Add Info statement triggered when re-assigning already assigned attributes and the info level InfoAttributes is at least 3

lib/attr.gd

@@ -36,10 +36,14 @@
 ##  <InfoClass Name="InfoAttributes"/>
 ##
 ##  <Description>
-##  This info class (together with <Ref InfoClass="InfoWarning"/> is used
-##  for messages about attribute storing  being  disabled  (at  level  2)  or
-##  enabled (level 3). It may be  used  in  the  future  for  other  messages
-##  concerning changes to attribute behaviour.
+##  This info class (together with <Ref InfoClass="InfoWarning"/>) is used
+##  for messages about attributes. Messages are shown under the following circumstances:
+##  <List>
+##    <Item> <Ref Func="EnableAttributeValueStoring"/> is used (level 2).</Item>
+##    <Item> <Ref Func="DisableAttributeValueStoring"/> is used (level 3).</Item>
+##    <Item> When trying to assign to non-mutable attribute which already is set to a different value (level 3).</Item>
+##    <Item> When the test filter for an attribute (i.e., <C>HasFOO</C>) is set, but no value is assigned (level 3).</Item>
+##  </List>
 ##  </Description>
 ##  </ManSection>
 ##  <#/GAPDoc>

lib/attr.gi

@@ -37,3 +37,13 @@ InstallGlobalFunction(DisableAttributeValueStoring, function( attr )
     Info(InfoAttributes + InfoWarning, 2, "Disabling value storing for ",NAME_FUNC(attr));
     SET_ATTRIBUTE_STORING( attr, false);
 end);
+
+CHECK_REPEATED_ATTRIBUTE_SET := function(obj, name, val)
+    if InfoLevel(InfoAttributes) >= 3 then
+        if not IsBound(obj!.(name)) then
+            Info(InfoAttributes, 3, "Attribute ", name, " of ", obj, " is marked as assigned, but it has no value");
+        elif obj!.(name) <> val then
+            Info(InfoAttributes, 3, "Attribute ", name, " of ", obj, " already set to ", obj!.(name), ", cannot be changed to ", val);
+        fi;
+    fi;
+end;

lib/coll.gi

@@ -3105,13 +3105,7 @@ InstallOtherMethod(SetSize,true,[IsObject and IsAttributeStoringRep,IsObject],
 function(obj,sz)
 local filt;
   if HasSize(obj) and Size(obj)<>sz then
-    if AssertionLevel()>2 then
-      # Make this an ordinary error (not ErrorNoReturn as suggested) to
-      # preserve all debugging options -- even use `return` to investigate
-      # what would have happened before this methods was introduced.
-      Error("size of ",obj," already set to ",Size(obj),
-        ", cannot be changed to ",sz);
-    fi;
+    CHECK_REPEATED_ATTRIBUTE_SET(obj, "Size", sz);
     return;
   fi;
   if sz=0 then filt:=IsEmpty;

lib/module.gi

@@ -415,7 +415,7 @@ InstallOtherMethod(SetDimension,true,[IsObject and IsAttributeStoringRep,IsObjec
 function(obj,dim)
 local filt;
   if HasDimension(obj) and IsBound(obj!.Dimension) then
-    Assert(2, Dimension(obj) = dim);
+    CHECK_REPEATED_ATTRIBUTE_SET(obj, "Dimension", dim);
     return;
   fi;
   if dim=0 then

lib/oper1.g

@@ -1090,3 +1090,7 @@ InstallMethod( ViewObj,
     [ IS_OBJECT ],
     0,
     PRINT_OBJ );
+
+# A dummy version of this function is installed here, the full version
+# is defined in attr.gi, after Info-related functionality is set up.
+CHECK_REPEATED_ATTRIBUTE_SET := function(obj, name, val) end;

src/c_oper1.c

@@ -1,7 +1,7 @@
 #ifndef AVOID_PRECOMPILED
 /* C file produced by GAC */
 #include "compiled.h"
-#define FILE_CRC  "-77878372"
+#define FILE_CRC  "-76837766"
 
 /* global variables used in handlers */
 static GVar G_REREADING;
@@ -24,6 +24,7 @@ static GVar G_SET__NAME__FUNC;
 static Obj  GF_SET__NAME__FUNC;
 static GVar G_NARG__FUNC;
 static Obj  GF_NARG__FUNC;
+static GVar G_CHECK__REPEATED__ATTRIBUTE__SET;
 static GVar G_IS__OPERATION;
 static Obj  GF_IS__OPERATION;
 static GVar G_AINV;
@@ -181,7 +182,7 @@ static RNam R_CommandLineOptions;
 static RNam R_N;
 
