Index: generic/tclCompCmds.c
==================================================================
--- generic/tclCompCmds.c
+++ generic/tclCompCmds.c
@@ -299,11 +299,12 @@
     /*
      * Except for the special "ensure array" case below, when we're not in
      * a proc, we cannot do a better compile than generic.
      */
 
-    if (envPtr->procPtr == NULL && !(isDataEven && len == 0)) {
+    if ((varTokenPtr->type != TCL_TOKEN_SIMPLE_WORD) ||
+	    (envPtr->procPtr == NULL && !(isDataEven && len == 0))) {
 	code = TclCompileBasic2ArgCmd(interp, parsePtr, cmdPtr, envPtr);
 	goto done;
     }
 
     PushVarNameWord(interp, varTokenPtr, envPtr, TCL_NO_ELEMENT,
@@ -340,12 +341,13 @@
     if (localIndex < 0) {
 	/*
 	 * a non-local variable: upvar from a local one! This consumes the
 	 * variable name that was left at stacktop.
 	 */
-	
-	localIndex = AnonymousLocal(envPtr);
+
+	localIndex = TclFindCompiledLocal(varTokenPtr->start,
+		varTokenPtr->size, 1, envPtr);
 	PushStringLiteral(envPtr, "0");
 	TclEmitInstInt4(INST_REVERSE, 2,        		envPtr);
 	TclEmitInstInt4(INST_UPVAR, localIndex, 		envPtr);
 	TclEmitOpcode(INST_POP,          			envPtr);
     }

Index: generic/tclTrace.c
==================================================================
--- generic/tclTrace.c
+++ generic/tclTrace.c
@@ -2509,10 +2509,13 @@
     const char *part1, *part2;
 
     if (!part1Ptr) {
 	part1Ptr = localName(iPtr->varFramePtr, index);
     }
+    if (!part1Ptr) {
+	Tcl_Panic("Cannot trace a variable with no name");
+    }
     part1 = TclGetString(part1Ptr);
     part2 = part2Ptr? TclGetString(part2Ptr) : NULL;
 
     return TclCallVarTraces(iPtr, arrayPtr, varPtr, part1, part2, flags,
 	    leaveErrMsg);

Index: tests/var.test
==================================================================
--- tests/var.test
+++ tests/var.test
@@ -863,10 +863,21 @@
     apply {{} {
 	eval {array set ::x {}}
     }}
     array size x
 } -result 0
+test var-20.9 {[bc1a96407a] array set compiled w/ trace} {
+    variable foo
+    lappend lambda {}
+    lappend lambda [list array set [namespace which -variable foo] {a 1}]
+    after 0 [list apply $lambda]
+    vwait [namespace which -variable foo]
+    unset -nocomplain lambda foo
+} {}
+test var-20.10 {[bc1a96407a] array set don't compile bad varname} -body {
+    apply {{} {set name foo(bar); array set $name {a 1}}}
+} -returnCodes error -match glob -result *
 
 test var-21.0 {PushVarNameWord OBOE in compiled unset} -setup {
     proc linenumber {} {dict get [info frame -1] line}
 } -body {
     apply {n {