Handle C23 'b' format for scanf.

As with printf, the format checker expects 'b' to have its traditional ORCA/C behavior in pre-C23 modes, or the C23 standard behavior in C23 modes.

Also as with printf, it can detect when 'b' is being used in the traditional way and automatically change it to 'p'. Specifically, this is done when 'b' is used with no length modifier and the corresponding argument is a pointer to a character type. This behavior is controlled by the same #pragma extensions bit as for printf, and it also only works when the scanf-family function is called directly and has a string literal for the format string.

Printf.pas

@@ -469,6 +469,7 @@ var
       var
          expected: types;
          name: stringPtr;
+         argType: typePtr;
 
       begin {do_scanf_format}
 
@@ -476,7 +477,20 @@ var
 
       state := st_text;
       if c in format_set then begin
-
+         if c = 'b' then begin
+            if adjustFormat_b then
+               if has_length = default then begin
+                  argType := peekType;
+                  if argType <> nil then
+                     if argType^.kind in [pointerType,arrayType] then
+                        if argType^.ptype^.kind = scalarType then
+                           if argType^.ptype^.cType in [ctChar,ctUChar,ctSChar]
+                              then
+                              s^.str[i] := 'P';
+                  end;
+            if cStd < c23 then
+               c := 'P';
+            end; {if}
          case c of
 
             '%': begin
@@ -485,9 +499,9 @@ var
                has_suppress := true;
                end;
 
-            'b', 'P': begin
+            'P': begin
                if has_length <> default then
-                  Warning(@'length modifier may not be used with %b or %P');
+                  Warning(@'length modifier may not be used here');
                expected := [cgByte, cgUByte];
                name := @'char';
                end;
@@ -512,7 +526,7 @@ var
                if c = '[' then state := st_set_1;
                end;
 
-            'd', 'i', 'u', 'o', 'x', 'X': begin
+            'd', 'i', 'u', 'o', 'x', 'X', 'b': begin
                case has_length of
                   hh: begin
                      expected := [cgByte, cgUByte];