[Ada] Diagnostics in Elaboration order v4.0

This patch introduces several changes to the new elaboration order
mechanism:

  * The library graph can now discover, store, and organize the various
    cycles it contains.

  * The elaboration order mechanism can now diagnose one or all cycles
    within the library graph. Diagnostics consist of describing the
    reason for the cycle, listing all units comprising the circuit, and
    offering suggestions on how to break the cycle.

The patch also modifies unit ALI to hide all invocation-related data
structures and several implementation-specific types by relocating them
in the body of the unit.

The patch cleans up most children of Bindo by using better names of
routines and formal parameters.

------------
-- Source --
------------

--  a.ads

with B; pragma Elaborate_All (B);
with C; pragma Elaborate_All (C);

package A is
end A;

--  b.ads

package B is
   procedure Force_Body;
end B;

--  b.adb

with D;

package body B is
   procedure Force_Body is null;

   Elab : constant Integer := D.Func;
end B;

--  c.ads

package C is
   procedure Force_Body;
end C;

--  c.adb

with E;

package body C is
   procedure Force_Body is null;
end C;

--  d.ads

package D is
   function Func return Integer;
end D;

--  d.adb

with A;

package body D is
   Local : Integer := 123;

   function Func return Integer is
   begin
      return Local;
   end Func;
end D;

--  e.ads

with A;

package E is
end E;

--  main.adb

with B;

--             Elaborate_All             Elaborate_All               with
--    C spec <--------------- A spec ---------------------> B spec <------ Main
--      ^                      ^  ^                           ^
--      |                      |  |                           |
--  sbb |                      |  |                           | sbb
--      |                      |  |                           |
--    C body -----------> E spec  |       D spec <--------- B body
--               with             |         ^       with      |
--                                |         |                 |
--                                |     sbb |                 |
--                                |         |                 |
--                                +------ D body <------------+
--                                  with           Invocation
--
--  The cycles are
--
--    A spec --> C spec --> E spec --> A spec
--               C body
--
--    A spec --> B spec --> D body --> A spec
--               B body

procedure Main is begin null; end Main;

----------------------------
-- Compilation and output --
----------------------------

$ gnatmake -q main.adb -bargs -d_C -d_N
error: Elaboration circularity detected
info:
info:    Reason:
info:
info:      unit "a (spec)" depends on its own elaboration
info:
info:    Circularity:
info:
info:      unit "a (spec)" has with clause and pragma Elaborate_All for unit
             "b (spec)"
info:      unit "b (body)" is in the closure of pragma Elaborate_All
info:      unit "b (body)" has with clause for unit "d (spec)"
info:      unit "d (body)" is in the closure of pragma Elaborate_All
info:      unit "d (body)" has with clause for unit "a (spec)"
info:
info:    Suggestions:
info:
info:      change pragma Elaborate_All for unit "b (spec)" to Elaborate in unit
             "a (spec)"
info:      remove pragma Elaborate_All for unit "b (spec)" in unit "a (spec)"
info:
error: Elaboration circularity detected
info:
info:    Reason:
info:
info:      unit "a (spec)" depends on its own elaboration
info:
info:    Circularity:
info:
info:      unit "a (spec)" has with clause and pragma Elaborate_All for unit
             "c (spec)"
info:      unit "c (body)" is in the closure of pragma Elaborate_All
info:      unit "c (body)" has with clause for unit "e (spec)"
info:      unit "e (spec)" has with clause for unit "a (spec)"
info:
info:    Suggestions:
info:
info:      change pragma Elaborate_All for unit "c (spec)" to Elaborate in unit
             "a (spec)"
info:      remove pragma Elaborate_All for unit "c (spec)" in unit "a (spec)"
info:
gnatmake: *** bind failed.

