From eea6f23a0ed67fd8c6b8e1b02cda3628fee56b2f Mon Sep 17 00:00:00 2001 From: Nicholas Nethercote Date: Thu, 24 Oct 2019 06:33:12 +1100 Subject: Make doc comments cheaper with `AttrKind`. `AttrKind` is a new type with two variants, `Normal` and `DocComment`. It's a big performance win (over 10% in some cases) because `DocComment` lets doc comments (which are common) be represented very cheaply. `Attribute` gets some new helper methods to ease the transition: - `has_name()`: check if the attribute name matches a single `Symbol`; for `DocComment` variants it succeeds if the symbol is `sym::doc`. - `is_doc_comment()`: check if it has a `DocComment` kind. - `{get,unwrap}_normal_item()`: extract the item from a `Normal` variant; panic otherwise. Fixes #60935. --- src/libsyntax_ext/proc_macro_harness.rs | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) (limited to 'src/libsyntax_ext') diff --git a/src/libsyntax_ext/proc_macro_harness.rs b/src/libsyntax_ext/proc_macro_harness.rs index bef91399927..792c97d8508 100644 --- a/src/libsyntax_ext/proc_macro_harness.rs +++ b/src/libsyntax_ext/proc_macro_harness.rs @@ -249,9 +249,11 @@ impl<'a> Visitor<'a> for CollectProcMacros<'a> { for attr in &item.attrs { if is_proc_macro_attr(&attr) { if let Some(prev_attr) = found_attr { - let path_str = pprust::path_to_string(&attr.item.path); - let msg = if attr.item.path.segments[0].ident.name == - prev_attr.item.path.segments[0].ident.name { + let prev_item = prev_attr.get_normal_item(); + let item = attr.get_normal_item(); + let path_str = pprust::path_to_string(&item.path); + let msg = if item.path.segments[0].ident.name == + prev_item.path.segments[0].ident.name { format!( "only one `#[{}]` attribute is allowed on any given function", path_str, @@ -261,7 +263,7 @@ impl<'a> Visitor<'a> for CollectProcMacros<'a> { "`#[{}]` and `#[{}]` attributes cannot both be applied to the same function", path_str, - pprust::path_to_string(&prev_attr.item.path), + pprust::path_to_string(&prev_item.path), ) }; @@ -290,7 +292,7 @@ impl<'a> Visitor<'a> for CollectProcMacros<'a> { if !is_fn { let msg = format!( "the `#[{}]` attribute may only be used on bare functions", - pprust::path_to_string(&attr.item.path), + pprust::path_to_string(&attr.get_normal_item().path), ); self.handler.span_err(attr.span, &msg); @@ -304,7 +306,7 @@ impl<'a> Visitor<'a> for CollectProcMacros<'a> { if !self.is_proc_macro_crate { let msg = format!( "the `#[{}]` attribute is only usable with crates of the `proc-macro` crate type", - pprust::path_to_string(&attr.item.path), + pprust::path_to_string(&attr.get_normal_item().path), ); self.handler.span_err(attr.span, &msg); -- cgit 1.4.1-3-g733a5