 /* information for the functions */
-static Obj  NameFunc[19];
+static Obj  NameFunc[20];
 static Obj FileName;
 
 /* handler for function 2 */
@@ -5184,6 +5185,27 @@ static Obj  HdlrFunc17 (
  return 0;
 }
 
+/* handler for function 19 */
+static Obj  HdlrFunc19 (
+ Obj  self,
+ Obj  a_obj,
+ Obj  a_name,
+ Obj  a_val )
+{
+ Bag oldFrame;
+
+ /* allocate new stack frame */
+ SWITCH_TO_NEW_FRAME(self,0,0,oldFrame);
+
+ /* return; */
+ SWITCH_TO_OLD_FRAME(oldFrame);
+ return 0;
+
+ /* return; */
+ SWITCH_TO_OLD_FRAME(oldFrame);
+ return 0;
+}
+
 /* handler for function 1 */
 static Obj  HdlrFunc1 (
  Obj  self )
@@ -5907,6 +5929,18 @@ static Obj  HdlrFunc1 (
   DoOperation2Args( CallFuncListOper, t_1, NewPlistFromArgs( t_2, t_3, t_4, t_5, INTOBJ_INT(0), t_6 ) );
  }
 
+ /* CHECK_REPEATED_ATTRIBUTE_SET := function ( obj, name, val )
+      return;
+  end; */
+ t_1 = NewFunction( NameFunc[19], 3, ArgStringToList("obj,name,val"), HdlrFunc19 );
+ SET_ENVI_FUNC( t_1, STATE(CurrLVars) );
+ t_2 = NewFunctionBody();
+ SET_STARTLINE_BODY(t_2, 1096);
+ SET_ENDLINE_BODY(t_2, 1096);
+ SET_FILENAME_BODY(t_2, FileName);
+ SET_BODY_FUNC(t_1, t_2);
+ AssGVar( G_CHECK__REPEATED__ATTRIBUTE__SET, t_1 );
+
  /* return; */
  SWITCH_TO_OLD_FRAME(oldFrame);
  return 0;
@@ -5931,6 +5965,7 @@ static Int PostRestore ( StructInitInfo * module )
  G_NAME__FUNC = GVarName( "NAME_FUNC" );
  G_SET__NAME__FUNC = GVarName( "SET_NAME_FUNC" );
  G_NARG__FUNC = GVarName( "NARG_FUNC" );
+ G_CHECK__REPEATED__ATTRIBUTE__SET = GVarName( "CHECK_REPEATED_ATTRIBUTE_SET" );
  G_IS__OPERATION = GVarName( "IS_OPERATION" );
  G_AINV = GVarName( "AINV" );
  G_IS__INT = GVarName( "IS_INT" );
@@ -6031,6 +6066,7 @@ static Int PostRestore ( StructInitInfo * module )
  NameFunc[16] = 0;
  NameFunc[17] = 0;
  NameFunc[18] = 0;
+ NameFunc[19] = 0;
 
  /* return success */
  return 0;
@@ -6167,6 +6203,8 @@ static Int InitKernel ( StructInitInfo * module )
  InitGlobalBag( &(NameFunc[17]), "GAPROOT/lib/oper1.g:NameFunc[17]("FILE_CRC")" );
  InitHandlerFunc( HdlrFunc18, "GAPROOT/lib/oper1.g:HdlrFunc18("FILE_CRC")" );
  InitGlobalBag( &(NameFunc[18]), "GAPROOT/lib/oper1.g:NameFunc[18]("FILE_CRC")" );
+ InitHandlerFunc( HdlrFunc19, "GAPROOT/lib/oper1.g:HdlrFunc19("FILE_CRC")" );
+ InitGlobalBag( &(NameFunc[19]), "GAPROOT/lib/oper1.g:NameFunc[19]("FILE_CRC")" );
 
  /* return success */
  return 0;
@@ -6201,7 +6239,7 @@ static Int InitLibrary ( StructInitInfo * module )
 static StructInitInfo module = {
  .type        = MODULE_STATIC,
  .name        = "GAPROOT/lib/oper1.g",
- .crc         = -77878372,
+ .crc         = -76837766,
  .initKernel  = InitKernel,
  .initLibrary = InitLibrary,
  .postRestore = PostRestore,

src/hpc/c_oper1.c

@@ -1,7 +1,7 @@
 #ifndef AVOID_PRECOMPILED
 /* C file produced by GAC */
 #include "compiled.h"
-#define FILE_CRC  "-77878372"
+#define FILE_CRC  "-76837766"
 
