feat(cpp-matrix): warn-no-matches options

Author: alandefreitas

b2-workflow/package-lock.json

@@ -698,6 +698,15 @@ inputs:
     required: false
     default: 'false'
 
+  warn-no-matches:
+    description: |
+      Emit a GitHub warning whenever a compiler configuration results in zero matrix entries because
+      no known versions can satisfy the requested version range and C++ standard requirements simultaneously.
+      Leave this enabled to catch unintended gaps; set it to `false` if you deliberately provide
+      unsatisfiable requirements and do not want the additional annotation.
+    required: false
+    default: 'true'
+
 
 outputs:
   matrix: