Unusual compiler error: 'unable to obtain the MIN value for type the ZType'

[Alice Osako]

    In pursuance of my previously
      mentioned UNICODE project, I have been trying to debug Chris
      Lilley's code such that it will hopefully compile. Aside from a
      problem with some non-POINTER opaque types which needed to be
      moved from the implementation file to the definition file, and
      fixing all of the hexadecimal numbers, the main issue I am having
      is in the function 'ASCIIToUNICHAR()' ('ASCIIToUChar()'  in
      Lilley's original). 
      
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      
      PROCEDURE ASCIIToUNICHAR (a: CHAR): UNICHAR;
      (*
         ASCIIToUNICHAR -  converts a single ASCII printable char, a,
      into
                         a Unicode character in the Basic Latin block.
                         For GM2, a Modula-2 char is a gcc char which is
      8 bits;
                         printable ASCII values take up the lower half
      of the
                         codespace in GM2.
                         If the ordinal value of a is outside the
      printable
                         ASCII range, the Unicode character
                         'REPLACEMENT CHARACTER' is returned.
                         The size and encoding of a Modula-2 char is
      undefined
                         in both PIM and ISO Modula-2.
      *)
      VAR
         ASCIIRange : [32..127];
         cp: CARDINAL;  (* Unicode codepoint of the passed ASCII
      character *)
      
      BEGIN
         cp := ORD(a);
         (* if the locale is ASCII, or an ASCII superset like Latin-1,
            cp will be the code point of the expected character.
            if the locale is a code-switching set, or EBCIDIC or
      something,
            then you get what you get, and should not be claiming it
      covers ASCII.
         *)
         IF (cp IN ASCIIRange) THEN
            RETURN cp;
         ELSE
            RETURN Replacement;
         END;
      END ASCIIToUNICHAR;
      
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      
      When compiled with no language version specifier, I get the
      following compiler error:
      
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    <library
      path>/gcc/x86_64-pc-linux-gnu/13.2.1/m2/m2pim/COROUTINES.def:37:1:
      error: In procedure ‘ASCIIToUNICHAR’: unable to obtain the MIN
      value for type the ZType
    <library path>/gcc/x86_64-pc-linux-gnu/13.2.1/m2/m2pim/COROUTINES.def:37:1:
      error: unable to obtain the MAX value for type the ZType
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      
    Curiously, when I
      specify '-fiso', the error comes out as:
      
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Unicode.mod: In function
      ‘Unicode_ASCIIToUNICHAR’:
      Unicode.mod:178:13: error: In procedure ‘ASCIIToUNICHAR’: unable
      to obtain the MIN value for type the ZType
        178 | END Unicode.
            |             ^
      Unicode.mod:178:13: error: unable to obtain the MAX value for type
      the ZType
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      
    Aside from the
      difference, and setting aside the question of why it is pointing
      to the end of the file rather then the location of the error, the
      error seems to stem from either the declaration of 'ASCIIRange',
      or the application of IN to same.
      
      The only reference to 'ZType' anywhere in the library source is a
      comment in SYSTEM.def, regarding the internal procedure 'SIZE()'.
      
      
      Can anyone familiar with the error explain what is actually
      happening here, please?