diff --git a/crates/ide/src/syntax_highlighting/format.rs b/crates/ide/src/syntax_highlighting/format.rs
index b755a945cdb..6f6671f8ca7 100644
--- a/crates/ide/src/syntax_highlighting/format.rs
+++ b/crates/ide/src/syntax_highlighting/format.rs
@@ -28,9 +28,18 @@ pub(super) fn highlight_format_string(
}
fn is_format_string(string: &ast::String) -> Option<()> {
- let parent = string.syntax().parent()?;
+ // Check if `string` is a format string argument of a macro invocation.
+ // `string` is a string literal, mapped down into the innermost macro expansion.
+ // Since `format_args!` etc. remove the format string when expanding, but place all arguments
+ // in the expanded output, we know that the string token is (part of) the format string if it
+ // appears in `format_args!` (otherwise it would have been mapped down further).
+ //
+ // This setup lets us correctly highlight the components of `concat!("{}", "bla")` format
+ // strings. It still fails for `concat!("{", "}")`, but that is rare.
+
+ let macro_call = string.syntax().ancestors().find_map(ast::MacroCall::cast)?;
+ let name = macro_call.path()?.segment()?.name_ref()?;
- let name = parent.parent().and_then(ast::MacroCall::cast)?.path()?.segment()?.name_ref()?;
if !matches!(
name.text().as_str(),
"format_args" | "format_args_nl" | "const_format_args" | "panic_2015" | "panic_2021"
@@ -41,13 +50,6 @@ fn is_format_string(string: &ast::String) -> Option<()> {
// NB: we match against `panic_2015`/`panic_2021` here because they have a special-cased arm for
// `"{}"`, which otherwise wouldn't get highlighted.
- let first_literal = parent
- .children_with_tokens()
- .find_map(|it| it.as_token().cloned().and_then(ast::String::cast))?;
- if &first_literal != string {
- return None;
- }
-
Some(())
}
diff --git a/crates/ide/src/syntax_highlighting/test_data/highlight_strings.html b/crates/ide/src/syntax_highlighting/test_data/highlight_strings.html
index 4f67c4316a4..893094b24a4 100644
--- a/crates/ide/src/syntax_highlighting/test_data/highlight_strings.html
+++ b/crates/ide/src/syntax_highlighting/test_data/highlight_strings.html
@@ -145,4 +145,5 @@ pre { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
assert!(true, "{} asdasd", 1);
toho!("{}fmt", 0);
asm!("mov eax, {0}");
+ format_args!(concat!("{}"), "{}");
}
\ No newline at end of file
diff --git a/crates/ide/src/syntax_highlighting/tests.rs b/crates/ide/src/syntax_highlighting/tests.rs
index fd8e1a0e21d..18f562f0b1b 100644
--- a/crates/ide/src/syntax_highlighting/tests.rs
+++ b/crates/ide/src/syntax_highlighting/tests.rs
@@ -540,6 +540,7 @@ fn main() {
assert!(true, "{} asdasd", 1);
toho!("{}fmt", 0);
asm!("mov eax, {0}");
+ format_args!(concat!("{}"), "{}");
}"#
.trim(),
expect_file!["./test_data/highlight_strings.html"],