From 1b587a6e76200fdd8364ef910246efa11c973e7b Mon Sep 17 00:00:00 2001
From: Michael Howell <michael@notriddle.com>
Date: Tue, 6 Aug 2024 14:33:14 -0700
Subject: alloc: add ToString specialization for `&&str`

Fixes #128690
---
 library/alloc/src/string.rs | 43 +++++++++++++++++++++++++++++++++++--------
 1 file changed, 35 insertions(+), 8 deletions(-)

(limited to 'library/alloc/src/string.rs')

diff --git a/library/alloc/src/string.rs b/library/alloc/src/string.rs
index 124230812df..d943901e9ec 100644
--- a/library/alloc/src/string.rs
+++ b/library/alloc/src/string.rs
@@ -2643,14 +2643,41 @@ impl ToString for i8 {
     }
 }
 
-#[doc(hidden)]
-#[cfg(not(no_global_oom_handling))]
-#[stable(feature = "str_to_string_specialization", since = "1.9.0")]
-impl ToString for str {
-    #[inline]
-    fn to_string(&self) -> String {
-        String::from(self)
-    }
+// Generic/generated code can sometimes have multiple, nested references
+// for strings, including `&&&str`s that would never be written
+// by hand. This macro generates twelve layers of nested `&`-impl
+// for primitive strings.
+macro_rules! to_string_str {
+    {type ; x $($x:ident)*} => {
+        &to_string_str! { type ; $($x)* }
+    };
+    {type ;} => { str };
+    {impl ; x $($x:ident)*} => {
+        to_string_str! { $($x)* }
+    };
+    {impl ;} => { };
+    {$self:expr ; x $($x:ident)*} => {
+        *(to_string_str! { $self ; $($x)* })
+    };
+    {$self:expr ;} => { $self };
+    {$($x:ident)*} => {
+        #[doc(hidden)]
+        #[cfg(not(no_global_oom_handling))]
+        #[stable(feature = "str_to_string_specialization", since = "1.9.0")]
+        impl ToString for to_string_str!(type ; $($x)*) {
+            #[inline]
+            fn to_string(&self) -> String {
+                String::from(to_string_str!(self ; $($x)*))
+            }
+        }
+        to_string_str! { impl ; $($x)* }
+    };
+}
+
+to_string_str! {
+    x x x x
+    x x x x
+    x x x x
 }
 
 #[doc(hidden)]
-- 
cgit 1.4.1-3-g733a5


From 3312f5d65244b4ccb035be7b4c61541afc211914 Mon Sep 17 00:00:00 2001
From: Michael Howell <michael@notriddle.com>
Date: Wed, 7 Aug 2024 09:06:49 -0700
Subject: alloc: make `to_string_str!` a bit less complex

---
 library/alloc/src/string.rs | 57 ++++++++++++++++++++++++++++-----------------
 1 file changed, 35 insertions(+), 22 deletions(-)

(limited to 'library/alloc/src/string.rs')

diff --git a/library/alloc/src/string.rs b/library/alloc/src/string.rs
index d943901e9ec..e628be1546f 100644
--- a/library/alloc/src/string.rs
+++ b/library/alloc/src/string.rs
@@ -2647,37 +2647,50 @@ impl ToString for i8 {
 // for strings, including `&&&str`s that would never be written
 // by hand. This macro generates twelve layers of nested `&`-impl
 // for primitive strings.
-macro_rules! to_string_str {
-    {type ; x $($x:ident)*} => {
-        &to_string_str! { type ; $($x)* }
-    };
-    {type ;} => { str };
-    {impl ; x $($x:ident)*} => {
-        to_string_str! { $($x)* }
+#[cfg(not(no_global_oom_handling))]
+macro_rules! to_string_str_wrap_in_ref {
+    {x $($x:ident)*} => {
+        &to_string_str_wrap_in_ref! { $($x)* }
     };
-    {impl ;} => { };
+    {} => { str };
+}
+#[cfg(not(no_global_oom_handling))]
+macro_rules! to_string_expr_wrap_in_deref {
     {$self:expr ; x $($x:ident)*} => {
-        *(to_string_str! { $self ; $($x)* })
+        *(to_string_expr_wrap_in_deref! { $self ; $($x)* })
     };
     {$self:expr ;} => { $self };
-    {$($x:ident)*} => {
-        #[doc(hidden)]
-        #[cfg(not(no_global_oom_handling))]
-        #[stable(feature = "str_to_string_specialization", since = "1.9.0")]
-        impl ToString for to_string_str!(type ; $($x)*) {
-            #[inline]
-            fn to_string(&self) -> String {
-                String::from(to_string_str!(self ; $($x)*))
+}
+#[cfg(not(no_global_oom_handling))]
+macro_rules! to_string_str {
+    {$($($x:ident)*),+} => {
+        $(
+            #[doc(hidden)]
+            #[stable(feature = "str_to_string_specialization", since = "1.9.0")]
+            impl ToString for to_string_str_wrap_in_ref!($($x)*) {
+                #[inline]
+                fn to_string(&self) -> String {
+                    String::from(to_string_expr_wrap_in_deref!(self ; $($x)*))
+                }
             }
-        }
-        to_string_str! { impl ; $($x)* }
+        )+
     };
 }
 
+#[cfg(not(no_global_oom_handling))]
 to_string_str! {
-    x x x x
-    x x x x
-    x x x x
+    x x x x x x x x x x x x,
+    x x x x x x x x x x x,
+    x x x x x x x x x x,
+    x x x x x x x x x,
+    x x x x x x x x,
+    x x x x x x x,
+    x x x x x x,
+    x x x x x,
+    x x x x,
+    x x x,
+    x x,
+    x,
 }
 
 #[doc(hidden)]
-- 
cgit 1.4.1-3-g733a5