FnOnce<(core::option::Option<&dyn core::ops::function::Fn<(), Output=()>>)>>::{vtable}"
+// MSVC: !DIGlobalVariable(name: "impl$<debug_vtable::bar::closure_env$0, core::ops::function::FnOnce<tuple$<enum$<core::option::Option<ref$<dyn$<core::ops::function::Fn<tuple$<>,assoc$<Output,tuple$<> > > > > >, {{.*}}, {{.*}}, Some> > > >::vtable$"
+
+// NONMSVC: !DIGlobalVariable(name: "<debug_vtable::generic_closure::{closure_env#0}<bool> as core::ops::function::FnOnce<()>>::{vtable}"
+// MSVC: !DIGlobalVariable(name: "impl$<debug_vtable::generic_closure::closure_env$0<bool>, core::ops::function::FnOnce<tuple$<> > >::vtable$
+
+// NONMSVC: !DIGlobalVariable(name: "<debug_vtable::generic_closure::{closure_env#0}<u32> as core::ops::function::FnOnce<()>>::{vtable}"
+// MSVC: !DIGlobalVariable(name: "impl$<debug_vtable::generic_closure::closure_env$0<u32>, core::ops::function::FnOnce<tuple$<> > >::vtable$
 
 #![crate_type = "lib"]
 
@@ -31,16 +42,22 @@ pub trait SomeTrait {
 }
 
 impl SomeTrait for Foo {
-    fn method1(&self) -> u32 { 1 }
-    fn method2(&self) -> u32 { 2 }
+    fn method1(&self) -> u32 {
+        1
+    }
+    fn method2(&self) -> u32 {
+        2
+    }
 }
 
 pub trait SomeTraitWithGenerics<T, U> {
     fn method1(&self) -> (T, U);
 }
 
 impl SomeTraitWithGenerics<u64, i8> for Foo {
-    fn method1(&self) -> (u64, i8) { (1, 2) }
+    fn method1(&self) -> (u64, i8) {
+        (1, 2)
+    }
 }
 
 pub fn foo(x: &Foo) -> (u32, (u64, i8), &dyn Send) {
@@ -55,3 +72,11 @@ pub fn foo(x: &Foo) -> (u32, (u64, i8), &dyn Send) {
 pub fn bar() -> Box<dyn FnOnce(Option<&dyn Fn()>)> {
     Box::new(|_x: Option<&dyn Fn()>| {})
 }
+
+fn generic_closure<T: 'static>(x: T) -> Box<dyn FnOnce() -> T> {
+    Box::new(move || x)
+}
+
+pub fn instantiate_generic_closures() -> (Box<dyn FnOnce() -> u32>, Box<dyn FnOnce() -> bool>) {
+    (generic_closure(1u32), generic_closure(false))
+}