Rollup merge of #146171 - scrabsha:push-wovnxxwltsun, r=WaffleLapkin

tidy: check that error messages don't start with a capitalized letter

3 files changed, 66 insertions, 0 deletions

diff --git a/src/tools/tidy/src/fluent_lowercase.rs b/src/tools/tidy/src/fluent_lowercase.rs
new file mode 100644
index 00000000000..13f0319909e
--- /dev/null
+++ b/src/tools/tidy/src/fluent_lowercase.rs
@@ -0,0 +1,64 @@
+//! Checks that the error messages start with a lowercased letter (except when allowed to).
+
+use std::path::Path;
+
+use fluent_syntax::ast::{Entry, Message, PatternElement};
+
+use crate::walk::{filter_dirs, walk};
+
+#[rustfmt::skip]
+const ALLOWED_CAPITALIZED_WORDS: &[&str] = &[
+    // tidy-alphabetical-start
+    "ABI",
+    "ABIs",
+    "ADT",
+    "C",
+    "CGU",
+    "Ferris",
+    "MIR",
+    "OK",
+    "Rust",
+    "VS", // VS Code
+    // tidy-alphabetical-end
+];
+
+fn filter_fluent(path: &Path) -> bool {
+    if let Some(ext) = path.extension() { ext.to_str() != Some("ftl") } else { true }
+}
+
+fn is_allowed_capitalized_word(msg: &str) -> bool {
+    ALLOWED_CAPITALIZED_WORDS.iter().any(|word| {
+        msg.strip_prefix(word)
+            .map(|tail| tail.chars().next().map(|c| c == '-' || c.is_whitespace()).unwrap_or(true))
+            .unwrap_or_default()
+    })
+}
+
+fn check_lowercase(filename: &str, contents: &str, bad: &mut bool) {
+    let (Ok(parse) | Err((parse, _))) = fluent_syntax::parser::parse(contents);
+
+    for entry in &parse.body {
+        if let Entry::Message(msg) = entry
+            && let Message { value: Some(pattern), .. } = msg
+            && let [first_pattern, ..] = &pattern.elements[..]
+            && let PatternElement::TextElement { value } = first_pattern
+            && value.chars().next().is_some_and(char::is_uppercase)
+            && !is_allowed_capitalized_word(value)
+        {
+            tidy_error!(
+                bad,
+                "{filename}: message `{value}` starts with an uppercase letter. Fix it or add it to `ALLOWED_CAPITALIZED_WORDS`"
+            );
+        }
+    }
+}
+
+pub fn check(path: &Path, bad: &mut bool) {
+    walk(
+        path,
+        |path, is_dir| filter_dirs(path) || (!is_dir && filter_fluent(path)),
+        &mut |ent, contents| {
+            check_lowercase(ent.path().to_str().unwrap(), contents, bad);
+        },
+    );
+}
diff --git a/src/tools/tidy/src/lib.rs b/src/tools/tidy/src/lib.rs
index 37713cbf75e..2a9c3963d2d 100644
--- a/src/tools/tidy/src/lib.rs
+++ b/src/tools/tidy/src/lib.rs
@@ -257,6 +257,7 @@ pub mod extra_checks;
 pub mod features;
 pub mod filenames;
 pub mod fluent_alphabetical;
+pub mod fluent_lowercase;
 pub mod fluent_period;
 mod fluent_used;
 pub mod gcc_submodule;
diff --git a/src/tools/tidy/src/main.rs b/src/tools/tidy/src/main.rs
index bfe30258915..f9e82341b7a 100644
--- a/src/tools/tidy/src/main.rs
+++ b/src/tools/tidy/src/main.rs
@@ -121,6 +121,7 @@ fn main() {
         check!(error_codes, &root_path, &[&compiler_path, &librustdoc_path], verbose, &ci_info);
         check!(fluent_alphabetical, &compiler_path, bless);
         check!(fluent_period, &compiler_path);
+        check!(fluent_lowercase, &compiler_path);
         check!(target_policy, &root_path);
         check!(gcc_submodule, &root_path, &compiler_path);