Factor stringifying canonicalize_path error handling

Author: strager

src/file-canonical.cpp

@@ -710,32 +710,10 @@ sloppy_result<canonical_path_result> canonicalize_path_sloppy(
         if (!canonical) return canonical.error();
         return sloppy_result<canonical_path_result>(*canonical);
       },
-      [&](boost::leaf::e_errno error,
-          const e_canonicalizing_path &canonicalizing) {
-        return sloppy_result<canonical_path_result>::failure(
-            "failed to canonicalize "s + canonicalizing.path + ": "s + path +
-            ": "s + std::strerror(error.value));
-      },
-      [&](boost::leaf::e_errno error) {
-        return sloppy_result<canonical_path_result>::failure(
-            "failed to canonicalize "s + path + ": "s +
-            std::strerror(error.value));
-      },
-      [&](e_too_many_symlinks) {
+      make_canonicalize_path_error_handlers([](std::string &&message) {
         return sloppy_result<canonical_path_result>::failure(
-            "failed to canonicalize "s + path +
-            ": Too many levels of symlink"s);
-      },
-      [&](e_invalid_argument_empty_path) {
-        return sloppy_result<canonical_path_result>::failure(
-            "failed to canonicalize empty path: "s + std::strerror(EINVAL));
-      },
-      [&]() {
-        QLJS_ASSERT(false);  // One of the above handlers should have handled
-                             // the error already.
-        return sloppy_result<canonical_path_result>::failure(
-            "failed to canonicalize path: "s + path);
-      });
+            std::move(message));
+      }));
 }
 
 sloppy_result<canonical_path_result> canonicalize_path_sloppy(

src/quick-lint-js/file-canonical.h

@@ -4,13 +4,15 @@
 #ifndef QUICK_LINT_JS_FILE_CANONICAL_H
 #define QUICK_LINT_JS_FILE_CANONICAL_H
 
+#include <boost/leaf/common.hpp>
 #include <boost/leaf/result.hpp>
 #include <cstddef>
 #include <functional>
 #include <optional>
 #include <quick-lint-js/sloppy-result.h>
 #include <string>
 #include <string_view>
+#include <tuple>
 
 namespace quick_lint_js {
 class canonical_path_result;
@@ -125,6 +127,41 @@ boost::leaf::result<canonical_path_result> canonicalize_path_2(
 sloppy_result<canonical_path_result> canonicalize_path_sloppy(const char *path);
 sloppy_result<canonical_path_result> canonicalize_path_sloppy(
     const std::string &path);
+
+// Valid signatures for handle_error:
+// <<any rvalue result type>> handle_error(const std::string &message);
+// <<any rvalue result type>> handle_error(std::string &&message);
+template <class Func>
+auto make_canonicalize_path_error_handlers(const Func &handle_error) {
+  using namespace std::literals::string_literals;
+  return std::tuple(
+      [handle_error](const boost::leaf::e_file_name &path,
+                     boost::leaf::e_errno error,
+                     const e_canonicalizing_path &canonicalizing) {
+        return handle_error("failed to canonicalize "s + canonicalizing.path +
+                            ": "s + path.value + ": "s +
+                            std::strerror(error.value));
+      },
+      [handle_error](const boost::leaf::e_file_name &path,
+                     boost::leaf::e_errno error) {
+        return handle_error("failed to canonicalize "s + path.value + ": "s +
+                            std::strerror(error.value));
+      },
+      [handle_error](const boost::leaf::e_file_name &path,
+                     e_too_many_symlinks) {
+        return handle_error("failed to canonicalize "s + path.value +
+                            ": Too many levels of symlink"s);
+      },
+      [handle_error](e_invalid_argument_empty_path) {
+        return handle_error("failed to canonicalize empty path: "s +
+                            std::strerror(EINVAL));
+      },
+      [handle_error]() {
+        QLJS_ASSERT(false);  // One of the above handlers should have handled
+                             // the error already.
+        return handle_error("failed to canonicalize path"s);
+      });
+}
 }
 
 namespace std {

test/test-file-canonical.cpp

@@ -83,15 +83,9 @@ boost::leaf::result<void> canonicalize_expecting_failure(const Path& path) {
 }
 
 auto fail_test_error_handlers() {
-  return std::tuple(
-      [](boost::leaf::e_errno error) {
-        ADD_FAILURE() << "error: " << std::strerror(error.value);
-      },
-      [](e_too_many_symlinks) { ADD_FAILURE() << "error: too many symlinks"; },
-      [](e_invalid_argument_empty_path) {
-        ADD_FAILURE() << "error: invalid argument: empty path";
-      },
-      []() { ADD_FAILURE() << "unknown error"; });
+  return make_canonicalize_path_error_handlers([](const std::string& message) {
+    ADD_FAILURE() << "error: " << message;
+  });
 }
 
 bool process_ignores_filesystem_permissions() noexcept {