Fix bug in map code that didn't handle substitutions efficiently (#1249)

* bug fix: find_subst_for_map() now returns a matching variable if it finds one

add a print statement so that option(prot) will indicate when find_subst_for_map() finds a substitution map

* add a test to verify bug fix in github PR 1249

* add test for github PR 1249 to ok_s.lst

Tst/Short/bug_pr1249.res.gz.uu

@@ -0,0 +1,9 @@
+begin 664 bug_pr1249.res.gz
+M'XL("#R&,F<"`V)U9U]P<C$R-#DN<F5S`%5006K#,!"\^Q5#Z$$&(2(G31J,
+M=0B]!$HOZ:T48Q,G+"BVD.36]NLKEV*UIUUF9G=VY_SV?'H%(!5>3D>LO/-"
+M4[W*D_,ODRD$L*26/$OS9*Y0"G5_*XV5V?8@VN9+.%_Y962CL/1;@<YXZEIF
+M;.?3N/=1P5AJO6X^&UW(761V?\;W`D%T@T6!-6<#'_F4\HN)ZB>%>V5P#0++
+M!SZ,$Y\B>P@NG1YA`CTNL%PKT*6I-.@_'F*X,@I7SBO)H8+K:^?)]_,+2?DN
+=/[email protected]>*K<B)^@YB1ZQV2:/R3?6ORBP%X!````
+`
+end

Tst/Short/bug_pr1249.stat

@@ -0,0 +1,4 @@
+1 >> tst_memory_0 :: 1731364412:44006, 64 bit:4.4.0:x86_64-Linux:edge:157192
+1 >> tst_memory_1 :: 1731364412:44006, 64 bit:4.4.0:x86_64-Linux:edge:2097152
+1 >> tst_memory_2 :: 1731364412:44006, 64 bit:4.4.0:x86_64-Linux:edge:2121864
+1 >> tst_timer_1 :: 1731364412:44006, 64 bit:4.4.0:x86_64-Linux:edge:9

Tst/Short/bug_pr1249.tst

@@ -0,0 +1,13 @@
+LIB "tst.lib";
+tst_init();
+
+option(prot);
+printlevel=16;
+
+ring r = 0,(x,y,z),dp;
+map f = r,x,xyz,z;
+poly p = y;
+ideal i = y;
+f(i);
+
+tst_status(1);$

Tst/Short/ok_s.lst

@@ -46,6 +46,7 @@ bug_ssi_algring
 bug_ssi_attr
 bug_subst
 bug_zp
+bug_pr1249
 bug_tr237
 ; do not try bug_tr276 without 2.2 GB RAM free
 bug_tr276

kernel/maps/gen_maps.cc

@@ -67,6 +67,7 @@ static void find_subst_for_map(const ring preimage_r, const ring image_r, const
         }
     }
   }
+  return;
   //Print("elms:%d, N:%d\n",IDELEMS(image),preimage_r->N);
   //iiWriteMatrix((matrix)image,"_",1,image_r,0);
   //PrintS("\npreimage:\n");rWrite(preimage_r);
@@ -107,6 +108,7 @@ ideal maMapIdeal(const ideal map_id, const ring preimage_r,const ideal image_id,
       find_subst_for_map(preimage_r,image_r,image_id,var,p);
       if (var!=0)
       {
+        if (TEST_OPT_PROT) PrintS("map is a substitution\n");
         return id_SubstPoly(map_id,var,p,preimage_r,image_r,nMap);
       }
     }