Compiler_Module_Name_Diagnostics.H

/*
                          Aleph_w

  Data structures & Algorithms
  version 2.0.0b
  https://github.com/lrleon/Aleph-w

  This file is part of Aleph-w library

  Copyright (c) 2002-2026 Leandro Rabindranath Leon

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*/

/** @file Compiler_Module_Name_Diagnostics.H
 *  @brief Reusable diagnostics for top-level inter-module name resolution.
 *
 *  This header translates one `Compiler_Module_Name_Resolution` into a
 *  structured diagnostic with stable wording, notes, and help messages. It is
 *  intended for frontends that reuse the module-surface resolver but still want
 *  frontend-specific error codes and subject names such as "callee" or
 *  "imported type".
 *
 *  @ingroup Utilities
 */

#ifndef COMPILER_MODULE_NAME_DIAGNOSTICS_H
#define COMPILER_MODULE_NAME_DIAGNOSTICS_H

#include <string>

#include <Compiler_Module_Name_Resolver.H>
#include <ah-diagnostics.H>

namespace Aleph {
/** @brief Emits one structured diagnostic for a module-name resolution failure.
 *
 *  When `resolution.ok()` is true, this helper emits nothing and returns `0`.
 *
 *  @param diagnostics Diagnostic engine receiving the error.
 *  @param span Source span of the failed use site.
 *  @param resolution Structured module-name resolution result.
 *  @param code Stable frontend-specific diagnostic code.
 *  @param subject User-facing noun phrase such as `"line-frontend callee"`.
 *  @return Diagnostic index, or `0` if no diagnostic was emitted.
 */
inline size_t compiler_emit_module_name_resolution_diagnostic(
  Diagnostic_Engine &diagnostics,
  const Source_Span &span,
  const Compiler_Module_Name_Resolution &resolution,
  const std::string &code,
  const std::string &subject)
{
  if (resolution.ok())
    return 0;

  switch (resolution.status)
    {
    case Compiler_Module_Name_Resolution_Status::Resolved:
      return 0;

    case Compiler_Module_Name_Resolution_Status::Missing_Module:
      return diagnostics
        .error(span,
               "cannot resolve " + subject + " '" + resolution.symbol_name + "' because module '"
                 + resolution.module_name + "' is not available")
        .code(code)
        .note("the current binding view does not contain that module")
        .help("ensure the source was loaded and its imports were resolved before semantic checks")
        .emit();

    case Compiler_Module_Name_Resolution_Status::Missing_Name:
      return diagnostics.error(span, "unknown " + subject + " '" + resolution.symbol_name + "'")
        .code(code)
        .note("module '" + resolution.module_name
              + "' does not expose that name through local declarations or direct imports")
        .help("declare the symbol locally or import a module that exports it")
        .emit();

    case Compiler_Module_Name_Resolution_Status::Wrong_Kind:
      return diagnostics.error(span, "invalid " + subject + " '" + resolution.symbol_name + "'")
        .code(code)
        .note("module '" + resolution.module_name + "' resolves that name as "
              + compiler_module_export_kind_name(resolution.binding.kind))
        .help("use a symbol exported with the expected kind")
        .emit();

    case Compiler_Module_Name_Resolution_Status::Ambiguous_Name:
      return diagnostics.error(span, "ambiguous " + subject + " '" + resolution.symbol_name + "'")
        .code(code)
        .note("module '" + resolution.module_name
              + "' sees multiple matching providers for that name")
        .help("rename one provider or reduce the set of direct imports")
        .emit();
    }

  return 0;
}
}  // namespace Aleph

#endif