Clear source info diagnostics when the option changes

Improve existing test to cover this case.

For eng/ide/ada_language_server#1593

Author: AnthonyLeonardoGracio

source/ada/lsp-ada_documents-source_info_diagnostics.adb

@@ -32,6 +32,8 @@ package body LSP.Ada_Documents.Source_Info_Diagnostics is
 
       Current_Project_Stamp : constant LSP.Ada_Handlers.Project_Stamp :=
         Self.Handler.Get_Project_Stamp;
+      Is_Enabled : constant Boolean :=
+        Self.Handler.Source_Info_Diagnostics_Enabled;
    begin
       --  The project has been reloaded: compute source information diagnostics
       --  again since the set of source files might have been changed.
@@ -40,6 +42,14 @@ package body LSP.Ada_Documents.Source_Info_Diagnostics is
          return True;
       end if;
 
+      --  The 'sourceInfoDiagnostics' option has just changed: always return
+      --  True in this case (e.g: to clear any existing diagnostic when the
+      --  option gets disabled)
+      if Self.Enabled /= Is_Enabled then
+         Self.Enabled := Is_Enabled;
+         return True;
+      end if;
+
       return False;
    end Has_New_Diagnostic;
 
@@ -57,7 +67,7 @@ package body LSP.Ada_Documents.Source_Info_Diagnostics is
       --  If the unit associated to the document belongs to the fallback context
       --  it means that the document's file does not belong the loaded project:
       --  emit a hint diagnostic in that case.
-      if Context.Is_Fallback_Context then
+      if Self.Is_Enabled and then Context.Is_Fallback_Context then
          declare
             Diag_Msg : constant String :=
               (if Self.Handler.Get_Project_Status.Is_Project_Loaded

source/ada/lsp-ada_documents-source_info_diagnostics.ads

@@ -51,6 +51,10 @@ private
       --  Used to detect when the project has been reloaded.
       --  We want to update source information diagnostics only after
       --  project reloade.
+
+      Enabled : Boolean := True;
+      --  Used to keep track of the 'sourceInfoDiagnostics' option, which
+      --  enables/disables source information diagnostics.
    end record;
 
 end LSP.Ada_Documents.Source_Info_Diagnostics;

testsuite/ada_lsp/diagnostics.source_information/test.json

@@ -112,6 +112,31 @@
          ]
       }
    },
+   {
+      "send": {
+         "request": {
+            "jsonrpc": "2.0",
+            "method": "workspace/didChangeConfiguration",
+            "params": {
+               "settings": {
+                  "ada": {
+                     "projectFile": "$URI{default.gpr}",
+                     "sourceInfoDiagnostics": false
+                  }
+               }
+            }
+         },
+         "wait": [
+            {
+               "method": "textDocument/publishDiagnostics",
+               "params": {
+                  "uri": "$URI{main.adb}",
+                  "diagnostics": []
+               }
+            }
+         ]
+      }
+   },
    {
       "stop": {
          "exit_code": 0