Support the SMT-LIB Unicode string standard by default (#4378)

This PR merges --lang=smt2.6.1 and --lang=smt2.6 (default). It makes it so that 2.6 always expects the syntax of the string standard http://smtlib.cs.uiowa.edu/theories-UnicodeStrings.shtml.

I've updated the regressions so that the 2.6 benchmarks are now compliant with the standard. Some of the <=2.5 benchmarks I've updated to 2.6. Others I have left for now, in particular the ones that rely on special characters or ad-hoc escape sequences. The old formats will be supported in the release but removed shortly afterwards.

This PR is a prerequisite for the release, but not necessarily SMT-COMP (which will use --lang=smt2.6.1 if needed). Notice that we still do not have parsing support for str.replace_re or str.replace_re_all. This is required to be fully compliant.

1 files changed, 7 insertions, 16 deletions

diff --git a/src/printer/smt2/smt2_printer.cpp b/src/printer/smt2/smt2_printer.cpp
index 4013cbd08..fbccd26ed 100644
--- a/src/printer/smt2/smt2_printer.cpp
+++ b/src/printer/smt2/smt2_printer.cpp
@@ -48,10 +48,7 @@ static OutputLanguage variantToLanguage(Variant v);
 static string smtKindString(Kind k, Variant v);
 
 /** returns whether the variant is smt-lib 2.6 or greater */
-bool isVariant_2_6(Variant v)
-{
-  return v == smt2_6_variant || v == smt2_6_1_variant;
-}
+bool isVariant_2_6(Variant v) { return v == smt2_6_variant; }
 
 static void toStreamRational(std::ostream& out,
                              const Rational& r,
@@ -1203,8 +1200,7 @@ static string smtKindString(Kind k, Variant v)
   case kind::STRING_CHARAT: return "str.at" ;
   case kind::STRING_STRIDOF: return "str.indexof" ;
   case kind::STRING_STRREPL: return "str.replace" ;
-  case kind::STRING_STRREPLALL:
-    return v == smt2_6_1_variant ? "str.replace_all" : "str.replaceall";
+  case kind::STRING_STRREPLALL: return "str.replace_all";
   case kind::STRING_TOLOWER: return "str.tolower";
   case kind::STRING_TOUPPER: return "str.toupper";
   case kind::STRING_REV: return "str.rev";
@@ -1213,16 +1209,11 @@ static string smtKindString(Kind k, Variant v)
   case kind::STRING_LEQ: return "str.<=";
   case kind::STRING_LT: return "str.<";
   case kind::STRING_FROM_CODE: return "str.from_code";
-  case kind::STRING_TO_CODE:
-    return v == smt2_6_1_variant ? "str.to_code" : "str.code";
-  case kind::STRING_ITOS:
-    return v == smt2_6_1_variant ? "str.from_int" : "int.to.str";
-  case kind::STRING_STOI:
-    return v == smt2_6_1_variant ? "str.to_int" : "str.to.int";
-  case kind::STRING_IN_REGEXP:
-    return v == smt2_6_1_variant ? "str.in_re" : "str.in.re";
-  case kind::STRING_TO_REGEXP:
-    return v == smt2_6_1_variant ? "str.to_re" : "str.to.re";
+  case kind::STRING_TO_CODE: return "str.to_code";
+  case kind::STRING_ITOS: return "str.from_int";
+  case kind::STRING_STOI: return "str.to_int";
+  case kind::STRING_IN_REGEXP: return "str.in_re";
+  case kind::STRING_TO_REGEXP: return "str.to_re";
   case kind::REGEXP_EMPTY: return "re.nostr";
   case kind::REGEXP_SIGMA: return "re.allchar";
   case kind::REGEXP_CONCAT: return "re.++";