3 files changed, 28 insertions, 8 deletions
diff --git a/eval.c b/eval.c
index 73efc9e3..e16e8075 100644
--- a/eval.c
+++ b/eval.c
@@ -1232,7 +1232,7 @@ static val bind_macro_params(val env, val menv, val params, val form,
     }
 
     if (consp(form)) {
-      if (optargs && car(form) == colon_k) {
+      if (optargs && opt_compat && opt_compat <= 190 && car(form) == colon_k) {
         form = cdr(form);
         goto noarg;
       }
diff --git a/share/txr/stdlib/place.tl b/share/txr/stdlib/place.tl
index d9fa60b3..6b4a1019 100644
--- a/share/txr/stdlib/place.tl
+++ b/share/txr/stdlib/place.tl
@@ -623,7 +623,7 @@
          (macrolet ((,getter () ^(cdr ,',entry-sym))
                     (,setter (val) ^(sys:rplacd ,',entry-sym ,val)))
             ,body))))
-  :
+  nil
   (deleter
     ^(macrolet ((,deleter ()
                   (if ,have-default-p
@@ -763,7 +763,7 @@
     ^(macrolet ((,getter () ^(fun ,',sym))
                 (,setter (val) ^(sys:setqf ,',sym ,val)))
        ,body))
-  :
+  nil
   (deleter
     ^(macrolet ((,deleter (:env env)
                    (when (lexical-fun-p env ',sym)
@@ -805,7 +805,7 @@
           (macrolet ((,getter () ^(call (car ,',gs-sym)))
                      (,setter (val) ^(call (cdr ,',gs-sym) ,val)))
             ,body))))
-  :
+  nil
   (deleter
     ^(macrolet ((,deleter () ^(fmakunbound ,',sym-expr)))
        ,body)))
@@ -821,7 +821,7 @@
           (macrolet ((,getter () ^(cdr ,',binding-sym))
                      (,setter (val) ^(sys:rplacd ,',binding-sym ,val)))
             ,body))))
-  :
+  nil
   (deleter
     ^(macrolet ((,deleter () ^(mmakunbound ,',sym-expr)))
        ,body)))
@@ -837,7 +837,7 @@
           (macrolet ((,getter () ^(cdr ,',binding-sym))
                      (,setter (val) ^(sys:rplacd ,',binding-sym ,val)))
             ,body))))
-  :
+  nil
   (deleter
     ^(macrolet ((,deleter () ^(makunbound ,',sym-expr)))
        ,body)))
diff --git a/txr.1 b/txr.1
index 443dedeb..6d6c5055 100644
--- a/txr.1
+++ b/txr.1
@@ -30454,6 +30454,19 @@ parameter inside has a restricted scope in a nested parameter
 list: its parameter will capture just that part of the argument material which
 matches that parameter list, rather than the entire argument list.
 
+The processing of macro parameter lists omits the feature that when the
+keyword symbol
+.code :
+(colon) given as the argument to an optional parameter, that argument is
+treated as a missing argument. This special logic is implemented only
+in the function argument passing mechanism, not in the binding of macro
+parameters to object structure. If the colon symbol appears in the object
+structure and is matched against an optional parameter, it is an
+ordinary value. That parameter is considered present, and takes on
+that
+.code :
+keyword symbol as its value.
+
 .TP* "Dialect Note:"
 
 In ANSI Common Lisp, the lambda list keyword
@@ -63254,8 +63267,15 @@ function neglected to perform
 initializations, and didn't invoke finalization on the structure object
 if an exception was thrown during reinitialization. Thus, contrary
 to documented requirements, reinitialization of a structure didn't behave
-like fresh construction.  This behavior is replicated if compatibility
-with 190 or earlier is requested.
+like fresh construction. Also, until \*(TX 190, macro parameter
+lists implemented the requirement that a
+.code :
+(colon keyword symbol) argument to an optional
+was treated as a missing argument, triggering argument-defaulting behavior.
+That requirement was removed; the colon symbol behaves as an ordinary value
+under destructuring with macro parameter lists.
+All these behaviors are restored in compatibility
+with version 190 or earlier.
 .IP 188
 Until \*(TX 188,
 .codn equal -based