Auto merge of #103691 - michaelwoerister:consistent-slice-and-str-cpp-like-debuginfo-names, r=wesleywiser

[debuginfo] Make cpp-like debuginfo type names for slices and str consistent.

Before this PR, the compiler would emit the debuginfo name `slice$<T>` for all kinds of slices, regardless of whether they are behind a reference or not and regardless of the kind of reference. As a consequence, the types `Foo<&[T]>`, `Foo<[T]>`, and `Foo<&mut [T]>` would end up with the same type name `Foo<slice$<T> >` in debuginfo, making it impossible to disambiguate between them by name. Similarly, `&str` would get the name `str` in debuginfo, so the debuginfo name for `Foo<str>` and `Foo<&str>` would be the same. In contrast, `*const [bool]` and `*mut [bool]` would be `ptr_const$<slice$<bool> >` and `ptr_mut$<slice$<bool> >`, i.e. the encoding does not lose information about the type.

This PR removes all special handling for slices and `str`. The types `&[bool]`, `&mut [bool]`, and `&str` thus get the names `ref$<slice2$<bool> >`, `ref_mut$<slice2$<bool> >`, and `ref$<str$>` respectively -- as one would expect.

The new special name for slices is `slice2$` to differentiate it from the previous name `slice$`, which has different semantics. The same is true for `str` and `str$`. This kind of versioning already has a precedent with the case of `enum$` and `enum2$` and hopefully will make it easier to transition existing consumers of these names.

cc `@rust-lang/wg-debugging` `@vadimcn`

r? `@wesleywiser`

UPDATE: Here is a table to clarify the changes

| Rust type | DWARF name | C++-like name (before) | C++-like name (after) |
|-----------|------------|------------------------|------------------------|
| `[T]`        | `[T]`        | `slice$<T>`              | `slice2$<T>`           |
| `&[T]`       | `&[T]`       | `slice$<T>`              | `ref$<slice2$<T> >`    |
| `&mut [T]`   | `&mut [T]`   | `slice$<T>`              | `ref_mut$<slice2$<T> >`|
| `str`        | `str`        | `str`                    | `str$`           |
| `&str`       | `&str`       | `str`                    | `ref$<str$>`    |
| `&mut str`   | `&mut str`   | `str`                    | `ref_mut$<str$>`|
| `*const [T]` | `*const [T]` | `ptr_const$<slice$<T> >` | `ptr_const$<slice2$<T> >` |
| `*mut [T]`   | `*mut [T]`   | `ptr_mut$<slice$<T> >`   | `ptr_mut$<slice2$<T> >` |

As you can see, before the PR many types would end up with the same name, making it impossible to distinguish between them in NatVis or other places where types are matched or looked up by name. The DWARF version of names is not changed.

11 files changed, 56 insertions, 48 deletions

diff --git a/compiler/rustc_codegen_ssa/src/debuginfo/type_names.rs b/compiler/rustc_codegen_ssa/src/debuginfo/type_names.rs
index e05646e1e86..8647fbace2a 100644
--- a/compiler/rustc_codegen_ssa/src/debuginfo/type_names.rs
+++ b/compiler/rustc_codegen_ssa/src/debuginfo/type_names.rs
@@ -59,7 +59,13 @@ fn push_debuginfo_type_name<'tcx>(
     match *t.kind() {
         ty::Bool => output.push_str("bool"),
         ty::Char => output.push_str("char"),
-        ty::Str => output.push_str("str"),
+        ty::Str => {
+            if cpp_like_debuginfo {
+                output.push_str("str$")
+            } else {
+                output.push_str("str")
+            }
+        }
         ty::Never => {
             if cpp_like_debuginfo {
                 output.push_str("never$");
@@ -152,25 +158,19 @@ fn push_debuginfo_type_name<'tcx>(
             }
         }
         ty::Ref(_, inner_type, mutbl) => {
-            // Slices and `&str` are treated like C++ pointers when computing debug
-            // info for MSVC debugger. However, wrapping these types' names in a synthetic type
-            // causes the .natvis engine for WinDbg to fail to display their data, so we opt these
-            // types out to aid debugging in MSVC.
-            let is_slice_or_str = matches!(*inner_type.kind(), ty::Slice(_) | ty::Str);
-
-            if !cpp_like_debuginfo {
-                output.push('&');
-                output.push_str(mutbl.prefix_str());
-            } else if !is_slice_or_str {
+            if cpp_like_debuginfo {
                 match mutbl {
                     Mutability::Not => output.push_str("ref$<"),
                     Mutability::Mut => output.push_str("ref_mut$<"),
                 }
+            } else {
+                output.push('&');
+                output.push_str(mutbl.prefix_str());
             }
 
