Gate PRs on the Quiet bugprone Checks Only

Keep the six checks that report almost nothing on correct code and clear their remaining hits: drop redundant branch conditions, forward a forwarding reference, mark deliberate discards with (void), and explain the pointer-ordered sets whose order does not matter. Allow (void) to mark a discarded result.

.clang-tidy

@@ -1,5 +1,5 @@
 # clang-tidy configuration, enforced by the clang-tidy CI job on the lines a pull
-# request changes (scripts/clang_tidy_diff.py). Two things are reported.
+# request changes (scripts/clang_tidy_diff.py). Three things are reported.
 # Missing includes: a file should include the header for every symbol it uses, not
 # rely on the precompiled header or another header's includes. Run with --fix to
 # add them.
@@ -7,11 +7,29 @@
 # they reach every file that includes the header, and a using-declaration also
 # makes the header look like the one to include for that name. Qualify the name
 # in the header, and put the using in the source files that want it.
+# Likely bugs: an RAII object or a return value thrown away, an integer stored
+# as a character in a string, std::move on a forwarding reference, iteration
+# whose order depends on pointer values, and a condition already known true.
 # Every check listed here gates pull requests, so enable a new one only once the
 # code it flags on touched lines is reasonable to fix in passing.
-Checks: '-*,misc-include-cleaner,google-global-names-in-headers'
+Checks: >-
+  -*,
+  misc-include-cleaner,
+  google-global-names-in-headers,
+  bugprone-move-forwarding-reference,
+  bugprone-nondeterministic-pointer-iteration-order,
+  bugprone-redundant-branch-condition,
+  bugprone-string-integer-assignment,
+  bugprone-unused-raii,
+  bugprone-unused-return-value
 WarningsAsErrors: '*'
 CheckOptions:
+  # (void) marks a result dropped on purpose, such as a deliberate leak through
+  # unique_ptr::release().
+  bugprone-unused-return-value.AllowCastToVoid: true
+  # The default list without boost::system::error_code: Boost.Asio's overloads
+  # that take an error_code& also return it, and callers check the argument.
+  bugprone-unused-return-value.CheckedReturnTypes: '^::std::error_code$;^::std::error_condition$;^::std::errc$;^::std::expected$'
   # Missing includes only. Builds without the precompiled header break on these.
   misc-include-cleaner.UnusedIncludes: false
   # Headers that declare a symbol but are not the one to include: per-platform

src/libslic3r/GCode.cpp

@@ -6865,8 +6865,7 @@ LayerResult GCode::process_layer(
                     }
                 #endif
 
-                    if (support_dontcare)
-                        support_extruder = dontcare_extruder;
+                    support_extruder = dontcare_extruder;
                 }
                 else if (support_dontcare || interface_dontcare) {
                     // Some support will be printed with "don't care" material, preferably non-soluble.

src/libslic3r/Polyline.hpp

@@ -248,7 +248,7 @@ inline void polylines_merge(PointsType &dst, bool dst_first, PointsType &&src, b
     } else if (! src_first)
         std::reverse(src.begin(), src.end());
     // Merge src into dst.
-    append(dst, std::move(src));
+    append(dst, std::forward<PointsType>(src));
 }
 
 const Point& leftmost_point(const Polylines &polylines);

src/libslic3r/PresetBundle.cpp

@@ -3386,6 +3386,7 @@ void PresetBundle::load_installed_filaments(AppConfig &config)
                 //      compatible_filaments.insert(&filament);
             }
         // and mark these filaments as installed, therefore this code will not be executed at the next start of the application.
+        // NOLINTNEXTLINE(bugprone-nondeterministic-pointer-iteration-order) - each is set by name, so only the log order varies
         for (const auto &filament: compatible_filaments) {
             BOOST_LOG_TRIVIAL(info) << __FUNCTION__ << boost::format(": set filament %1% to visible by default")%filament->name;
             config.set(AppConfig::SECTION_FILAMENTS, filament->name, "true");
@@ -3412,6 +3413,7 @@ void PresetBundle::load_installed_sla_materials(AppConfig &config)
 						comp_sla_materials.insert(&material);
 			}
 		// and mark these SLA materials as installed, therefore this code will not be executed at the next start of the application.
+		// NOLINTNEXTLINE(bugprone-nondeterministic-pointer-iteration-order) - each is set by name, so the order does not matter
 		for (const auto &material: comp_sla_materials)
             config.set(AppConfig::SECTION_MATERIALS, material->name, "true");
     }

src/slic3r/GUI/GUI_App.cpp

@@ -3953,9 +3953,7 @@ bool GUI_App::on_init_network(bool try_backup)
                 if (!bambu_source) {
                     BOOST_LOG_TRIVIAL(info) << __FUNCTION__ << ": can not get bambu source module!";
                     m_networking_compatible = false;
-                    if (should_load_networking_plugin) {
-                        m_networking_need_update = true;
-                    }
+                    m_networking_need_update = true;
                 }
             } else {
                 if (try_backup) {
@@ -3966,9 +3964,7 @@ bool GUI_App::on_init_network(bool try_backup)
                     goto __retry;
                 }
                 BOOST_LOG_TRIVIAL(info) << __FUNCTION__ << ": on_init_network, version dismatch, need upload network module";
-                if (should_load_networking_plugin) {
-                    m_networking_need_update = true;
-                }
+                m_networking_need_update = true;
             }
         } else {
             BOOST_LOG_TRIVIAL(info) << __FUNCTION__ << ": on_init_network, load dll failed";
@@ -3986,10 +3982,8 @@ bool GUI_App::on_init_network(bool try_backup)
                 load_agent_dll = Slic3r::NetworkAgent::initialize_network_module(false, config_version);
                 goto __retry;
             }
-            if (should_load_networking_plugin) {
-                BOOST_LOG_TRIVIAL(info) << __FUNCTION__ << ": on_init_network, need upload network module";
-                m_networking_need_update = true;
-            }
+            BOOST_LOG_TRIVIAL(info) << __FUNCTION__ << ": on_init_network, need upload network module";
+            m_networking_need_update = true;
         }
     }
 
@@ -8293,7 +8287,7 @@ bool GUI_App::load_language(wxString language, bool initial)
 
     // Release the old locales, create new locales.
     //FIXME wxWidgets cause havoc if the current locale is deleted. We just forget it causing memory leaks for now.
-    m_wxLocale.release();
+    (void) m_wxLocale.release();
     m_wxLocale = Slic3r::make_unique<wxLocale>();
     m_wxLocale->Init(locale_language_info->Language);
     // Override language at the active wxTranslations class (which is stored in the active m_wxLocale)

tests/libslic3r/test_utils.cpp

@@ -165,10 +165,10 @@ TEST_CASE("write_file_atomically survives two threads writing one target", "[uti
 
     std::thread other([&] {
         for (int i = 0; i < 50; ++i)
-            write_file_atomically(target.string(), a);
+            (void) write_file_atomically(target.string(), a);
     });
     for (int i = 0; i < 50; ++i)
-        write_file_atomically(target.string(), b);
+        (void) write_file_atomically(target.string(), b);
     other.join();
 
     std::string content;