 /* global variables used in handlers */
 static GVar G_REREADING;
@@ -24,6 +24,7 @@ static GVar G_SET__NAME__FUNC;
 static Obj  GF_SET__NAME__FUNC;
 static GVar G_NARG__FUNC;
 static Obj  GF_NARG__FUNC;
+static GVar G_CHECK__REPEATED__ATTRIBUTE__SET;
 static GVar G_IS__OPERATION;
 static Obj  GF_IS__OPERATION;
 static GVar G_AINV;
@@ -197,7 +198,7 @@ static RNam R_CommandLineOptions;
 static RNam R_N;
 
 /* information for the functions */
-static Obj  NameFunc[19];
+static Obj  NameFunc[20];
 static Obj FileName;
 
 /* handler for function 2 */
@@ -5309,6 +5310,27 @@ static Obj  HdlrFunc17 (
  return 0;
 }
 
+/* handler for function 19 */
+static Obj  HdlrFunc19 (
+ Obj  self,
+ Obj  a_obj,
+ Obj  a_name,
+ Obj  a_val )
+{
+ Bag oldFrame;
+
+ /* allocate new stack frame */
+ SWITCH_TO_NEW_FRAME(self,0,0,oldFrame);
+
+ /* return; */
+ SWITCH_TO_OLD_FRAME(oldFrame);
+ return 0;
+
+ /* return; */
+ SWITCH_TO_OLD_FRAME(oldFrame);
+ return 0;
+}
+
 /* handler for function 1 */
 static Obj  HdlrFunc1 (
  Obj  self )
@@ -6052,6 +6074,18 @@ static Obj  HdlrFunc1 (
   DoOperation2Args( CallFuncListOper, t_1, NewPlistFromArgs( t_2, t_3, t_4, t_5, INTOBJ_INT(0), t_6 ) );
  }
 
+ /* CHECK_REPEATED_ATTRIBUTE_SET := function ( obj, name, val )
+      return;
+  end; */
+ t_1 = NewFunction( NameFunc[19], 3, ArgStringToList("obj,name,val"), HdlrFunc19 );
+ SET_ENVI_FUNC( t_1, STATE(CurrLVars) );
+ t_2 = NewFunctionBody();
+ SET_STARTLINE_BODY(t_2, 1096);
+ SET_ENDLINE_BODY(t_2, 1096);
+ SET_FILENAME_BODY(t_2, FileName);
+ SET_BODY_FUNC(t_1, t_2);
+ AssGVar( G_CHECK__REPEATED__ATTRIBUTE__SET, t_1 );
+
  /* return; */
  SWITCH_TO_OLD_FRAME(oldFrame);
  return 0;
@@ -6076,6 +6110,7 @@ static Int PostRestore ( StructInitInfo * module )
  G_NAME__FUNC = GVarName( "NAME_FUNC" );
  G_SET__NAME__FUNC = GVarName( "SET_NAME_FUNC" );
  G_NARG__FUNC = GVarName( "NARG_FUNC" );
+ G_CHECK__REPEATED__ATTRIBUTE__SET = GVarName( "CHECK_REPEATED_ATTRIBUTE_SET" );
  G_IS__OPERATION = GVarName( "IS_OPERATION" );
  G_AINV = GVarName( "AINV" );
  G_IS__INT = GVarName( "IS_INT" );
@@ -6184,6 +6219,7 @@ static Int PostRestore ( StructInitInfo * module )
  NameFunc[16] = 0;
  NameFunc[17] = 0;
  NameFunc[18] = 0;
+ NameFunc[19] = 0;
 
  /* return success */
  return 0;
@@ -6328,6 +6364,8 @@ static Int InitKernel ( StructInitInfo * module )
  InitGlobalBag( &(NameFunc[17]), "GAPROOT/lib/oper1.g:NameFunc[17]("FILE_CRC")" );
  InitHandlerFunc( HdlrFunc18, "GAPROOT/lib/oper1.g:HdlrFunc18("FILE_CRC")" );
  InitGlobalBag( &(NameFunc[18]), "GAPROOT/lib/oper1.g:NameFunc[18]("FILE_CRC")" );
+ InitHandlerFunc( HdlrFunc19, "GAPROOT/lib/oper1.g:HdlrFunc19("FILE_CRC")" );
+ InitGlobalBag( &(NameFunc[19]), "GAPROOT/lib/oper1.g:NameFunc[19]("FILE_CRC")" );
 