             push_debuginfo_type_name(tcx, inner_type, qualified, output, visited);
 
-            if cpp_like_debuginfo && !is_slice_or_str {
+            if cpp_like_debuginfo {
                 push_close_angle_bracket(cpp_like_debuginfo, output);
             }
         }
@@ -195,7 +195,7 @@ fn push_debuginfo_type_name<'tcx>(
         }
         ty::Slice(inner_type) => {
             if cpp_like_debuginfo {
-                output.push_str("slice$<");
+                output.push_str("slice2$<");
             } else {
                 output.push('[');
             }
diff --git a/src/etc/natvis/intrinsic.natvis b/src/etc/natvis/intrinsic.natvis
index 277e57aaf6f..8c16a562e34 100644
--- a/src/etc/natvis/intrinsic.natvis
+++ b/src/etc/natvis/intrinsic.natvis
@@ -1,6 +1,10 @@
 <?xml version="1.0" encoding="utf-8"?>
 <AutoVisualizer xmlns="http://schemas.microsoft.com/vstudio/debugger/natvis/2010">
-  <Type Name="str">
+  <Type Name="ref$&lt;str$&gt;">
+    <AlternativeType Name="ref_mut$&lt;str$&gt;" />
+    <AlternativeType Name="ptr_const$&lt;str$&gt;" />
+    <AlternativeType Name="ptr_mut$&lt;str$&gt;" />
+
     <DisplayString>{(char*)data_ptr,[length]s8}</DisplayString>
     <StringView>(char*)data_ptr,[length]s8</StringView>
     <Expand>
@@ -15,7 +19,11 @@
       </Synthetic>
     </Expand>
   </Type>
-  <Type Name="slice$&lt;*&gt;">
+  <Type Name="ref$&lt;slice2$&lt;*&gt; &gt;">
+    <AlternativeType Name="ref_mut$&lt;slice2$&lt;*&gt; &gt;" />
+    <AlternativeType Name="ptr_const$&lt;slice2$&lt;*&gt; &gt;" />
+    <AlternativeType Name="ptr_mut$&lt;slice2$&lt;*&gt; &gt;" />
+
     <DisplayString>{{ len={length} }}</DisplayString>
     <Expand>
       <Item Name="[len]" ExcludeView="simple">length</Item>
diff --git a/src/etc/natvis/liballoc.natvis b/src/etc/natvis/liballoc.natvis
index bf6c02b9146..41f4a3767f5 100644
--- a/src/etc/natvis/liballoc.natvis
+++ b/src/etc/natvis/liballoc.natvis
@@ -85,7 +85,7 @@
   </Type>
 
   <!-- alloc::rc::Rc<[T]> -->
-  <Type Name="alloc::rc::Rc&lt;slice$&lt;*&gt; &gt;">
+  <Type Name="alloc::rc::Rc&lt;slice2$&lt;*&gt; &gt;">
     <DisplayString>{{ len={ptr.pointer.length} }}</DisplayString>
     <Expand>
       <Item Name="[Length]" ExcludeView="simple">ptr.pointer.length</Item>
@@ -115,7 +115,7 @@
   </Type>
 
