U429-030: Fix signatureHelp active parameter + Prefix notation

Handle prefix notation: differentiate between a paremeter prefix
and a package prefix.
Properly select the active parameter + handle designators.

Add a test.

Author: AdrienBoulanger

source/ada/lsp-ada_handlers.adb

@@ -2794,6 +2794,7 @@ package body LSP.Ada_Handlers is
       return LSP.Messages.Server_Responses.SignatureHelp_Response
    is
       use Libadalang.Analysis;
+      use Langkit_Support.Slocs;
       use LSP.Messages;
 
       Value   : LSP.Messages.SignatureHelpParams renames
@@ -2858,7 +2859,15 @@ package body LSP.Ada_Handlers is
       Response.result := (others => <>);
 
       --  Check if we are inside a function call and get the caller name
-      Get_Call_Expr_Name (Node, Active_Position, Designator, Name_Node);
+      Get_Call_Expr_Name
+        (Node            => Node,
+         Cursor_Line     =>
+           Langkit_Support.Slocs.Line_Number (Value.position.line + 1),
+         Cursor_Column   =>
+           Langkit_Support.Slocs.Column_Number (Value.position.character) + 1,
+         Active_Position => Active_Position,
+         Designator      => Designator,
+         Name_Node       => Name_Node);
 
       if Name_Node = Libadalang.Analysis.No_Name then
          return Response;

source/ada/lsp-lal_utils.adb

@@ -35,7 +35,7 @@ with Langkit_Support.Token_Data_Handlers;
 
 with Pp.Actions;
 
-with LSP.Types; use LSP.Types;
+with LSP.Types;             use LSP.Types;
 
 package body LSP.Lal_Utils is
 
@@ -356,13 +356,36 @@ package body LSP.Lal_Utils is
 
    procedure Get_Call_Expr_Name
      (Node            : Libadalang.Analysis.Ada_Node'Class;
+      Cursor_Line     : Langkit_Support.Slocs.Line_Number;
+      Cursor_Column   : Langkit_Support.Slocs.Column_Number;
       Active_Position : out LSP.Types.LSP_Number;
       Designator      : out Libadalang.Analysis.Ada_Node;
       Name_Node       : out Libadalang.Analysis.Name)
    is
+      use Langkit_Support.Slocs;
       Cur_Node : Ada_Node := Node.As_Ada_Node;
+
+      function Is_Active (N : Ada_Node) return Boolean;
+      --  Check if N contains the cursor
+
+      ---------------
+      -- Is_Active --
+      ---------------
+
+      function Is_Active (N : Ada_Node) return Boolean
+      is
+         S : constant Langkit_Support.Slocs.Source_Location_Range :=
+           N.Sloc_Range;
+      begin
+         return S.Start_Line <= Cursor_Line
+           and then Cursor_Line <= S.End_Line
+           and then S.Start_Column <= Cursor_Column
+           and then Cursor_Column <= S.End_Column;
+      end Is_Active;
+
    begin
       Active_Position := 0;
+      Designator := Libadalang.Analysis.No_Ada_Node;
       Name_Node := Libadalang.Analysis.No_Name;
 
       if not Cur_Node.Is_Null
@@ -404,11 +427,21 @@ package body LSP.Lal_Utils is
            Cur_Node.As_Call_Expr;
          Suffix_Node     : constant Libadalang.Analysis.Ada_Node'Class :=
            Call_Expr_Node.F_Suffix;
-         Node_Parents    : constant Libadalang.Analysis.Ada_Node_Array :=
-           Node.Parents;
       begin
          Name_Node := Call_Expr_Node.F_Name;
 
+         if Name_Node.Kind in Ada_Dotted_Name_Range then
+            declare
+               Dot_Name : constant Dotted_Name := Name_Node.As_Dotted_Name;
+            begin
+               --  If the prefix is a parameter then increase the
+               --  Active_Position by 1
+               if Dot_Name.P_Is_Dot_Call (Imprecise_Fallback => True) then
+                  Active_Position := Active_Position + 1;
+               end if;
+            end;
+         end if;
+
          if Suffix_Node = Libadalang.Analysis.No_Ada_Node then
             return;
          end if;
@@ -417,10 +450,8 @@ package body LSP.Lal_Utils is
          if Suffix_Node.Kind in Ada_Assoc_List_Range then
             for Assoc of Suffix_Node.As_Assoc_List loop
                Designator := Assoc.As_Param_Assoc.F_Designator;
-               for Parent of Node_Parents loop
-                  exit when Assoc = Parent;
-               end loop;
                Active_Position := Active_Position + 1;
+               exit when Is_Active (Assoc.As_Ada_Node);
             end loop;
          end if;
          --  The active position index starts at 0

source/ada/lsp-lal_utils.ads

@@ -135,13 +135,17 @@ package LSP.Lal_Utils is
 
    procedure Get_Call_Expr_Name
      (Node            : Libadalang.Analysis.Ada_Node'Class;
+      Cursor_Line     : Langkit_Support.Slocs.Line_Number;
+      Cursor_Column   : Langkit_Support.Slocs.Column_Number;
       Active_Position : out LSP.Types.LSP_Number;
       Designator      : out Libadalang.Analysis.Ada_Node;
       Name_Node       : out Libadalang.Analysis.Name);
    --  If Node is inside a Call_Expr returns the following:
    --  Active_Position: the index of the parameter in the Call_Expr
    --  Designator: the designator of the Active_Position
    --  Name_Node: the name of the Call_Expr
+   --  Cursor_Line and Cursor_Column the position of the cursor when the
+   --  request was triggered.
 
    procedure Get_Parameters
      (Node : Libadalang.Analysis.Basic_Decl;

testsuite/ada_lsp/U429-030.signatureHelp.dot_call/bar.adb

@@ -0,0 +1,22 @@
+package body Bar is
+
+   -----------
+   -- Hello --
+   -----------
+
+   procedure Hello (A : Integer; B : Float) is
+   begin
+      null;
+   end Hello;
+
+   -----------
+   -- Hello --
+   -----------
+
+   procedure Hello (M : access My_Type; A : Integer; B : Float) is
+   begin
+      null;
+   end Hello;
+
+end Bar;
+

testsuite/ada_lsp/U429-030.signatureHelp.dot_call/bar.ads

@@ -0,0 +1,13 @@
+package Bar is
+
+   procedure Hello (A : Integer; B : Float);
+
+   type My_Type is tagged
+      record
+         B : Boolean;
+      end record;
+   type My_Access is access all My_Type;
+
+   procedure Hello (M : access My_Type; A : Integer; B : Float);
+
+end Bar;

testsuite/ada_lsp/U429-030.signatureHelp.dot_call/default.gpr

@@ -0,0 +1,3 @@
+project Default is
+   for Main use ("foo.adb");
+end Default;

testsuite/ada_lsp/U429-030.signatureHelp.dot_call/foo.adb

@@ -0,0 +1,12 @@
+with Bar; use Bar;
+
+procedure Foo is
+   M : My_Access := null;
+begin
+   --  Hello (null, 2, 3);
+
+   --  Bar.Hello (A => 1, M => null, 3);
+
+   --  M.Hello (B => 3, A => 2);
+
+end Foo;