2019-07-05  Hristian Kirtchev  <kirtchev@adacore.com>

gcc/ada/

	* ali.adb: Relocate types Invocation_Construct_Record,
	Invocation_Relation_Record, and Invocation_Signature_Record to
	the body of ALI.  Relocate tables Invocation_Constructs,
	Invocation_Relations, and Invocation_Signatures to the body of
	ALI.  Remove type Body_Placement_Codes.  Add new types
	Declaration_Placement_Codes, and
	Invocation_Graph_Encoding_Codes.  Update the literals of type
	Invocation_Graph_Line_Codes.
	(Add_Invocation_Construct): Update the parameter profile. Add an
	invocation construct built from all attributes provided.
	(Add_Invocation_Relation): Update the parameter profile. Add an
	invocation relation built from all attributes provided.
	(Body_Placement): New routine.
	(Body_Placement_Kind_To_Code, Code_To_Body_Placement_Kind):
	Removed.
	(Code_To_Declaration_Placement_Kind,
	Code_To_Invocation_Graph_Encoding_Kind, Column,
	Declaration_Placement_Kind_To_Code, Extra,
	For_Each_Invocation_Construct, For_Each_Invocation_Relation,
	Invocation_Graph_Encoding,
	Invocation_Graph_Encoding_Kind_To_Code, Invoker, Kind, Line,
	Locations, Name): New routine.
	(Scan_Invocation_Construct_Line): Reimplement the scanning
	mechanism.
	(Scan_Invocation_Graph_Attributes_Line): New routine.
	(Scan_Invocation_Graph_Line): Use a case statement to dispatch.
	(Scan_Invocation_Relation_Line): Reimplement the scanning
	mechanism.
	(Scope): New routine.
	(Set_Invocation_Graph_Encoding, Signature, Spec_Placement,
	Target): New routine.
	* ali.ads: Add new type Invocation_Graph_Encoding_Kind.  Add
	component Invocation_Graph_Encoding to type Unit_Record.
	Relocate various types and data structures to the body of ALI.
	(Add_Invocation_Construct, Add_Invocation_Relation): Update the
	parameter profile.
	(Body_Placement): New routine.
	(Body_Placement_Kind_To_Code, Code_To_Body_Placement_Kind):
	Removed.
	(Code_To_Declaration_Placement_Kind,
	Code_To_Invocation_Graph_Encoding_Kind, Column,
	Declaration_Placement_Kind_To_Code, Extra,
	For_Each_Invocation_Construct, For_Each_Invocation_Relation,
	Invocation_Graph_Encoding,
	Invocation_Graph_Encoding_Kind_To_Code, Invoker, Kind, Line,
	Locations, Name, Scope, Set_Invocation_Graph_Encoding,
	Signature, Spec_Placement, Target): New routine.
	* bindo.adb: Add with clause for Binde.  Add with and use
	clauses for Debug.  Update the documentation.  Add new switches.
	(Find_Elaboration_Order): Dispatch to the proper elaboration
	mechanism.
	* bindo-augmentors.adb:
	Remove with and use clauses for GNAT and GNAT.Sets.  Remove
	membership set VS.  Update the parameter profiles of most
	routines to use better parameter names.  Update the
	implementation of most routine to use the new parameter names.
	Remove various redundant assertions.
	* bindo-builders.adb: Use better names for instantiated data
	structures. Update all references to these names.  Update the
	parameter profiles of most routines to use better parameter
	names.  Update the implementation of most routine to use the new
	parameter names.
	(Build_Library_Graph): Update the parameter profile. Update the
	call to Create.
	(Create_Vertex): Reimplemented.
	(Declaration_Placement_Vertex): New routine.
	* bindo-builders.ads (Build_Library_Graph): Update the parameter
	profile and comment on usage.
	* bindo-diagnostics.adb: Almost a new unit.
	* bindo-diagnostics.ads: Add a use clause for
	Bindo.Graphs.Invocation_Graphs.  Remove package
	Cycle_Diagnostics.
