Fix build tests failing in CI.

--deny=warnings changes the error message for the tests too.

.github/workflows/ci.yml

@@ -8,7 +8,7 @@ on:
 env:
   CARGO_TERM_COLOR: always
   RUST_BACKTRACE: 1
-  RUSTFLAGS: '--codegen=debuginfo=0 --deny=warnings'
+  RUSTFLAGS: '--codegen=debuginfo=0'
 
 jobs:
   test:

tools/do-tasks/src/main.rs

@@ -277,18 +277,20 @@ fn test(mut args: Vec<&str>) {
                 )],
             );
 
-            let mut changes = 0;
+            let mut changes = vec![];
             for m in util::git_modified() {
                 if let Some(ext) = m.extension() {
                     if ext == "stderr" && m.starts_with("tests/build/cases") {
-                        changes += 1;
                         error(format!("build test `{}` modified", m.display()));
-                        util::print_git_diff(&m);
+                        changes.push(m);
                     }
                 }
             }
-            if changes > 0 {
-                fatal(format!("{changes} build tests modified, review and commit"));
+            if !changes.is_empty() {
+                for m in &changes {
+                    util::print_git_diff(&m);
+                }
+                fatal(format!("{} build tests modified, review and commit", changes.len()));
             }
         }
     } else if take_flag(&mut args, &["--examples"]) {

tools/do-tasks/src/util.rs

@@ -444,4 +444,4 @@ pub fn git_modified() -> Vec<PathBuf> {
 
 pub fn print_git_diff(file: &std::path::Path) {
     Command::new("git").arg("diff").arg(file).status().unwrap();
-}
+}