Merge pull request github#17746 from github/aibaars/macro-pat-irrefutable

Rust: add MacroPat to isExhaustiveMatch

Author: aibaars

rust/ql/lib/codeql/rust/controlflow/internal/Completion.qll

@@ -139,6 +139,9 @@ private predicate isExhaustiveMatch(Pat pat) {
     // `match` expressions must be exhaustive, so last arm cannot fail
     pat = any(MatchExpr me).getLastArm().getPat()
     or
+    // macro invocations are exhaustive if their expansion is
+    pat = any(MacroPat mp | isExhaustiveMatch(mp.getMacroCall().getExpanded()))
+    or
     // parameter patterns must be exhaustive
     pat = any(Param p).getPat()
   ) and
@@ -149,6 +152,8 @@ private predicate isExhaustiveMatch(Pat pat) {
     or
     pat = parent.(IdentPat).getPat()
     or
+    pat = parent.(MacroPat).getMacroCall().getExpanded()
+    or
     pat = parent.(ParenPat).getPat()
     or
     pat = parent.(RecordPat).getRecordPatFieldList().getField(_).getPat()