fix: Strip unused token ids from eager macro input token maps

Author: Veykril

crates/hir-expand/src/eager.rs

@@ -19,7 +19,7 @@
 //!
 //! See the full discussion : <https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/Eager.20expansion.20of.20built-in.20macros>
 use base_db::CrateId;
-use rustc_hash::FxHashMap;
+use rustc_hash::{FxHashMap, FxHashSet};
 use syntax::{ted, Parse, SyntaxNode, TextRange, TextSize, WalkEvent};
 use triomphe::Arc;
 
@@ -83,10 +83,11 @@ pub fn expand_eager_macro_input(
         mbe::syntax_node_to_token_tree(&expanded_eager_input);
 
     let og_tmap = if let Some(tt) = macro_call.value.token_tree() {
-        let og_tmap = mbe::syntax_node_to_token_map(tt.syntax());
+        let mut ids_used = FxHashSet::default();
+        let mut og_tmap = mbe::syntax_node_to_token_map(tt.syntax());
         // The tokenmap and ids of subtree point into the expanded syntax node, but that is inaccessible from the outside
         // so we need to remap them to the original input of the eager macro.
-        subtree.visit_ids(&|id| {
+        subtree.visit_ids(&mut |id| {
             // Note: we discard all token ids of braces and the like here, but that's not too bad and only a temporary fix
 
             if let Some(range) = expanded_eager_input_token_map
@@ -97,13 +98,15 @@ pub fn expand_eager_macro_input(
                     // remap from eager input expansion to original eager input
                     if let Some(&og_range) = ws_mapping.get(og_range) {
                         if let Some(og_token) = og_tmap.token_by_range(og_range) {
+                            ids_used.insert(id);
                             return og_token;
                         }
                     }
                 }
             }
             tt::TokenId::UNSPECIFIED
         });
+        og_tmap.filter(|id| ids_used.contains(&id));
         og_tmap
     } else {
         Default::default()

crates/ide/src/syntax_highlighting/test_data/highlight_macros.html

@@ -90,8 +90,18 @@
     <span class="brace">}</span>
 <span class="brace">}</span>
 
+<span class="attribute_bracket attribute">#</span><span class="attribute_bracket attribute">[</span><span class="builtin_attr attribute library">rustc_builtin_macro</span><span class="attribute_bracket attribute">]</span>
+<span class="keyword">macro_rules</span><span class="macro_bang">!</span> <span class="macro declaration">concat</span> <span class="brace">{</span><span class="brace">}</span>
+<span class="attribute_bracket attribute">#</span><span class="attribute_bracket attribute">[</span><span class="builtin_attr attribute library">rustc_builtin_macro</span><span class="attribute_bracket attribute">]</span>
+<span class="keyword">macro_rules</span><span class="macro_bang">!</span> <span class="macro declaration">include</span> <span class="brace">{</span><span class="brace">}</span>
+<span class="attribute_bracket attribute">#</span><span class="attribute_bracket attribute">[</span><span class="builtin_attr attribute library">rustc_builtin_macro</span><span class="attribute_bracket attribute">]</span>
+<span class="keyword">macro_rules</span><span class="macro_bang">!</span> <span class="macro declaration">format_args</span> <span class="brace">{</span><span class="brace">}</span>
+
+<span class="macro">include</span><span class="macro_bang">!</span><span class="parenthesis macro">(</span><span class="none macro">concat</span><span class="punctuation macro">!</span><span class="parenthesis macro">(</span><span class="string_literal macro">"foo/"</span><span class="comma macro">,</span> <span class="string_literal macro">"foo.rs"</span><span class="parenthesis macro">)</span><span class="parenthesis macro">)</span><span class="semicolon">;</span>
+
 <span class="keyword">fn</span> <span class="function declaration">main</span><span class="parenthesis">(</span><span class="parenthesis">)</span> <span class="brace">{</span>
-    <span class="unresolved_reference">println</span><span class="macro_bang">!</span><span class="parenthesis macro">(</span><span class="string_literal macro">"Hello, {}!"</span><span class="comma macro">,</span> <span class="numeric_literal macro">92</span><span class="parenthesis macro">)</span><span class="semicolon">;</span>
+    <span class="macro">format_args</span><span class="macro_bang">!</span><span class="parenthesis macro">(</span><span class="string_literal macro">"Hello, </span><span class="format_specifier">{</span><span class="format_specifier">}</span><span class="string_literal macro">!"</span><span class="comma macro">,</span> <span class="numeric_literal macro">92</span><span class="parenthesis macro">)</span><span class="semicolon">;</span>
     <span class="macro">dont_color_me_braces</span><span class="macro_bang">!</span><span class="parenthesis macro">(</span><span class="parenthesis macro">)</span><span class="semicolon">;</span>
     <span class="macro">noop</span><span class="macro_bang">!</span><span class="parenthesis macro">(</span><span class="macro macro">noop</span><span class="macro_bang macro">!</span><span class="parenthesis macro">(</span><span class="numeric_literal macro">1</span><span class="parenthesis macro">)</span><span class="parenthesis macro">)</span><span class="semicolon">;</span>
-<span class="brace">}</span></code></pre>
+<span class="brace">}</span>
+</code></pre>

crates/ide/src/syntax_highlighting/tests.rs

@@ -48,6 +48,7 @@ fn macros() {
     check_highlighting(
         r#"
 //- proc_macros: mirror
+//- /lib.rs crate:lib
 proc_macros::mirror! {
     {
         ,i32 :x pub
@@ -95,11 +96,23 @@ macro without_args {
     }
 }
 
+#[rustc_builtin_macro]
+macro_rules! concat {}
+#[rustc_builtin_macro]
+macro_rules! include {}
+#[rustc_builtin_macro]
+macro_rules! format_args {}
+
+include!(concat!("foo/", "foo.rs"));
+
 fn main() {
-    println!("Hello, {}!", 92);
+    format_args!("Hello, {}!", 92);
     dont_color_me_braces!();
     noop!(noop!(1));
 }
+//- /foo/foo.rs crate:foo
+mod foo {}
+use self::foo as bar;
 "#,
         expect_file!["./test_data/highlight_macros.html"],
         false,

crates/mbe/src/token_map.rs

@@ -117,4 +117,8 @@ impl TokenMap {
             TokenTextRange::Delimiter(_) => None,
         })
     }
+
+    pub fn filter(&mut self, id: impl Fn(tt::TokenId) -> bool) {
+        self.entries.retain(|&(tid, _)| id(tid));
+    }
 }

crates/tt/src/lib.rs

@@ -70,7 +70,7 @@ pub mod token_id {
     }
 
     impl Subtree {
-        pub fn visit_ids(&mut self, f: &impl Fn(TokenId) -> TokenId) {
+        pub fn visit_ids(&mut self, f: &mut impl FnMut(TokenId) -> TokenId) {
             self.delimiter.open = f(self.delimiter.open);
             self.delimiter.close = f(self.delimiter.close);
             self.token_trees.iter_mut().for_each(|tt| match tt {