Libadalang.Project_Provider: add a trace for unit resolution

Also create a dedicated one for project partition.

extensions/src/libadalang-project_provider.adb

@@ -302,8 +302,8 @@ package body Libadalang.Project_Provider is
                and then Unit_Files.Reference (Prj_Pos).Element.all
                         /= Part.Unit_Files.Reference (Part_Pos).Element.all
             then
-               if Trace.Is_Active then
-                  Trace.Trace
+               if Partition_Trace.Is_Active then
+                  Partition_Trace.Trace
                     ("Found conflicting source files for unit "
                      & To_String (Unit_Name) & " in " & Name (Project)
                      & " and " & Part_Image (Part));
@@ -390,7 +390,8 @@ package body Libadalang.Project_Provider is
    is
       Partition : Aggregate_Part_Vectors.Vector;
    begin
-      Trace.Increase_Indent ("Trying to partition " & Name (Root (Tree)));
+      Partition_Trace.Increase_Indent
+        ("Trying to partition " & Name (Root (Tree)));
 
       if Is_Aggregate_Project (Root (Tree)) then
 
@@ -488,22 +489,23 @@ package body Libadalang.Project_Provider is
          end;
       end if;
 
-      Trace.Decrease_Indent;
+      Partition_Trace.Decrease_Indent;
 
       --  For debuggability, log how the Tree was partitioned
 
-      if Trace.Is_Active then
-         Trace.Increase_Indent ("Input project partitioned into:");
+      if Partition_Trace.Is_Active then
+         Partition_Trace.Increase_Indent ("Input project partitioned into:");
          for Cur in Partition.Iterate loop
             declare
                N    : constant Positive :=
                   Aggregate_Part_Vectors.To_Index (Cur);
                Part : Aggregate_Part renames Partition.Element (N).all;
             begin
-               Trace.Trace ("Part" & N'Image & ": " & Part_Image (Part));
+               Partition_Trace.Trace
+                 ("Part" & N'Image & ": " & Part_Image (Part));
             end;
          end loop;
-         Trace.Decrease_Indent;
+         Partition_Trace.Decrease_Indent;
       end if;
 
       --  For GPR2, make sure that all projects are namespace roots
@@ -693,6 +695,27 @@ package body Libadalang.Project_Provider is
       Filename       : in out US.Unbounded_String;
       PLE_Root_Index : in out Natural)
    is
+      function Request_Image return String
+      is (Kind'Image & " of unit " & Image (Name, With_Quotes => True));
+
+      procedure Trace_Found;
+      --  Assuming that we found the requested unit, log information about it
+      --  to the project provider trace.
+
+      -----------------
+      -- Trace_Found --
+      -----------------
+
+      procedure Trace_Found is
+      begin
+         if Resolution_Trace.Is_Active then
+            Resolution_Trace.Trace
+              (Request_Image & " is located in "
+               & US.To_String (Filename)
+               & " at" & PLE_Root_Index'Image);
+         end if;
+      end Trace_Found;
+
       Str_Name  : constant String :=
         Libadalang.Unit_Files.Unit_String_Name (Name);
    begin
@@ -732,6 +755,7 @@ package body Libadalang.Project_Provider is
                         if Fullname'Length /= 0 then
                            GNAT.Task_Lock.Unlock;
                            Filename := US.To_Unbounded_String (Fullname);
+                           Trace_Found;
                            return;
                         end if;
                      end;
@@ -770,6 +794,7 @@ package body Libadalang.Project_Provider is
                     US.To_Unbounded_String (String (Unit.Source.Value));
                   PLE_Root_Index :=
                     (if Unit.Index = 0 then 1 else Positive (Unit.Index));
+                  Trace_Found;
                   return;
                end if;
             end;
@@ -779,6 +804,9 @@ package body Libadalang.Project_Provider is
       --  If we reach this point, we have not found a unit handled by this
       --  provider that matches the requested name/kind.
 