	(Diagnose_Circularities): New routine.
	* bindo-elaborators.adb: Remove the with and use clauses for
	Binderr and GNAT.Sets.  Remove the use clause for
	Bindo.Diagnostics.Cycle_Diagnostics.  Remove membership set VS.
	Update the parameter profiles of most routines to use better
	parameter names.  Update the implementation of most routine to
	use the new parameter names.  (Elaborate_Units_Common): Update
	the parameter profile. Pass an infication to the library graph
	builder whether the dynamic model is in effect.
	(Elaborate_Units_Dynamic, Elaborate_Units_Static): Use
	Diagnose_Circularities to provide diagnostics.
	(Update_Successor): Use routine In_Same_Component to determine
	whether the predecessor and successor reside in different
	components.
	* bindo-graphs.adb: Add with and use clauses for Butil, Debug,
	Output, and Bindo.Writers.  Remove with and use clauses for
	GNAT.Lists.  Update the parameter profiles of most routines to
	use better parameter names.  Update the implementation of most
	routine to use the new parameter names.  Remove various
	redundant assertions.  Remove doubly linked list EL.  Add new
	type Precedence_Kind.
	(Add_Cycle): New routine.
	(Add_Vertex): Update the parameter profile. Update the creation
	of vertex attributes.
	(Add_Vertex_And_Complement, Body_Vertex, Column,
	Complementary_Vertex, Copy_Cycle_Path, Cycle_Kind_Of): New
	routines.
	(Destroy_Invocation_Graph_Edge, Destroy_Library_Graph_Cycle,
	Destroy_Library_Graph_Edge, Extra, File_Name,
	Find_All_Cycles_Through_Vertex, Find_All_Cycles_With_Edge,
	Find_Cycles, Find_First_Lower_Precedence_Cycle,
	Get_LGC_Attributes, Has_Next, Hash_Library_Graph_Cycle,
	Hash_Library_Graph_Cycle_Attributes, Highest_Precedence_Cycle,
	Highest_Precedence_Edge, In_Same_Component, Insert_And_Sort,
	Invocation_Edge_Count, Invocation_Graph_Encoding,
	Is_Cycle_Initiating_Edge, Is_Cyclic_Edge,
	Is_Cyclic_Elaborate_All_Edge, Is_Cyclic_Elaborate_Body_Edge,
	Is_Cyclic_Elaborate_Edge, Is_Cyclic_Forced_Edge,
	Is_Cyclic_Invocation_Edge, Is_Cyclic_With_Edge,
	Is_Dynamically_Elaborated, Is_Elaborate_All_Edge,
	Is_Elaborate_Body_Edge, Is_Elaborate_Edge: New routines.
	(Is_Existing_Predecessor_Successor_Relation): Removed.
	(Is_Forced_Edge, Is_Invocation_Edge, Is_Recorded_Cycle,
	Is_Recorded_Edge, Is_With_Edge, Iterate_Edges_Of_Cycle, Kind,
	Length): New routine.
	(Lib_Vertex): Removed.
	(Line, Links_Vertices_In_Same_Component,
	Maximum_Invocation_Edge_Count, Next, Normalize_And_Add_Cycle,
	Normalize_Cycle_Path, Number_Of_Cycles, Path, Precedence,
	Remove_Vertex_And_Complement, Sequence_Next_Cycle): New routines.
	(Sequence_Next_IGE_Id): Renamed to Sequence_Next_Edge.
	(Sequence_Next_IGV_Id): Renamed to Sequence_Next_Vertex.
	(Sequence_Next_LGE_Id): Renamed to Sequence_Next_Edge.
	(Sequence_Next_LGV_Id): Renamed to Sequence_Next_Vertex.
	(Set_Is_Existing_Predecessor_Successor_Relation): Removed.
	(Set_Is_Recorded_Cycle, Set_Is_Recorded_Edge,
	Set_LGC_Attributes, Spec_Vertex, Trace_Cycle, Trace_Edge,
	Trace_Eol, Trace_Vertex): New routines.
	* bindo-graphs.ads: Add with and use clauses for Types and
	GNAT.Lists.  Update the parameter profiles of most routines to
	use better parameter names.  Update the implementation of most
	routine to use the new parameter names.  Add the new
	instantiated data structures IGE_Lists, IGV_Sets, LGC_Lists,
	LGE_Lists, LGE_Sets, LGV_Sets, and RC_Sets.  Add new type
	Library_Graph_Cycle_Id along with an empty and initial value.
