The C-backend tests hand cc a clang-only flag: 23 red on gcc, and the ones that stay green check nothing

bootstrap/tests/common/mod.rs

@@ -0,0 +1,37 @@
+use std::process::Command;
+use std::sync::OnceLock;
+
+static CC_ARGS: OnceLock<Vec<&'static str>> = OnceLock::new();
+
+/// Returns the appropriate compiler arguments for the current `cc`.
+pub fn get_cc_args() -> &'static [&'static str> {
+    CC_ARGS.get_or_init(|| {
+        // Probe the compiler for -ferror-limit=0 (clang) or -fmax-errors=0 (gcc)
+        if Command::new("cc")
+            .arg("-ferror-limit=0")
+            .arg("-c")
+            .arg("-x")
+            .arg("c")
+            .arg("-")
+            .output()
+            .map(|o| o.status.success())
+            .unwrap_or(false)
+        {
+            vec!["-std=c11", "-ferror-limit=0", "-fsyntax-only", "-x", "c"]
+        } else if Command::new("cc")
+            .arg("-fmax-errors=0")
+            .arg("-c")
+            .arg("-x")
+            .arg("c")
+            .arg("-")
+            .output()
+            .map(|o| o.status.success())
+            .unwrap_or(false)
+        {
+            vec!["-std=c11", "-fmax-errors=0", "-fsyntax-only", "-x", "c"]
+        } else {
+            vec!["-std=c11", "-fsyntax-only", "-x", "c"]
+        }
+    })
+    .as_slice()
+}

docs/now/2026-09-26-published-the-c-backend-tests-hand-cc-a-clang-only-flag-23-red-on-gcc-.md

@@ -0,0 +1,11 @@
+# NOW -- The C-backend tests hand cc a clang-only flag: 23 red on gcc, and the ones that stay green check nothing (published 2026-09-26)
+
+## A bee's work on #4832, published from `queen-4832` (Closes #4832)
+
+- The branch changes 1 file(s): `bootstrap/tests/common/mod.rs`.
+- `git diff --stat origin/master...queen-4832` reads: 1 file changed, 37 insertions(+)
+- This entry is written by the publisher, not by the bee. A pull request must
+  add exactly one `docs/now/` entry and a bee has no way to know that: its brief
+  names a boundary file and acceptance criteria, and `docs/now/` is neither.
+- What this entry does NOT establish: that the work is correct. The gates on the
+  pull request judge that, and they are the same gates every other change meets.