   <!-- alloc::rc::Weak<[T]> -->
-  <Type Name="alloc::rc::Weak&lt;slice$&lt;*&gt; &gt;">
+  <Type Name="alloc::rc::Weak&lt;slice2$&lt;*&gt; &gt;">
     <DisplayString>{{ len={ptr.pointer.length} }}</DisplayString>
     <Expand>
       <Item Name="[Length]" ExcludeView="simple">ptr.pointer.length</Item>
@@ -144,7 +144,7 @@
   </Type>
 
   <!-- alloc::sync::Arc<[T]> -->
-  <Type Name="alloc::sync::Arc&lt;slice$&lt;*&gt; &gt;">
+  <Type Name="alloc::sync::Arc&lt;slice2$&lt;*&gt; &gt;">
     <DisplayString>{{ len={ptr.pointer.length} }}</DisplayString>
     <Expand>
       <Item Name="[Length]" ExcludeView="simple">ptr.pointer.length</Item>
@@ -173,7 +173,7 @@
   </Type>
 
   <!-- alloc::sync::Weak<[T]> -->
-  <Type Name="alloc::sync::Weak&lt;slice$&lt;*&gt; &gt;">
+  <Type Name="alloc::sync::Weak&lt;slice2$&lt;*&gt; &gt;">
     <DisplayString>{{ len={ptr.pointer.length} }}</DisplayString>
     <Expand>
       <Item Name="[Length]" ExcludeView="simple">ptr.pointer.length</Item>
diff --git a/src/test/debuginfo/basic-types.rs b/src/test/debuginfo/basic-types.rs
index 07d33be2a07..9e82f071469 100644
--- a/src/test/debuginfo/basic-types.rs
+++ b/src/test/debuginfo/basic-types.rs
@@ -47,7 +47,6 @@
 // gdbg-check:$15 = {data_ptr = [...] "Hello, World!", length = 13}
 // gdbr-check:$15 = "Hello, World!"
 
-
 // === LLDB TESTS ==================================================================================
 
 // lldb-command:run
@@ -96,7 +95,6 @@
 // lldbg-check:[...]$12 = 3.5
 // lldbr-check:(f64) f64 = 3.5
 
-
 // === CDB TESTS ===================================================================================
 
 // cdb-command:g
@@ -131,7 +129,7 @@
 // cdb-command:.enable_unicode 1
 // FIXME(#88840): The latest version of the Windows SDK broke the visualizer for str.
 // cdb-command:dx  s
-// cdb-check:s                : [...] [Type: str]
+// cdb-check:s                : [...] [Type: ref$<str$>]
 
 #![allow(unused_variables)]
 #![feature(omit_gdb_pretty_printer_section)]
@@ -156,4 +154,6 @@ fn main() {
     _zzz(); // #break
 }
 
-fn _zzz() {()}
+fn _zzz() {
+    ()
+}
diff --git a/src/test/debuginfo/msvc-pretty-enums.rs b/src/test/debuginfo/msvc-pretty-enums.rs
index 7f1be6f2784..d66e4c660f7 100644
--- a/src/test/debuginfo/msvc-pretty-enums.rs
+++ b/src/test/debuginfo/msvc-pretty-enums.rs
@@ -116,13 +116,13 @@
 // cdb-check: niche_w_fields_3_niche5,d : F [Type: enum2$<msvc_pretty_enums::NicheLayoutWithFields3>]
 
 // cdb-command: dx -r3 niche_w_fields_std_result_ok,d
-// cdb-check: niche_w_fields_std_result_ok,d : Ok [Type: enum2$<core::result::Result<alloc::boxed::Box<slice$<u8>,alloc::alloc::Global>,u64> >]
-// cdb-check:    [+0x[...]] __0              [Type: alloc::boxed::Box<slice$<u8>,alloc::alloc::Global>]
+// cdb-check: niche_w_fields_std_result_ok,d : Ok [Type: enum2$<core::result::Result<alloc::boxed::Box<slice2$<u8>,alloc::alloc::Global>,u64> >]
+// cdb-check:    [+0x[...]] __0              [Type: alloc::boxed::Box<slice2$<u8>,alloc::alloc::Global>]
 // cdb-check:        [+0x[...]] data_ptr         : [...]
 // cdb-check:        [+0x[...]] length           : 3 [...]
 
