Index: generic/tclCompile.c
===================================================================
RCS file: /cvsroot/tcl/generic/tclCompile.c,v
retrieving revision 1.17
diff -c -r1.17 tclCompile.c
*** tclCompile.c	1999/10/21 02:16:22	1.17
--- tclCompile.c	1999/12/01 15:48:34
***************
*** 882,887 ****
--- 882,896 ----
  			    } else if (code == TCL_OUT_LINE_COMPILE) {
  				/* do nothing */
  			    } else { /* an error */
+  
+ 				/* Since there was a compilation error,
+ 				 * the last command did not get compiled
+ 				 * into (*envPtr).  We must decrement
+ 				 * the number of commands claimed to be
+ 				 * in (*envPtr).
+ 				 */
+ 
+ 				envPtr->numCommands--;
  				goto error;
  			    }
  			}
Index: tests/expr.test
===================================================================
RCS file: /cvsroot/tcl/tests/expr.test,v
retrieving revision 1.6
diff -c -r1.6 expr.test
*** expr.test	1999/08/19 03:00:13	1.6
--- expr.test	1999/12/01 15:48:37
***************
*** 711,716 ****
--- 711,719 ----
      set a yellow
      expr 1?{$a}:0
  } yellow
+ test expr-20.6 {handling of compile error in trial compile} {
+     list [catch {expr + {[incr]}} msg] $msg
+ } {1 {wrong # args: should be "incr varName ?increment?"}}
  
  # cleanup
  if {[info exists a]} {