  /* return success */
  return 0;
@@ -6362,7 +6400,7 @@ static Int InitLibrary ( StructInitInfo * module )
 static StructInitInfo module = {
  .type        = MODULE_STATIC,
  .name        = "GAPROOT/lib/oper1.g",
- .crc         = -77878372,
+ .crc         = -76837766,
  .initKernel  = InitKernel,
  .initLibrary = InitLibrary,
  .postRestore = PostRestore,

src/opers.c

@@ -1385,6 +1385,7 @@ static UInt RNamIsVerbose;
 static UInt RNamIsConstructor;
 static UInt RNamPrecedence;
 static Obj  HANDLE_METHOD_NOT_FOUND;
+static Obj  CHECK_REPEATED_ATTRIBUTE_SET;
 
 static void HandleMethodNotFound(Obj   oper,
                                  Int   nargs,
@@ -3283,12 +3284,15 @@ static Obj DoSetterFunction(Obj self, Obj obj, Obj value)
     flag2  = INT_INTOBJ( FLAG2_FILT(tester) );
     type   = TYPE_OBJ_FEO(obj);
     flags  = FLAGS_TYPE(type);
+
+    UInt rnam = (UInt)INT_INTOBJ(ELM_PLIST(tmp, 1));
+
     if ( SAFE_C_ELM_FLAGS(flags,flag2) ) {
+        CALL_3ARGS(CHECK_REPEATED_ATTRIBUTE_SET, obj, NAME_RNAM(rnam), value);
         return 0;
     }
 
     /* set the value                                                       */
-    UInt rnam = (UInt)INT_INTOBJ(ELM_PLIST(tmp,1));
 #ifdef HPCGAP
     if (atomic)
       SetARecordField( obj, rnam, CopyObj(value,0) );
@@ -3772,6 +3776,9 @@ static Int InitKernel (
     ImportFuncFromLibrary("HANDLE_METHOD_NOT_FOUND",
                           &HANDLE_METHOD_NOT_FOUND);
 
+    ImportFuncFromLibrary("CHECK_REPEATED_ATTRIBUTE_SET",
+                          &CHECK_REPEATED_ATTRIBUTE_SET);
+
 #ifdef GASMAN
     ImportGVarFromLibrary( "IsType", &IsType );
     ImportFuncFromLibrary( "FLUSH_ALL_METHOD_CACHES", &FLUSH_ALL_METHOD_CACHES );

tst/testinstall/attribute.tst

@@ -1,4 +1,6 @@
 gap> START_TEST("attribute.tst");
+gap> attributeinfo := InfoLevel(InfoAttributes);;
+gap> SetInfoLevel(InfoAttributes, 3);
 gap> DeclareAttribute();
 Error, Function: number of arguments must be at least 2 (not 0)
 gap> DeclareAttribute("banana");
@@ -60,6 +62,19 @@ gap> HasSize(foo);
 true
 gap> Size(foo);
 17
+gap> SetSize(foo, 16);
+#I  Attribute Size of <object> already set to 17, cannot be changed to 16
+gap> Size(foo);
+17
+gap> HasDimension(foo);
+false
+gap> SetDimension(foo, 3);
+gap> HasDimension(foo);
+true
+gap> SetDimension(foo, 4);
+#I  Attribute Dimension of <object> already set to 3, cannot be changed to 4
+gap> Dimension(foo);
+3
 gap> InstallMethod(FavouriteFruit, [HasSize], x-> "pear");
 gap> FavouriteFruit(foo);
 "pear"
@@ -70,5 +85,22 @@ gap> FavouriteFruit(foo);
 "pear"
 gap> HasFavouriteFruit(foo);
 true
+gap> SetFavouriteFruit(foo, "apple");
+#I  Attribute FavouriteFruit of <object> already set to pear, cannot be changed to apple
+gap> FavouriteFruit(foo);
+"pear"
+gap> Unbind(foo!.FavouriteFruit);
+gap> SetFavouriteFruit(foo, "apple");
+#I  Attribute FavouriteFruit of <object> is marked as assigned, but it has no value
 #@fi
+
+# Check a mutable attribute
+gap> grp := Group(());;
+gap> SetStabChainMutable(grp, [1,2]);
+gap> StabChainMutable(grp);
+[ 1, 2 ]
+gap> SetStabChainMutable(grp, [3,4]);
+gap> StabChainMutable(grp);
+[ 3, 4 ]
+gap> SetInfoLevel(InfoAttributes, attributeinfo);
 gap> STOP_TEST("attribute.tst", 1);