Rollup merge of #138063 - compiler-errors:improve-attr-unpretty, r=jdonszelmann

Improve `-Zunpretty=hir` for parsed attrs

0. Rename `print_something` to `should_render` to make it distinct from `print_attribute` in that it doesn't print anything, it's just a way to probe if a type renders anything.
1. Fixes a few bugs in the `PrintAttribute` derive. Namely, the `__printed_anything` variable was entangled with the `should_render` call, leading us to always render field names but never render commas.
2. Remove the outermost `""` from the attr.
3. Debug print `Symbol`s. I know that this is redundant for some parsed attributes, but there's no good way to distinguish symbols that are ident-like and symbols which are cooked string literals. We could perhaps *conditionally* to fall back to a debug printing if the symbol doesn't match an ident? But seems like overkill.

Based on #138060, only review the commits not in that one.

1 files changed, 16 insertions, 11 deletions

diff --git a/compiler/rustc_macros/src/print_attribute.rs b/compiler/rustc_macros/src/print_attribute.rs
index 3c6e30b851b..42d94e72ee9 100644
--- a/compiler/rustc_macros/src/print_attribute.rs
+++ b/compiler/rustc_macros/src/print_attribute.rs
@@ -16,12 +16,14 @@ fn print_fields(name: &Ident, fields: &Fields) -> (TokenStream, TokenStream, Tok
                 let name = field.ident.as_ref().unwrap();
                 let string_name = name.to_string();
                 disps.push(quote! {
-                    if __printed_anything && #name.print_something() {
-                        __p.word_space(",");
+                    if #name.should_render() {
+                        if __printed_anything {
+                            __p.word_space(",");
+                        }
+                        __p.word(#string_name);
+                        __p.word_space(":");
                         __printed_anything = true;
                     }
-                    __p.word(#string_name);
-                    __p.word_space(":");
                     #name.print_attribute(__p);
                 });
                 field_names.push(name);
@@ -31,10 +33,11 @@ fn print_fields(name: &Ident, fields: &Fields) -> (TokenStream, TokenStream, Tok
                 quote! { {#(#field_names),*} },
                 quote! {
                     __p.word(#string_name);
-                    if true #(&& !#field_names.print_something())* {
+                    if true #(&& !#field_names.should_render())* {
                         return;
                     }
 
+                    __p.nbsp();
                     __p.word("{");
                     #(#disps)*
                     __p.word("}");
@@ -48,8 +51,10 @@ fn print_fields(name: &Ident, fields: &Fields) -> (TokenStream, TokenStream, Tok
             for idx in 0..fields_unnamed.unnamed.len() {
                 let name = format_ident!("f{idx}");
                 disps.push(quote! {
-                    if __printed_anything && #name.print_something() {
-                        __p.word_space(",");
+                    if #name.should_render() {
+                        if __printed_anything {
+                            __p.word_space(",");
+                        }
                         __printed_anything = true;
                     }
                     #name.print_attribute(__p);
@@ -62,13 +67,13 @@ fn print_fields(name: &Ident, fields: &Fields) -> (TokenStream, TokenStream, Tok
                 quote! {
                     __p.word(#string_name);
 
-                    if true #(&& !#field_names.print_something())* {
+                    if true #(&& !#field_names.should_render())* {
                         return;
                     }
 
-                    __p.word("(");
+                    __p.popen();
                     #(#disps)*
-                    __p.word(")");
+                    __p.pclose();
                 },
                 quote! { true },
             )
@@ -138,7 +143,7 @@ pub(crate) fn print_attribute(input: Structure<'_>) -> TokenStream {
     input.gen_impl(quote! {
         #[allow(unused)]
         gen impl PrintAttribute for @Self {
-            fn print_something(&self) -> bool { #printed }
+            fn should_render(&self) -> bool { #printed }
             fn print_attribute(&self, __p: &mut rustc_ast_pretty::pp::Printer) { #code }
         }
     })