	Remove component Lib_Vertex and add new components Body_Vertex
	and Spec_Vertex to type Invocation_Graph_Vertex_Attributes.  Add
	new type Library_Graph_Cycle_Kind.  Add new iterators
	All_Cycle_Iterator and Edges_Of_Cycle_Iterator.  Add new type
	Library_Graph_Cycle_Attributes.  Add new components
	Cycle_Attributes, Cycles, and Dynamically_Elaborated to type
	Library_Graph_Attributes.
	(Body_Vertex, Column, Destroy_Invocation_Graph_Edge,
	Destroy_Library_Graph_Cycle_Attributes,
	Destroy_Library_Graph_Edge, Extra, File_Name, Find_Cycles,
	Has_Elaborate_All_Cycle, Has_Next, Hash_Library_Graph_Cycle,
	Hash_Library_Graph_Cycle_Attributes, Highest_Precedence_Cycle,
	In_Same_Component, Invocation_Edge_Count,
	Invocation_Graph_Encoding, Is_Dynamically_Elaborated,
	Is_Elaborate_All_Edge, Is_Elaborate_Body_Edge,
	Is_Elaborate_Edge, Is_Forced_Edge, Is_Invocation_Edge,
	Is_With_Edge, Iterate_All_Cycles, Iterate_Edges_Of_Cycle, Kind):
	New routines.
	(Length, Lib_Vertex, (Line, Next, Number_Of_Cycles, Present,
	Same_Library_Graph_Cycle_Attributes, Spec_Vertex): New routines.
	* bindo-units.adb (File_Name, Invocation_Graph_Encoding): New
	routines.
	* bindo-units.ads: Add new instantiated data structure
	Unit_Sets.
	(File_Name, Invocation_Graph_Encoding): New routine.
	* bindo-validators.adb: Remove with and use clauses for GNAT and
	GNAT.Sets.  Remove membership set US.  Update the parameter
	profiles of most routines to use better parameter names.  Update
	the implementation of most routine to use the new parameter
	names.
	(Validate_Cycle, Validate_Cycle_Path, Validate_Cycles,
	Validate_Invocation_Graph_Vertex): Remove the validation of
	component Lib_Vertex. Add the validation of components
	Body_Vertex and Spec_Vertex.
	(Write_Error): New routine.
	* bindo-validators.ads (Validate_Cycles): New routine.
	* bindo-writers.adb: Update the parameter profiles of most
	routines to use better parameter names.  Update the
	implementation of most routine to use the new parameter names.
	(Write_Cycle, Write_Cyclic_Edge, Write_Cycles): New routines.
	(Write_Invocation_Graph_Vertex): Remove the output of component
	Lib_Vertex. Add the output of components Body_Vertex and
	Spec_Vertex.
	* bindo-writers.ads (Write_Cycles): New routine.
	* debug.adb: Use binder switches -d_C and -d_P, add
	documentation on their usage.
	* gnatbind.adb: Remove with and use clauses for Binde.  Delegate
	the choice of elaboration mechanism to Bindo.
	* lib-writ.adb (Column, Extra, Invoker, Kind, Line, Locations,
	Name, Placement, Scope, Signature, Target): Removed.
	(Write_Invocation_Graph): Moved at the top level.
	(Write_Invocation_Graph_Attributes): New routine.
	(Write_Invocation_Relation, Write_Invocation_Signature): Moved
	at the top level.
	* lib-writ.ads: Add a documentation section on invocation graph
	attributes.
	* sem_elab.adb (Body_Placement_Of): New routine.
	(Declare_Invocation_Construct): Update the call to
	Add_Invocation_Construct.
	(Declaration_Placement_Of_Node): New routine.
	(Get_Invocation_Attributes): Correct the retrieval of the
	enclosing subprogram where the postcondition procedure lives.
	(Placement_Of, Placement_Of_Node): Removed.
	(Record_Invocation_Graph): Record the encoding format used.
	(Record_Invocation_Graph_Encoding): New routine.
	(Record_Invocation_Relation): Update the call to
	Add_Invocation_Relation.
	(Spec_Placement_Of): Removed.
	* libgnat/g-lists.ads, libgnat/g-lists.adb (Equal): New routine.