 // cdb-command: dx -r3 niche_w_fields_std_result_err,d
-// cdb-check: niche_w_fields_std_result_err,d : Err [Type: enum2$<core::result::Result<alloc::boxed::Box<slice$<u8>,alloc::alloc::Global>,u64> >]
+// cdb-check: niche_w_fields_std_result_err,d : Err [Type: enum2$<core::result::Result<alloc::boxed::Box<slice2$<u8>,alloc::alloc::Global>,u64> >]
 // cdb-check:    [+0x[...]] __0              : 789 [Type: unsigned __int64]
 
 // cdb-command: dx -r2 arbitrary_discr1,d
diff --git a/src/test/debuginfo/msvc-scalarpair-params.rs b/src/test/debuginfo/msvc-scalarpair-params.rs
index 9630952cbaa..ae67f698151 100644
--- a/src/test/debuginfo/msvc-scalarpair-params.rs
+++ b/src/test/debuginfo/msvc-scalarpair-params.rs
@@ -38,14 +38,14 @@
 // cdb-command: g
 
 // cdb-command: dx s
-// cdb-check:s                : "this is a static str" [Type: str]
+// cdb-check:s                : "this is a static str" [Type: ref$<str$>]
 // cdb-check:    [len]            : 0x14 [Type: unsigned [...]]
 // cdb-check:    [chars]
 
 // cdb-command: g
 
 // cdb-command: dx s
-// cdb-check:s                : { len=0x5 } [Type: slice$<u8>]
+// cdb-check:s                : { len=0x5 } [Type: ref$<slice2$<u8> >]
 // cdb-check:    [len]            : 0x5 [Type: unsigned [...]]
 // cdb-check:    [0]              : 0x1 [Type: unsigned char]
 // cdb-check:    [1]              : 0x2 [Type: unsigned char]
diff --git a/src/test/debuginfo/pretty-std.rs b/src/test/debuginfo/pretty-std.rs
index a51b37205e8..d8c6344e0b6 100644
--- a/src/test/debuginfo/pretty-std.rs
+++ b/src/test/debuginfo/pretty-std.rs
@@ -69,7 +69,7 @@
 // cdb-command: g
 
 // cdb-command: dx slice,d
-// cdb-check:slice,d          : { len=4 } [Type: slice$<i32>]
+// cdb-check:slice,d          : { len=4 } [Type: ref$<slice2$<i32> >]
 // cdb-check:    [len]            : 4 [Type: [...]]
 // cdb-check:    [0]              : 0 [Type: int]
 // cdb-check:    [1]              : 1 [Type: int]
@@ -86,7 +86,7 @@
 // cdb-check:    [3]              : 7 [Type: unsigned __int64]
 
 // cdb-command: dx str_slice
-// cdb-check:str_slice        : "IAMA string slice!" [Type: str]
+// cdb-check:str_slice        : "IAMA string slice!" [Type: ref$<str$>]
 
 // cdb-command: dx string
 // cdb-check:string           : "IAMA string!" [Type: [...]::String]
diff --git a/src/test/debuginfo/rc_arc.rs b/src/test/debuginfo/rc_arc.rs
index c05c565d956..5d5492d7217 100644
--- a/src/test/debuginfo/rc_arc.rs
+++ b/src/test/debuginfo/rc_arc.rs
@@ -57,7 +57,7 @@
 // cdb-check:    [Weak reference count] : 2 [Type: core::cell::Cell<usize>]
 
