Improve error message for rustdoc_json_types tidy check

Only emit git errors if we are in CI environment

Author: GuillaumeGomez

src/tools/tidy/src/rustdoc_json.rs

@@ -9,33 +9,41 @@ use build_helper::ci::CiEnv;
 use build_helper::git::{GitConfig, get_closest_upstream_commit};
 use build_helper::stage0_parser::parse_stage0_file;
 
+const RUSTDOC_JSON_TYPES: &str = "src/rustdoc-json-types";
+
 fn git_diff<S: AsRef<OsStr>>(base_commit: &str, extra_arg: S) -> Option<String> {
     let output = Command::new("git").arg("diff").arg(base_commit).arg(extra_arg).output().ok()?;
     Some(String::from_utf8_lossy(&output.stdout).into())
 }
 
+fn error_if_in_ci(ci_env: CiEnv, msg: &str, bad: &mut bool) {
+    if ci_env.is_ci() {
+        *bad = true;
+        eprintln!("error in `rustdoc_json` tidy check: {message}");
+    } else {
+        eprintln!("{message}. Skipping `rustdoc_json` tidy check");
+    }
+}
+
 pub fn check(src_path: &Path, bad: &mut bool) {
     println!("Checking tidy rustdoc_json...");
     let stage0 = parse_stage0_file();
+    let ci_env = CiEnv::current();
     let base_commit = match get_closest_upstream_commit(
         None,
         &GitConfig {
             nightly_branch: &stage0.config.nightly_branch,
             git_merge_commit_email: &stage0.config.git_merge_commit_email,
         },
-        CiEnv::current(),
+        ci_env,
     ) {
         Ok(Some(commit)) => commit,
         Ok(None) => {
-            *bad = true;
-            eprintln!("error: no base commit found for rustdoc_json check");
+            error_if_in_ci(ci_env, "no base commit found", bad);
             return;
         }
         Err(error) => {
-            *bad = true;
-            eprintln!(
-                "error: failed to retrieve base commit for rustdoc_json check because of `{error}`"
-            );
+            error_if_in_ci(ci_env, "failed to retrieve base commit", bad);
             return;
         }
     };
@@ -45,7 +53,7 @@ pub fn check(src_path: &Path, bad: &mut bool) {
         Some(output) => {
             if !output
                 .lines()
-                .any(|line| line.starts_with("M") && line.contains("src/rustdoc-json-types"))
+                .any(|line| line.starts_with("M") && line.contains(RUSTDOC_JSON_TYPES))
             {
                 // `rustdoc-json-types` was not modified so nothing more to check here.
                 println!("`rustdoc-json-types` was not modified.");
@@ -74,11 +82,13 @@ pub fn check(src_path: &Path, bad: &mut bool) {
                 *bad = true;
                 if latest_feature_comment_updated {
                     eprintln!(
-                        "error: `Latest feature` comment was updated whereas `FORMAT_VERSION` wasn't"
+                        "error in `rustdoc_json` tidy check: `Latest feature` comment was updated \
+                         whereas `FORMAT_VERSION` wasn't in `{RUSTDOC_JSON_TYPES}/lib.rs`"
                     );
                 } else {
                     eprintln!(
-                        "error: `Latest feature` comment was not updated whereas `FORMAT_VERSION` was"
+                        "error in `rustdoc_json` tidy check: `Latest feature` comment was not \
+                         updated whereas `FORMAT_VERSION` was in `{RUSTDOC_JSON_TYPES}/lib.rs`"
                     );
                 }
             }