From-SVN: r273107

1 files changed, 111 insertions, 118 deletions

diff --git a/gcc/ada/bindo-builders.adb b/gcc/ada/bindo-builders.adb
index c0340c0..f4b8e42 100644
--- a/gcc/ada/bindo-builders.adb
+++ b/gcc/ada/bindo-builders.adb
@@ -64,10 +64,10 @@ package body Bindo.Builders is
 
       procedure Create_Vertex
         (IC_Id  : Invocation_Construct_Id;
-         LGV_Id : Library_Graph_Vertex_Id);
+         Vertex : Library_Graph_Vertex_Id);
       pragma Inline (Create_Vertex);
       --  Create a new vertex for invocation construct IC_Id in invocation
-      --  graph Inv_Graph. The vertex is linked to vertex LGV_Id of library
+      --  graph Inv_Graph. The vertex is linked to vertex Vertex of library
       --  graph Lib_Graph.
 
       procedure Create_Vertices (U_Id : Unit_Id);
@@ -75,6 +75,14 @@ package body Bindo.Builders is
       --  Create new vertices for all invocation constructs of unit U_Id in
       --  invocation graph Inv_Graph.
 
+      function Declaration_Placement_Vertex
+        (Vertex    : Library_Graph_Vertex_Id;
+         Placement : Declaration_Placement_Kind)
+         return Library_Graph_Vertex_Id;
+      pragma Inline (Declaration_Placement_Vertex);
+      --  Obtain the spec or body of vertex Vertex depending on the requested
+      --  placement in Placement.
+
       ----------------------------
       -- Build_Invocation_Graph --
       ----------------------------
@@ -88,8 +96,9 @@ package body Bindo.Builders is
          --  Prepare the global data
 
          Inv_Graph :=
-           Create (Initial_Vertices => Number_Of_Elaborable_Units,
-                   Initial_Edges    => Number_Of_Elaborable_Units);
+           Create
+             (Initial_Vertices => Number_Of_Elaborable_Units,
+              Initial_Edges    => Number_Of_Elaborable_Units);
          Lib_Graph := Lib_G;
 
          For_Each_Elaborable_Unit (Create_Vertices'Access);
@@ -107,33 +116,24 @@ package body Bindo.Builders is
          pragma Assert (Present (Lib_Graph));
          pragma Assert (Present (IR_Id));
 
-         IR_Rec : Invocation_Relation_Record renames
-                    Invocation_Relations.Table (IR_Id);
-
-         pragma Assert (Present (IR_Rec.Invoker));
-         pragma Assert (Present (IR_Rec.Target));
+         Invoker_Sig : constant Invocation_Signature_Id := Invoker (IR_Id);
+         Target_Sig  : constant Invocation_Signature_Id := Target  (IR_Id);
 
-         Invoker : Invocation_Graph_Vertex_Id;
-         Target  : Invocation_Graph_Vertex_Id;
+         pragma Assert (Present (Invoker_Sig));
+         pragma Assert (Present (Target_Sig));
 
       begin
          --  Nothing to do when the target denotes an invocation construct that
          --  resides in a unit which will never be elaborated.
 
-         if not Needs_Elaboration (IR_Rec.Target) then
+         if not Needs_Elaboration (Target_Sig) then
             return;
          end if;
 
-         Invoker := Corresponding_Vertex (Inv_Graph, IR_Rec.Invoker);
-         Target  := Corresponding_Vertex (Inv_Graph, IR_Rec.Target);
-
-         pragma Assert (Present (Invoker));
-         pragma Assert (Present (Target));
-
          Add_Edge
            (G      => Inv_Graph,
-            Source => Invoker,
-            Target => Target,
+            Source => Corresponding_Vertex (Inv_Graph, Invoker_Sig),
+            Target => Corresponding_Vertex (Inv_Graph, Target_Sig),
             IR_Id  => IR_Id);
       end Create_Edge;
 
@@ -162,35 +162,25 @@ package body Bindo.Builders is
 
       procedure Create_Vertex
         (IC_Id  : Invocation_Construct_Id;
-         LGV_Id : Library_Graph_Vertex_Id)
+         Vertex : Library_Graph_Vertex_Id)
       is
+      begin
          pragma Assert (Present (Inv_Graph));
          pragma Assert (Present (Lib_Graph));
          pragma Assert (Present (IC_Id));
-         pragma Assert (Present (LGV_Id));
-
-         IC_Rec : Invocation_Construct_Record renames
-                    Invocation_Constructs.Table (IC_Id);
-
-         Body_LGV_Id : Library_Graph_Vertex_Id;
-
-      begin
-         --  Determine the proper library graph vertex which holds the body of
-         --  the invocation construct.
-
-         if IC_Rec.Placement = In_Body then
-            Body_LGV_Id := Proper_Body (Lib_Graph, LGV_Id);
-         else
-            pragma Assert (IC_Rec.Placement = In_Spec);
-            Body_LGV_Id := Proper_Spec (Lib_Graph, LGV_Id);
-         end if;
-
-         pragma Assert (Present (Body_LGV_Id));
+         pragma Assert (Present (Vertex));
 
          Add_Vertex
-           (G      => Inv_Graph,
-            IC_Id  => IC_Id,
-            LGV_Id => Body_LGV_Id);
+           (G           => Inv_Graph,
+            IC_Id       => IC_Id,
+            Body_Vertex =>
+              Declaration_Placement_Vertex
+                (Vertex    => Vertex,
+                 Placement => Body_Placement (IC_Id)),
+            Spec_Vertex =>
+              Declaration_Placement_Vertex
+                (Vertex    => Vertex,
+                 Placement => Spec_Placement (IC_Id)));
       end Create_Vertex;
 
       ---------------------
@@ -203,18 +193,37 @@ package body Bindo.Builders is
          pragma Assert (Present (U_Id));
 
          U_Rec  : Unit_Record renames ALI.Units.Table (U_Id);
-         LGV_Id : constant Library_Graph_Vertex_Id :=
+         Vertex : constant Library_Graph_Vertex_Id :=
                     Corresponding_Vertex (Lib_Graph, U_Id);
 
