Invalid XML file generated for Isabelle 2019 for a VC in micro-C
I have a micro-C file pgcd.c with two lemmas for provings the VCs. When trying to prove lemma gcd_ab in Isabelle 2019, I get errors in the .thy file pgcd_Pgcd_gcd_ab_2.thy that come from an issue in the generated .xml file pgcd_Pgcd_gcd_ab_2.xml.
The first error (in the .xml file) gives:
Malformed global fact "pgcd_Pgcd_gcd_ab_2.gcd_ab.facts.mixfix_lblsmnrbqtspec(1)" Illegal fixed variable: "'a"