 // cdb-command:dx slice_rc,d
-// cdb-check:slice_rc,d       : { len=3 } [Type: alloc::rc::Rc<slice$<u32> >]
+// cdb-check:slice_rc,d       : { len=3 } [Type: alloc::rc::Rc<slice2$<u32> >]
 // cdb-check:    [Length]         : 3 [Type: [...]]
 // cdb-check:    [Reference count] : 41 [Type: core::cell::Cell<usize>]
 // cdb-check:    [Weak reference count] : 2 [Type: core::cell::Cell<usize>]
@@ -66,7 +66,7 @@
 // cdb-check:    [2]              : 3 [Type: u32]
 
 // cdb-command:dx slice_rc_weak,d
-// cdb-check:slice_rc_weak,d  : { len=3 } [Type: alloc::rc::Weak<slice$<u32> >]
+// cdb-check:slice_rc_weak,d  : { len=3 } [Type: alloc::rc::Weak<slice2$<u32> >]
 // cdb-check:    [Length]         : 3 [Type: [...]]
 // cdb-check:    [Reference count] : 41 [Type: core::cell::Cell<usize>]
 // cdb-check:    [Weak reference count] : 2 [Type: core::cell::Cell<usize>]
@@ -85,7 +85,7 @@
 // cdb-check:    [Weak reference count] : 2 [Type: core::sync::atomic::AtomicUsize]
 
 // cdb-command:dx slice_arc,d
-// cdb-check:slice_arc,d      : { len=3 } [Type: alloc::sync::Arc<slice$<u32> >]
+// cdb-check:slice_arc,d      : { len=3 } [Type: alloc::sync::Arc<slice2$<u32> >]
 // cdb-check:    [Length]         : 3 [Type: [...]]
 // cdb-check:    [Reference count] : 61 [Type: core::sync::atomic::AtomicUsize]
 // cdb-check:    [Weak reference count] : 2 [Type: core::sync::atomic::AtomicUsize]
@@ -94,7 +94,7 @@
 // cdb-check:    [2]              : 6 [Type: u32]
 
 // cdb-command:dx slice_arc_weak,d
-// cdb-check:slice_arc_weak,d : { len=3 } [Type: alloc::sync::Weak<slice$<u32> >]
+// cdb-check:slice_arc_weak,d : { len=3 } [Type: alloc::sync::Weak<slice2$<u32> >]
 // cdb-check:    [Length]         : 3 [Type: [...]]
 // cdb-check:    [Reference count] : 61 [Type: core::sync::atomic::AtomicUsize]
 // cdb-check:    [Weak reference count] : 2 [Type: core::sync::atomic::AtomicUsize]
diff --git a/src/test/debuginfo/result-types.rs b/src/test/debuginfo/result-types.rs
index cdac47a784d..f1944fa38d2 100644
--- a/src/test/debuginfo/result-types.rs
+++ b/src/test/debuginfo/result-types.rs
@@ -7,12 +7,12 @@
 // cdb-command: g
 
 // cdb-command: dx x,d
-// cdb-check:x,d              : Ok [Type: enum2$<core::result::Result<i32,str> >]
+// cdb-check:x,d              : Ok [Type: enum2$<core::result::Result<i32,ref$<str$> > >]
 // cdb-check:    [...] __0              : -3 [Type: int]
 
 // cdb-command: dx y
-// cdb-check:y                : Err [Type: enum2$<core::result::Result<i32,str> >]
-// cdb-check:    [...] __0              : "Some error message" [Type: str]
+// cdb-check:y                : Err [Type: enum2$<core::result::Result<i32,ref$<str$> > >]
+// cdb-check:    [...] __0              : "Some error message" [Type: ref$<str$>]
 
 fn main() {
     let x: Result<i32, &str> = Ok(-3);
diff --git a/src/test/debuginfo/type-names.rs b/src/test/debuginfo/type-names.rs
index 9cc99d7767c..d7b79a845d2 100644
--- a/src/test/debuginfo/type-names.rs
+++ b/src/test/debuginfo/type-names.rs
@@ -95,7 +95,7 @@
 // gdb-check:type = &[usize]
 