-         pragma Assert (Present (LGV_Id));
-
       begin
          for IC_Id in U_Rec.First_Invocation_Construct ..
                       U_Rec.Last_Invocation_Construct
          loop
-            Create_Vertex (IC_Id, LGV_Id);
+            Create_Vertex (IC_Id, Vertex);
          end loop;
       end Create_Vertices;
+
+      ----------------------------------
+      -- Declaration_Placement_Vertex --
+      ----------------------------------
+
+      function Declaration_Placement_Vertex
+        (Vertex    : Library_Graph_Vertex_Id;
+         Placement : Declaration_Placement_Kind)
+         return Library_Graph_Vertex_Id
+      is
+      begin
+         pragma Assert (Present (Lib_Graph));
+         pragma Assert (Present (Vertex));
+
+         if Placement = In_Body then
+            return Proper_Body (Lib_Graph, Vertex);
+         else
+            pragma Assert (Placement = In_Spec);
+            return Proper_Spec (Lib_Graph, Vertex);
+         end if;
+      end Declaration_Placement_Vertex;
    end Invocation_Graph_Builders;
 
    ----------------------------
@@ -235,7 +244,7 @@ package body Bindo.Builders is
       pragma Inline (Hash_Unit);
       --  Obtain the hash value of key U_Id
 
-      package UL is new Dynamic_Hash_Tables
+      package Unit_Line_Tables is new Dynamic_Hash_Tables
         (Key_Type              => Unit_Id,
          Value_Type            => Logical_Line_Number,
          No_Value              => No_Line_Number,
@@ -253,9 +262,10 @@ package body Bindo.Builders is
 
       Lib_Graph : Library_Graph := Library_Graphs.Nil;
 
-      Unit_To_Line : UL.Dynamic_Hash_Table := UL.Nil;
+      Unit_To_Line : Unit_Line_Tables.Dynamic_Hash_Table :=
+                       Unit_Line_Tables.Nil;
       --  The map of unit name -> line number, used to detect duplicate unit
-      --  names and report errors.
+      --  names in the forced-elaboration-order file and report errors.
 
       -----------------------
       -- Local subprograms --
@@ -348,20 +358,24 @@ package body Bindo.Builders is
       begin
          pragma Assert (Present (U_Id));
 
-         UL.Put (Unit_To_Line, U_Id, Line);
+         Unit_Line_Tables.Put (Unit_To_Line, U_Id, Line);
       end Add_Unit;
 
       -------------------------
       -- Build_Library_Graph --
       -------------------------
 
-      function Build_Library_Graph return Library_Graph is
+      function Build_Library_Graph
+        (Dynamically_Elaborated : Boolean) return Library_Graph
+      is
       begin
          --  Prepare the global data
 
          Lib_Graph :=
-           Create (Initial_Vertices => Number_Of_Elaborable_Units,
-                   Initial_Edges    => Number_Of_Elaborable_Units);
+           Create
+             (Initial_Vertices       => Number_Of_Elaborable_Units,
+              Initial_Edges          => Number_Of_Elaborable_Units,
+              Dynamically_Elaborated => Dynamically_Elaborated);
 
          For_Each_Elaborable_Unit (Create_Vertex'Access);
          For_Each_Elaborable_Unit (Create_Spec_And_Body_Edge'Access);
@@ -383,14 +397,11 @@ package body Bindo.Builders is
          pragma Assert (Present (Pred));
          pragma Assert (Present (Succ));
 
-         Pred_LGV_Id : constant Library_Graph_Vertex_Id :=
+         Pred_Vertex : constant Library_Graph_Vertex_Id :=
                          Corresponding_Vertex (Lib_Graph, Pred);
-         Succ_LGV_Id : constant Library_Graph_Vertex_Id :=
+         Succ_Vertex : constant Library_Graph_Vertex_Id :=
                          Corresponding_Vertex (Lib_Graph, Succ);
 
-         pragma Assert (Present (Pred_LGV_Id));
-         pragma Assert (Present (Succ_LGV_Id));
-
       begin
          Write_Unit_Name (Name (Pred));
          Write_Str (" <-- ");
@@ -399,8 +410,8 @@ package body Bindo.Builders is
 
          Add_Edge
            (G    => Lib_Graph,
-            Pred => Pred_LGV_Id,
-            Succ => Succ_LGV_Id,
+            Pred => Pred_Vertex,
+            Succ => Succ_Vertex,
             Kind => Forced_Edge);
       end Create_Forced_Edge;
 
