Less hacky assert! expansion

Author: jonas-schievink

crates/hir_expand/src/builtin_macro.rs

@@ -180,22 +180,28 @@ fn assert_expand(
     _id: MacroCallId,
     tt: &tt::Subtree,
 ) -> ExpandResult<tt::Subtree> {
-    // A hacky implementation for goto def and hover
-    // We expand `assert!(cond, arg1, arg2)` to
-    // ```
-    // {(cond, &(arg1), &(arg2));}
-    // ```,
-    // which is wrong but useful.
-
+    let krate = tt::Ident { text: "$crate".into(), id: tt::TokenId::unspecified() };
     let args = parse_exprs_with_sep(tt, ',');
-
-    let arg_tts = args.into_iter().flat_map(|arg| {
-        quote! { &(#arg), }
-    }.token_trees);
-
-    let expanded = quote! {
-        { { (##arg_tts); } }
+    let expanded = match &*args {
+        [cond, panic_args @ ..] => {
+            let cond = cond.clone();
+            let panic_args = panic_args.iter().cloned().intersperse(tt::Subtree {
+                delimiter: None,
+                token_trees: vec![tt::TokenTree::Leaf(tt::Leaf::Punct(tt::Punct {
+                    char: ',',
+                    spacing: tt::Spacing::Alone,
+                    id: tt::TokenId::unspecified(),
+                }))],
+            });
+            quote! {{
+                if !#cond {
+                    #krate::panic!(##panic_args);
+                }
+            }}
+        }
+        [] => quote! {{}},
     };
+
     ExpandResult::ok(expanded)
 }
 
@@ -731,7 +737,7 @@ mod tests {
             }
             assert!(true, "{} {:?}", arg1(a, b, c), arg2);
             "#,
-            expect![["{{(&(true), &(\"{} {:?}\"), &(arg1(a,b,c)), &(arg2),);}}"]],
+            expect![[r#"{if!true{$crate::panic!("{} {:?}",arg1(a,b,c),arg2);}}"#]],
         );
     }
 

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

@@ -74,7 +74,10 @@
 <span class="brace">}</span>
 
 <span class="attribute attribute">#</span><span class="attribute attribute">[</span><span class="builtin_attr attribute">rustc_builtin_macro</span><span class="parenthesis attribute">(</span><span class="none attribute">std_panic</span><span class="parenthesis attribute">)</span><span class="attribute attribute">]</span>
+<span class="attribute attribute">#</span><span class="attribute attribute">[</span><span class="builtin_attr attribute">macro_export</span><span class="attribute attribute">]</span>
 <span class="keyword">macro_rules</span><span class="punctuation">!</span> <span class="macro declaration">panic</span> <span class="brace">{</span><span class="brace">}</span>
+<span class="attribute attribute">#</span><span class="attribute attribute">[</span><span class="builtin_attr attribute">rustc_builtin_macro</span><span class="attribute attribute">]</span>
+<span class="keyword">macro_rules</span><span class="punctuation">!</span> <span class="macro declaration">assert</span> <span class="brace">{</span><span class="brace">}</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="comment">// from https://doc.rust-lang.org/std/fmt/index.html</span>
@@ -127,4 +130,6 @@
     <span class="macro">println!</span><span class="parenthesis">(</span><span class="string_literal">"</span><span class="format_specifier">{</span><span class="format_specifier">:</span><span class="variable">x</span><span class="format_specifier">?</span><span class="format_specifier">}</span><span class="string_literal"> </span><span class="format_specifier">{</span><span class="format_specifier">}</span><span class="string_literal"> "</span><span class="comma">,</span> thingy<span class="comma">,</span> n2<span class="parenthesis">)</span><span class="semicolon">;</span>
     <span class="macro">panic!</span><span class="parenthesis">(</span><span class="string_literal">"</span><span class="format_specifier">{</span><span class="format_specifier">}</span><span class="string_literal">"</span><span class="comma">,</span> <span class="numeric_literal">0</span><span class="parenthesis">)</span><span class="semicolon">;</span>
     <span class="macro">panic!</span><span class="parenthesis">(</span><span class="string_literal">"more </span><span class="format_specifier">{</span><span class="format_specifier">}</span><span class="string_literal">"</span><span class="comma">,</span> <span class="numeric_literal">1</span><span class="parenthesis">)</span><span class="semicolon">;</span>
+    <span class="macro">assert!</span><span class="parenthesis">(</span><span class="bool_literal">true</span><span class="comma">,</span> <span class="string_literal">"</span><span class="format_specifier">{</span><span class="format_specifier">}</span><span class="string_literal">"</span><span class="comma">,</span> <span class="numeric_literal">1</span><span class="parenthesis">)</span><span class="semicolon">;</span>
+    <span class="macro">assert!</span><span class="parenthesis">(</span><span class="bool_literal">true</span><span class="comma">,</span> <span class="string_literal">"</span><span class="format_specifier">{</span><span class="format_specifier">}</span><span class="string_literal"> asdasd"</span><span class="comma">,</span> <span class="numeric_literal">1</span><span class="parenthesis">)</span><span class="semicolon">;</span>
 <span class="brace">}</span></code></pre>

crates/ide/src/syntax_highlighting/tests.rs

@@ -469,7 +469,10 @@ mod panic {
 }
 
 #[rustc_builtin_macro(std_panic)]
+#[macro_export]
 macro_rules! panic {}
+#[rustc_builtin_macro]
+macro_rules! assert {}
 
 fn main() {
     // from https://doc.rust-lang.org/std/fmt/index.html
@@ -522,6 +525,8 @@ fn main() {
     println!("{:x?} {} ", thingy, n2);
     panic!("{}", 0);
     panic!("more {}", 1);
+    assert!(true, "{}", 1);
+    assert!(true, "{} asdasd", 1);
 }"#
         .trim(),
         expect_file!["./test_data/highlight_strings.html"],