Существует ли библиотека Delphi, которая возвращает все эффективные исходные пути для проекта?

Вы можете использовать OpenTools API, чтобы получить путь поиска активного проекта (объединенный из активной конфигурации и набора параметров) и путь к глобальной библиотеке IDE. Вот блок из моего пакета быстрого тестирования:

unit Unit1;

interface

uses
  Windows, SysUtils, Classes,
  ToolsAPI;

type
  TTestWizard = class(TNotifierObject, IOTAWizard, IOTAMenuWizard)
  private
    { IOTAWizard }
    function GetIDString: string;
    function GetName: string;
    function GetState: TWizardState;
    procedure Execute;
    { IOTAMenuWizard }
    function GetMenuText: string;
  private
    function AddLibraryPaths(Strings: TStrings): Integer;
    function AddProjectSearchPaths(Strings: TStrings): Integer;
  end;

procedure Register;

implementation

uses
  Dialogs,
  DCCStrs, TypInfo;

var
  WizardIndex: Integer = -1;

procedure GetEnvironmentVariables(Strings: TStrings);
var
  P: PChar;
begin
  P := nil;
  Strings.BeginUpdate;
  try
    Strings.Clear;
    P := GetEnvironmentStrings;
    repeat
      Strings.Add(P);
      P := StrEnd(P);
      Inc(P);
    until P^ = #0;
  finally
    if Assigned(P) then
      FreeEnvironmentStrings(P);
    Strings.EndUpdate;
  end;
end;

function EvaluateEnvironmentVariables(const S: string): string;
var
  Strings: TStringList;
  I: Integer;
begin
  Result := S;

  Strings := TStringList.Create;
  try
    GetEnvironmentVariables(Strings);
    for I := 0 to Strings.Count - 1 do
      Result := StringReplace(Result, Format('$(%s)', [Strings.Names[I]]), Strings.ValueFromIndex[I],
        [rfReplaceAll, rfIgnoreCase]);
  finally
    Strings.Free;
  end;
end;

procedure Register;
begin
  WizardIndex := (BorlandIDEServices as IOTAWizardServices).AddWizard(TTestWizard.Create);
end;

{ TTestWizard private: IOTAWizard }

function TTestWizard.GetIDString: string;
begin
  Result := 'TOndrej.TestWizard';
end;

function TTestWizard.GetName: string;
begin
  Result := 'TestWizard';
end;

function TTestWizard.GetState: TWizardState;
begin
  Result := [wsEnabled];
end;

procedure TTestWizard.Execute;
var
  Paths: TStrings;
begin
  Paths := TStringList.Create;
  try
    AddProjectSearchPaths(Paths);
    AddLibraryPaths(Paths);
    ShowMessage(EvaluateEnvironmentVariables(Paths.Text));
  finally
    Paths.Free;
  end;
end;

{ TTestWizard private: IOTAMenuWizard }

function TTestWizard.GetMenuText: string;
begin
  Result := GetIDString;
end;

function TTestWizard.AddLibraryPaths(Strings: TStrings): Integer;
var
  Paths: TStringList;
  EnvironmentOptions: IOTAEnvironmentOptions;
begin
  Paths := TStringList.Create;
  try
    Paths.Delimiter := ';';
    Paths.StrictDelimiter := True;
    EnvironmentOptions := (BorlandIDEServices as IOTAServices).GetEnvironmentOptions;
    Paths.DelimitedText := EnvironmentOptions.Values['LibraryPath'];
    Strings.AddStrings(Paths);
    Result := Paths.Count;
  finally
    Paths.Free;
  end;
end;

function TTestWizard.AddProjectSearchPaths(Strings: TStrings): Integer;
var
  ActiveProject: IOTAProject;
  Configurations: IOTAProjectOptionsConfigurations;
  Configuration: IOTABuildConfiguration;
  Paths: TStringList;
begin
  Result := -1;
  ActiveProject := GetActiveProject;
  if not Assigned(ActiveProject) then
    Exit;
  Configurations := ActiveProject.ProjectOptions as IOTAProjectOptionsConfigurations;
  Configuration := Configurations.ActiveConfiguration;
  if not Assigned(Configuration) then
    Exit;

  Paths := TStringList.Create;
  try
    Configuration.GetValues(sUnitSearchPath, Paths, True);
    Strings.AddStrings(Paths);
    Result := Paths.Count;
  finally
    Paths.Free;
  end;
end;

initialization

finalization
  if WizardIndex <> -1 then
    (BorlandIDEServices as IOTAWizardServices).RemoveWizard(WizardIndex);

end.