@@ -409,15 +420,15 @@ package body Bindo.Builders is
       -------------------------
 
       procedure Create_Forced_Edges is
-         Curr_Unit : Unit_Id;
-         Iter      : Forced_Units_Iterator;
-         Prev_Unit : Unit_Id;
-         Unit_Line : Logical_Line_Number;
-         Unit_Name : Unit_Name_Type;
+         Current_Unit  : Unit_Id;
+         Iter          : Forced_Units_Iterator;
+         Previous_Unit : Unit_Id;
+         Unit_Line     : Logical_Line_Number;
+         Unit_Name     : Unit_Name_Type;
 
       begin
-         Prev_Unit    := No_Unit_Id;
-         Unit_To_Line := UL.Create (20);
+         Previous_Unit := No_Unit_Id;
+         Unit_To_Line  := Unit_Line_Tables.Create (20);
 
          --  Inspect the contents of the forced-elaboration-order file supplied
          --  to the binder using switch -f, and diagnose each unit accordingly.
@@ -425,36 +436,35 @@ package body Bindo.Builders is
          Iter := Iterate_Forced_Units;
          while Has_Next (Iter) loop
             Next (Iter, Unit_Name, Unit_Line);
-            pragma Assert (Present (Unit_Name));
 
-            Curr_Unit := Corresponding_Unit (Unit_Name);
+            Current_Unit := Corresponding_Unit (Unit_Name);
 
-            if not Present (Curr_Unit) then
+            if not Present (Current_Unit) then
                Missing_Unit_Info (Unit_Name);
 
-            elsif Is_Internal_Unit (Curr_Unit) then
+            elsif Is_Internal_Unit (Current_Unit) then
                Internal_Unit_Info (Unit_Name);
 
-            elsif Is_Duplicate_Unit (Curr_Unit) then
-               Duplicate_Unit_Error (Curr_Unit, Unit_Name, Unit_Line);
+            elsif Is_Duplicate_Unit (Current_Unit) then
+               Duplicate_Unit_Error (Current_Unit, Unit_Name, Unit_Line);
 
             --  Otherwise the unit is a valid candidate for a vertex. Create a
             --  forced edge between each pair of units.
 
             else
-               Add_Unit (Curr_Unit, Unit_Line);
+               Add_Unit (Current_Unit, Unit_Line);
 
-               if Present (Prev_Unit) then
+               if Present (Previous_Unit) then
                   Create_Forced_Edge
-                    (Pred => Prev_Unit,
-                     Succ => Curr_Unit);
+                    (Pred => Previous_Unit,
+                     Succ => Current_Unit);
                end if;
 
-               Prev_Unit := Curr_Unit;
+               Previous_Unit := Current_Unit;
             end if;
          end loop;
 
-         UL.Destroy (Unit_To_Line);
+         Unit_Line_Tables.Destroy (Unit_To_Line);
       end Create_Forced_Edges;
 
       -------------------------------
@@ -462,42 +472,37 @@ package body Bindo.Builders is
       -------------------------------
 
       procedure Create_Spec_And_Body_Edge (U_Id : Unit_Id) is
-         Aux_LGV_Id : Library_Graph_Vertex_Id;
-         LGV_Id     : Library_Graph_Vertex_Id;
+         Extra_Vertex : Library_Graph_Vertex_Id;
+         Vertex       : Library_Graph_Vertex_Id;
 
       begin
          pragma Assert (Present (Lib_Graph));
          pragma Assert (Present (U_Id));
 
-         LGV_Id := Corresponding_Vertex (Lib_Graph, U_Id);
-         pragma Assert (Present (LGV_Id));
+         Vertex := Corresponding_Vertex (Lib_Graph, U_Id);
 
          --  The unit denotes a body that completes a previous spec. Link the
          --  spec and body. Add an edge between the predecessor spec and the
          --  successor body.
 
-         if Is_Body_With_Spec (Lib_Graph, LGV_Id) then
-            Aux_LGV_Id :=
+         if Is_Body_With_Spec (Lib_Graph, Vertex) then
+            Extra_Vertex :=
               Corresponding_Vertex (Lib_Graph, Corresponding_Spec (U_Id));
-            pragma Assert (Present (Aux_LGV_Id));
-
-            Set_Corresponding_Item (Lib_Graph, LGV_Id, Aux_LGV_Id);
+            Set_Corresponding_Item (Lib_Graph, Vertex, Extra_Vertex);
 
             Add_Edge
               (G    => Lib_Graph,
-               Pred => Aux_LGV_Id,
-               Succ => LGV_Id,
+               Pred => Extra_Vertex,
+               Succ => Vertex,
                Kind => Spec_Before_Body_Edge);
 
          --  The unit denotes a spec with a completing body. Link the spec and
          --  body.
 
