Match a bug entry with its WARN condition to the rule for the site without it

crates/rk/src/sections.rs

@@ -643,6 +643,17 @@ fn matches(pattern: &str, s: &str) -> bool {
     }
 }
 
+/// A bug entry's site without the condition text of its WARN.
+///
+/// With `DEBUG_BUGVERBOSE_DETAILED` a `WARN_ON(cond)` puts `#cond` where the format of a `WARN`
+/// goes, so allmodconfig prints `4="!p" 8="mm/x.c" 1c000309` for the site defconfig prints as
+/// `4="" 8="mm/x.c" 1c000309`. The file, line and flags still name it.
+fn uncondition(item: &str) -> Option<String> {
+    let rest = item.strip_prefix("4=\"")?;
+    let at = rest.find("\" 8=\"")?;
+    (at > 0).then(|| format!("4=\"\"{}", &rest[at + 1..]))
+}
+
 /// Whether a rule for `object` follows `item` into the module `object` is linked into.
 ///
 /// A bug entry names the file of its WARN or BUG. One that names `fs/btrfs/volumes.c` was compiled
@@ -689,14 +700,17 @@ impl Divergences {
     }
 
     /// The rule that explains one item of a difference, if there is one.
+    ///
+    /// A bug entry with the condition text of its WARN is the site a rule names without it.
     fn rule(&self, d: &Difference, only: Only, item: &str) -> Option<&Divergence> {
+        let bare = uncondition(item);
         self.divergences.iter().find(|r| {
             r.what == d.what
                 && (r.only == only || r.only == Only::Either)
                 && r.object
                     .as_deref()
                     .is_none_or(|o| matches(o, &d.object) || linked(o, item))
-                && matches(&r.item, item)
+                && (matches(&r.item, item) || bare.as_deref().is_some_and(|b| matches(&r.item, b)))
         })
     }
 
@@ -1591,6 +1605,21 @@ reason = "checked in a.c"
         std::fs::remove_dir_all(&dir).unwrap();
     }
 
+    #[test]
+    fn a_site_with_its_condition_is_the_site_without_it() {
+        let rules = Divergences::parse(
+            "[[divergence]]\nwhat = \"__bug_table\"\nonly = \"reference\"\n\
+             item = '4=\"\" 8=\"mm/x.c\" 1c000309'\nreason = \"r\"\n",
+        )
+        .unwrap();
+        let d = plain("mm/x.o", "__bug_table", String::new(), String::new());
+        let at = |item: &str| rules.rule(&d, Only::Reference, item).is_some();
+        assert!(at("4=\"\" 8=\"mm/x.c\" 1c000309"));
+        assert!(at("4=\"!p\" 8=\"mm/x.c\" 1c000309"));
+        assert!(!at("4=\"!p\" 8=\"mm/x.c\" 1d000309"));
+        assert_eq!(uncondition("4=\"\" 8=\"mm/x.c\" 1c000309"), None);
+    }
+
     #[test]
     fn the_divergences_file_parses_and_every_rule_has_a_reason() {
         let rules = Divergences::parse(include_str!("../../../sections-divergences.toml")).unwrap();

sections-divergences.toml

@@ -2315,6 +2315,19 @@ only = "reference"
 item = '4="net/bluetooth/hci_event.c" f5170909'
 reason = "the field spanning WARN of memcpy(conn->le_adv_data, data, len) in process_adv_report, which runs under len <= max_adv_len(hdev), 31 or 251, the size of le_adv_data. rucc carries the bound"
 
+[[divergence]]
+what = "__bug_table"
+only = "reference"
+item = '4="" 8="include/linux/netfilter.h" *'
+reason = "the two WARN_ON_ONCEs in nf_hook, the hook >= ARRAY_SIZE(hooks_arp) for NFPROTO_ARP and the one in the default case. Every NF_HOOK and nf_hook call passes pf and hook as constants, so rucc inlines nf_hook into each caller and folds the switch, where gcc keeps one copy with both checks"
+
+[[divergence]]
+what = "__bug_table"
+object = "drivers/net/ethernet/mellanox/mlxsw/*"
+only = "reference"
+item = '4="" 8="drivers/net/ethernet/mellanox/mlxsw/item.h" *'
+reason = "the BUG_ON(index && !item->step) and the alignment BUG() in __mlxsw_item_offset on 7.2. The items are const file scope MLXSW_ITEMs, so once rucc folds them each check is false, and gcc keeps the checks in its out of line copies such as __mlxsw_item_get32.constprop.0"
+
 [[divergence]]
 what = "__bug_table"
 object = "net/bridge/br_netfilter.o"