+      if Resolution_Trace.Is_Active then
+         Resolution_Trace.Trace ("No unit found for " & Request_Image);
+      end if;
       Filename := US.Null_Unbounded_String;
       PLE_Root_Index := 1;
    end Get_Unit_Location;

extensions/src/libadalang-project_provider.ads

@@ -27,8 +27,15 @@ package Libadalang.Project_Provider is
    package LAL renames Libadalang.Analysis;
    package Prj renames GNATCOLL.Projects;
 
-   Trace : constant GNATCOLL.Traces.Trace_Handle := GNATCOLL.Traces.Create
-     ("LIBADALANG.PROJECT_PROVIDER", GNATCOLL.Traces.From_Config);
+   Trace : constant GNATCOLL.Traces.Trace_Handle :=
+     GNATCOLL.Traces.Create
+       ("LIBADALANG.PROJECT_PROVIDER", GNATCOLL.Traces.From_Config);
+   Partition_Trace : constant GNATCOLL.Traces.Trace_Handle :=
+     GNATCOLL.Traces.Create
+       ("LIBADALANG.PROJECT_PROVIDER.PARTITION", GNATCOLL.Traces.From_Config);
+   Resolution_Trace : constant GNATCOLL.Traces.Trace_Handle :=
+     GNATCOLL.Traces.Create
+       ("LIBADALANG.PROJECT_PROVIDER.RESOLUTION", GNATCOLL.Traces.From_Config);
 
    Unsupported_View_Error : exception;
    --  See the ``Create_Project_Unit_Provider`` functions below

testsuite/tests/ada_api/gpr2_project_partition/basic/main.adb

@@ -23,7 +23,7 @@ procedure Main is
    PAPs    : GPR2_Provider_And_Projects_Array_Access;
 
 begin
-   GNATCOLL.Traces.Parse_Config ("LIBADALANG.PROJECT_PROVIDER=yes");
+   GNATCOLL.Traces.Parse_Config ("LIBADALANG.PROJECT_PROVIDER.PARTITION=yes");
    Put_Line ("Loading the project:");
    Options.Add_Switch (GPR2.Options.P, "ap1.gpr");
    if not Tree.Load (Options, With_Runtime => True)

testsuite/tests/ada_api/gpr2_project_partition/basic/test.out

@@ -1,9 +1,9 @@
 Loading the project:
-[LIBADALANG.PROJECT_PROVIDER] Trying to partition AP1
-   [LIBADALANG.PROJECT_PROVIDER] Found conflicting source files for unit P1 in P3 and <P1, P2>
-[LIBADALANG.PROJECT_PROVIDER] Input project partitioned into:
-   [LIBADALANG.PROJECT_PROVIDER] Part 1: <P1, P2>
-   [LIBADALANG.PROJECT_PROVIDER] Part 2: <P3>
+[LIBADALANG.PROJECT_PROVIDER.PARTITION] Trying to partition AP1
+   [LIBADALANG.PROJECT_PROVIDER.PARTITION] Found conflicting source files for unit P1 in P3 and <P1, P2>
+[LIBADALANG.PROJECT_PROVIDER.PARTITION] Input project partitioned into:
+   [LIBADALANG.PROJECT_PROVIDER.PARTITION] Part 1: <P1, P2>
+   [LIBADALANG.PROJECT_PROVIDER.PARTITION] Part 2: <P3>
   * P1 P2
   * P3
 

testsuite/tests/ada_api/project_partition/basic/main.adb

@@ -23,7 +23,7 @@ procedure Main is
    PAPs : Provider_And_Projects_Array_Access;
 
 begin
-   GNATCOLL.Traces.Parse_Config ("LIBADALANG.PROJECT_PROVIDER=yes");
+   GNATCOLL.Traces.Parse_Config ("LIBADALANG.PROJECT_PROVIDER.PARTITION=yes");
    Put_Line ("Loading the project:");
    Initialize (Env);
    Load (Tree.all, Create (+"ap1.gpr"), Env);

testsuite/tests/ada_api/project_partition/basic/test.out

@@ -1,9 +1,9 @@
 Loading the project:
-[LIBADALANG.PROJECT_PROVIDER] Trying to partition AP1
-   [LIBADALANG.PROJECT_PROVIDER] Found conflicting source files for unit p1 in P3 and <P1, P2>
-[LIBADALANG.PROJECT_PROVIDER] Input project partitioned into:
-   [LIBADALANG.PROJECT_PROVIDER] Part 1: <P1, P2>
-   [LIBADALANG.PROJECT_PROVIDER] Part 2: <P3>
+[LIBADALANG.PROJECT_PROVIDER.PARTITION] Trying to partition AP1
+   [LIBADALANG.PROJECT_PROVIDER.PARTITION] Found conflicting source files for unit p1 in P3 and <P1, P2>
+[LIBADALANG.PROJECT_PROVIDER.PARTITION] Input project partitioned into:
+   [LIBADALANG.PROJECT_PROVIDER.PARTITION] Part 1: <P1, P2>
+   [LIBADALANG.PROJECT_PROVIDER.PARTITION] Part 2: <P3>
   * P1 P2
   * P3