-         elsif Is_Spec_With_Body (Lib_Graph, LGV_Id) then
-            Aux_LGV_Id :=
+         elsif Is_Spec_With_Body (Lib_Graph, Vertex) then
+            Extra_Vertex :=
               Corresponding_Vertex (Lib_Graph, Corresponding_Body (U_Id));
-            pragma Assert (Present (Aux_LGV_Id));
-
-            Set_Corresponding_Item (Lib_Graph, LGV_Id, Aux_LGV_Id);
+            Set_Corresponding_Item (Lib_Graph, Vertex, Extra_Vertex);
          end if;
       end Create_Spec_And_Body_Edge;
 
@@ -531,11 +536,8 @@ package body Bindo.Builders is
          Withed_U_Id : constant Unit_Id :=
                          Corresponding_Unit (Withed_Rec.Uname);
 
-         pragma Assert (Present (Withed_U_Id));
-
-         Aux_LGV_Id    : Library_Graph_Vertex_Id;
          Kind          : Library_Graph_Edge_Kind;
-         Withed_LGV_Id : Library_Graph_Vertex_Id;
+         Withed_Vertex : Library_Graph_Vertex_Id;
 
       begin
          --  Nothing to do when the withed unit does not need to be elaborated.
@@ -545,8 +547,7 @@ package body Bindo.Builders is
             return;
          end if;
 
-         Withed_LGV_Id := Corresponding_Vertex (Lib_Graph, Withed_U_Id);
-         pragma Assert (Present (Withed_LGV_Id));
+         Withed_Vertex := Corresponding_Vertex (Lib_Graph, Withed_U_Id);
 
          --  The with comes with pragma Elaborate
 
@@ -557,15 +558,12 @@ package body Bindo.Builders is
             --  between the body of the withed predecessor and the withing
             --  successor.
 
-            if Is_Spec_With_Body (Lib_Graph, Withed_LGV_Id) then
-               Aux_LGV_Id :=
-                 Corresponding_Vertex
-                   (Lib_Graph, Corresponding_Body (Withed_U_Id));
-               pragma Assert (Present (Aux_LGV_Id));
-
+            if Is_Spec_With_Body (Lib_Graph, Withed_Vertex) then
                Add_Edge
                  (G    => Lib_Graph,
-                  Pred => Aux_LGV_Id,
+                  Pred =>
+                    Corresponding_Vertex
+                      (Lib_Graph, Corresponding_Body (Withed_U_Id)),
                   Succ => Succ,
                   Kind => Kind);
             end if;
@@ -586,7 +584,7 @@ package body Bindo.Builders is
 
          Add_Edge
            (G    => Lib_Graph,
-            Pred => Withed_LGV_Id,
+            Pred => Withed_Vertex,
             Succ => Succ,
             Kind => Kind);
       end Create_With_Edge;
@@ -596,18 +594,13 @@ package body Bindo.Builders is
       -----------------------
 
       procedure Create_With_Edges (U_Id : Unit_Id) is
-         LGV_Id : Library_Graph_Vertex_Id;
-
       begin
          pragma Assert (Present (Lib_Graph));
          pragma Assert (Present (U_Id));
 
-         LGV_Id := Corresponding_Vertex (Lib_Graph, U_Id);
-         pragma Assert (Present (LGV_Id));
-
          Create_With_Edges
            (U_Id => U_Id,
-            Succ => LGV_Id);
+            Succ => Corresponding_Vertex (Lib_Graph, U_Id));
       end Create_With_Edges;
 
       -----------------------
@@ -655,7 +648,7 @@ package body Bindo.Builders is
          pragma Assert (Present (Nam));
 
          Prev_Line : constant Logical_Line_Number :=
-                       UL.Get (Unit_To_Line, U_Id);
+                       Unit_Line_Tables.Get (Unit_To_Line, U_Id);
 
       begin
          Error_Msg_Nat_1  := Nat (Line);
@@ -698,7 +691,7 @@ package body Bindo.Builders is
       begin
          pragma Assert (Present (U_Id));
 
-         return UL.Contains (Unit_To_Line, U_Id);
+         return Unit_Line_Tables.Contains (Unit_To_Line, U_Id);
       end Is_Duplicate_Unit;
 
       -------------------------