 // gdb-command:whatis slice2
-// gdb-check:type = &[type_names::mod1::Enum2]
+// gdb-check:type = &mut [type_names::mod1::Enum2]
 
 // TRAITS
 // gdb-command:whatis box_trait
@@ -218,8 +218,8 @@
 // cdb-check:struct alloc::vec::Vec<usize,alloc::alloc::Global> vec1 = [...]
 // cdb-check:struct alloc::vec::Vec<enum2$<type_names::mod1::Enum2>,alloc::alloc::Global> vec2 = [...]
 // cdb-command:dv /t slice*
-// cdb-check:struct slice$<usize> slice1 = [...]
-// cdb-check:struct slice$<enum2$<type_names::mod1::Enum2> > slice2 = [...]
+// cdb-check:struct ref$<slice2$<usize> > slice1 = [...]
+// cdb-check:struct ref_mut$<slice2$<enum2$<type_names::mod1::Enum2> > > slice2 = [...]
 
 // TRAITS
 // cdb-command:dv /t *_trait
@@ -417,8 +417,8 @@ fn main() {
 
     let vec1 = vec![0_usize, 2, 3];
     let slice1 = &*vec1;
-    let vec2 = vec![mod1::Enum2::Variant2(Struct1)];
-    let slice2 = &*vec2;
+    let mut vec2 = vec![mod1::Enum2::Variant2(Struct1)];
+    let slice2 = &mut *vec2;
 
     // Trait Objects
     let box_trait = Box::new(0_isize) as Box<dyn Trait1>;
diff --git a/src/test/debuginfo/unsized.rs b/src/test/debuginfo/unsized.rs
index 7cb0002ca51..b1ec9b06830 100644
--- a/src/test/debuginfo/unsized.rs
+++ b/src/test/debuginfo/unsized.rs
@@ -32,13 +32,13 @@
 
 // cdb-command: g
 // cdb-command:dx a
-// cdb-check:a                [Type: ref$<unsized::Foo<slice$<u8> > >]
-// cdb-check:    [+0x000] data_ptr         : 0x[...] [Type: unsized::Foo<slice$<u8> > *]
+// cdb-check:a                [Type: ref$<unsized::Foo<slice2$<u8> > >]
+// cdb-check:    [+0x000] data_ptr         : 0x[...] [Type: unsized::Foo<slice2$<u8> > *]
 // cdb-check:    [...] length           : 0x4 [Type: unsigned [...]int[...]
 
 // cdb-command:dx b
-// cdb-check:b                [Type: ref$<unsized::Foo<unsized::Foo<slice$<u8> > > >]
-// cdb-check:    [+0x000] data_ptr         : 0x[...] [Type: unsized::Foo<unsized::Foo<slice$<u8> > > *]
+// cdb-check:b                [Type: ref$<unsized::Foo<unsized::Foo<slice2$<u8> > > >]
+// cdb-check:    [+0x000] data_ptr         : 0x[...] [Type: unsized::Foo<unsized::Foo<slice2$<u8> > > *]
 // cdb-check:    [...] length           : 0x4 [Type: unsigned [...]int[...]
 
 // cdb-command:dx c
@@ -53,8 +53,8 @@
 // cdb-check:[...] vtable           : 0x[...] [Type: unsigned [...]int[...] (*)[3]]
 
 // cdb-command:dx tuple_slice
-// cdb-check:tuple_slice      [Type: ref$<tuple$<i32,i32,slice$<i32> > >]
-// cdb-check:    [+0x000] data_ptr         : 0x[...] [Type: tuple$<i32,i32,slice$<i32> > *]
+// cdb-check:tuple_slice      [Type: ref$<tuple$<i32,i32,slice2$<i32> > >]
+// cdb-check:    [+0x000] data_ptr         : 0x[...] [Type: tuple$<i32,i32,slice2$<i32> > *]
 // cdb-check:    [...] length           : 0x2 [Type: unsigned [...]int[...]
 
 // cdb-command:dx tuple_dyn