When tracing immediates, print location of definition

For now, we print the location of the *method*. Ideally, we should
instead track the location of the InstallImmediateMethod call. See also
issue #2239.

Before:

    gap> TraceImmediateMethods( );
    gap> g:= Group( (1,2,3), (1,2) );;
    #I  immediate: Size
    #I  immediate: IsCyclic
    #I  immediate: IsCommutative
    #I  immediate: IsTrivial

After:

    gap> TraceImmediateMethods( );
    gap> g:= Group( (1,2,3), (1,2) );;
    #I RunImmediateMethods
    #I  immediate: Size at GAPROOT/lib/coll.gi:174
    #I  immediate: IsCyclic at GAPROOT/lib/grp.gi:34
    #I  immediate: IsCommutative at GAPROOT/lib/magma.gi:190
    #I  immediate: IsTrivial at GAPROOT/lib/magma.gi:124

Author: fingolfin

lib/oper.g

@@ -554,9 +554,10 @@ end );
 ##  <Ref Func="UntraceImmediateMethods"/>, or <Ref Func="TraceImmediateMethods"/>
 ##  with <A>flag</A> equal <K>false</K> turns tracing off.
 ##  (There is no facility to trace <E>specific</E> immediate methods.)
-##  <Example><![CDATA[
+##  <Log><![CDATA[
 ##  gap> TraceImmediateMethods( );
 ##  gap> g:= Group( (1,2,3), (1,2) );;
+##  #I RunImmediateMethods
 ##  #I  immediate: Size
 ##  #I  immediate: IsCyclic
 ##  #I  immediate: IsCommutative
@@ -574,7 +575,7 @@ end );
 ##  6
 ##  gap> UntraceImmediateMethods( );
 ##  gap> UntraceMethods( [ Size ] );
-##  ]]></Example>
+##  ]]></Log>
 ##  <P/>
 ##  This example gives an explanation for the two calls of the
 ##  <Q>system getter</Q> for <Ref Func="Size"/>.

lib/oper1.g

@@ -20,6 +20,7 @@
 ##  have been discovered recently.
 ##  So possible consequences of other filters are not checked.
 ##
+RUN_IMMEDIATE_METHODS_RUNS   := 0;
 RUN_IMMEDIATE_METHODS_CHECKS := 0;
 RUN_IMMEDIATE_METHODS_HITS   := 0;
 
@@ -31,7 +32,9 @@ BIND_GLOBAL( "RunImmediateMethods", function ( obj, flags )
             j,          # loop over `flagspos'
             imm,        # immediate methods for filter `j'
             i,          # loop over `imm'
+            meth,
             res,        # result of an immediate method
+            loc,
             newflags;   # newly  found filters
 
     # Avoid recursive calls from inside a setter,
@@ -49,6 +52,11 @@ BIND_GLOBAL( "RunImmediateMethods", function ( obj, flags )
     type     := TYPE_OBJ( obj );
     flags    := type![2];
 
+    RUN_IMMEDIATE_METHODS_RUNS := RUN_IMMEDIATE_METHODS_RUNS + 1;
+    if TRACE_IMMEDIATE_METHODS  then
+        Print( "#I RunImmediateMethods\n");
+    fi;
+
     # Check the immediate methods for all in `flagspos'.
     # (Note that new information is handled via appending to that list.)
     for j  in flagspos  do
@@ -71,16 +79,26 @@ BIND_GLOBAL( "RunImmediateMethods", function ( obj, flags )
                 then
 
                     # Call the method, and store that it was used.
-                    res := IMMEDIATE_METHODS[ imm[i+6] ]( obj );
+                    meth := IMMEDIATE_METHODS[ imm[i+6] ];
+                    res := meth( obj );
                     ADD_LIST( tried, imm[i+6] );
                     RUN_IMMEDIATE_METHODS_CHECKS :=
                         RUN_IMMEDIATE_METHODS_CHECKS+1;
                     if TRACE_IMMEDIATE_METHODS  then
-                        if imm[i+7] = false then
-                            Print( "#I  immediate: ", NAME_FUNC( imm[i+1] ), "\n");
-                        else
-                            Print( "#I  immediate: ", NAME_FUNC( imm[i+1] ), ": ", imm[i+7], "\n" );
+                        Print( "#I  immediate: ", NAME_FUNC( imm[i+1] ));
+                        if imm[i+7] <> false then
+                            Print( ": ", imm[i+7] );
+                        fi;
+                        if IsBound(LocationFunc) then
+                            loc := VALUE_GLOBAL("LocationFunc")( meth );
+                            if loc <> "" then
+                                Print(" at ", loc);
+                            fi;
+                        fi;
+                        if NAME_FUNC(meth) <> "unknown" then
+                            Print(" via ", NAME_FUNC(meth));
                         fi;
+                        Print("\n");
                     fi;
 
                     if res <> TRY_NEXT_METHOD  then