Avoid center plug for internal solid infill (spiral inset) (#15705)

avoid center plug for internal solid infill

scripts/clang_tidy_diff.py

@@ -8,6 +8,9 @@ include) fails wherever the error is. Headers are compiled on their own, and
 fail only on errors in their changed lines. Deleting an #include also fails
 on every use, changed or not, that now lacks the header it provided.
 
+With -- --fix, clang-tidy adds the missing includes, on those lines only, and
+each file it changed is checked again so that only what remains is reported.
+
 The checks come from .clang-tidy at the repository root. The compile database
 must come from a configure with SLIC3R_PCH=OFF, or the precompiled header hides
 missing includes.
@@ -102,9 +105,10 @@ def is_checked(path):
 
 def changed_files(merge_base):
     # Against the working tree, so a local run covers uncommitted edits too.
-    # core.quotePath=false keeps a non-ASCII path unquoted, so parse_diff sees its b/ prefix.
+    # core.quotePath=false keeps a non-ASCII path unquoted, and the explicit prefixes
+    # override diff.noprefix and diff.mnemonicPrefix, so parse_diff sees its b/ prefix.
     diff = subprocess.run(["git", "-c", "core.quotePath=false", "diff", "-U0", "--no-color", "--no-ext-diff",
-                           "--diff-filter=AMR", merge_base],
+                           "--src-prefix=a/", "--dst-prefix=b/", "--diff-filter=AMR", merge_base],
                           check=True, capture_output=True, **UTF8).stdout
     return {path: change for path, change in parse_diff(diff).items() if is_checked(path)}
 
@@ -201,13 +205,19 @@ def errors_alone_at(revision, clang_tidy, build_dir, path):
 
 
 def check_file(clang_tidy, build_dir, merge_base, path, change, extra_args):
-    """Run clang-tidy on one file and return (failed, output, failing diagnostics)."""
+    """Run clang-tidy on one file and return (failed, output, failing diagnostics, fixed)."""
+    fixing = any(arg.startswith("--fix") for arg in extra_args)
+    if fixing:
+        with open(path, "rb") as f:
+            before = f.read()
     # A deleted include can orphan uses on unchanged lines, so such a file is
-    # checked whole and the findings narrowed here. --fix keeps the line filter
-    # so it never rewrites unrelated code.
-    whole = bool(change.removed_includes) and not extra_args
+    # checked whole and the findings narrowed here. --fix keeps a line filter so
+    # it never rewrites unrelated code, which for such a file means a second,
+    # fixing run limited to the lines the first one found wanting.
+    whole = bool(change.removed_includes)
     returncode, output, diagnostics = run_clang_tidy(clang_tidy, build_dir, path,
-                                                     None if whole else change.lines, extra_args)
+                                                     None if whole else change.lines,
+                                                     [] if whole else extra_args)
     real = os.path.realpath(path)
 
     def introduced(d):
@@ -223,14 +233,25 @@ def check_file(clang_tidy, build_dir, merge_base, path, change, extra_args):
         if errors and change.removed_includes:
             with open(path, encoding="utf-8") as f:
                 text = f.read()
-            before = errors_alone_at(merge_base, clang_tidy, build_dir, path)
+            before_sites = errors_alone_at(merge_base, clang_tidy, build_dir, path)
             failing += [d for d in errors if d not in failing
-                        and (error_sites([d], text) - before)]
-        return bool(failing), output, failing
-    if whole:
+                        and (error_sites([d], text) - before_sites)]
+        failed = bool(failing)
+    elif whole:
         failing = [d for d in diagnostics if d.is_compile_error or introduced(d)]
-        return bool(failing), output, failing
-    return returncode != 0, output, diagnostics
+        failed = bool(failing)
+    else:
+        failing, failed = diagnostics, returncode != 0
+    if not fixing:
+        return failed, output, failing, False
+    if whole and failing:
+        lines = change.lines + [[d.line, d.line] for d in failing if os.path.realpath(d.file) == real]
+        run_clang_tidy(clang_tidy, build_dir, path, lines, extra_args)
+    with open(path, "rb") as f:
+        if f.read() == before:
+            return failed, output, failing, False
+    # Checked again, so what is reported is what the fixes left.
+    return check_file(clang_tidy, build_dir, merge_base, path, change, [])[:3] + (True,)
 
 
 def main():
@@ -263,11 +284,14 @@ def main():
     annotate = os.environ.get("GITHUB_ACTIONS") == "true"
     root = os.getcwd() + os.sep
     failed = []
+    fixed = []
     with ThreadPoolExecutor(max_workers=args.jobs) as pool:
         jobs = {path: pool.submit(check_file, args.clang_tidy, args.build_dir, merge_base, path, change, args.extra_args)
                 for path, change in todo}
         for path, job in jobs.items():
-            file_failed, output, diagnostics = job.result()
+            file_failed, output, diagnostics, file_fixed = job.result()
+            if file_fixed:
+                fixed.append(path)
             if not file_failed:
                 continue
             failed.append(path)
@@ -282,6 +306,13 @@ def main():
             if len(diagnostics) > MAX_REPORTED:
                 print(f"... and {len(diagnostics) - MAX_REPORTED} more")
 
+    if fixed:
+        print(f"\nAdded includes to {len(fixed)} file(s):")
+        for path in fixed:
+            print(f"    {path}")
+    if failed and fixed:
+        print(f"\nclang-tidy still fails on {len(failed)} file(s); the findings above are what --fix could not add.")
+        return 1
     if failed:
         print(f"\nclang-tidy failed on {len(failed)} file(s). Add the includes it names, or apply its "
               "suggestions locally with scripts/run_clang_tidy.sh --fix (scripts\\run_clang_tidy.ps1 -Fix on Windows).")

scripts/disable_validation.entitlements

@@ -4,10 +4,5 @@
 <dict>
     <key>com.apple.security.cs.disable-library-validation</key>
     <true/>
-    <!-- The Bambu network plug-in's code protector rewrites one of its own signed code pages
-         after loading. Under the hardened runtime macOS kills the process when that page is
-         paged back in; this lets it run, as Bambu Studio's signature does. -->
-    <key>com.apple.security.cs.allow-unsigned-executable-memory</key>
-    <true/>
 </dict>
 </plist>

scripts/run_clang_tidy.sh

@@ -6,8 +6,9 @@
 #   scripts/run_clang_tidy.sh --fix      also add the missing includes it names
 #
 # It configures a separate build directory (build-tidy) without the precompiled
-# header, installs the pinned clang-tidy into a virtual environment inside it, and
-# runs scripts/clang_tidy_diff.py the way CI does. Uncommitted changes are checked too.
+# header, uses the clang-tidy on your system or installs the pinned one into a
+# virtual environment inside it, and runs scripts/clang_tidy_diff.py the way CI
+# does. Uncommitted changes are checked too.
 
 set -euo pipefail
 
@@ -23,7 +24,8 @@ Usage: scripts/run_clang_tidy.sh [options]
                        deps/build/<arch> on macOS)
   -j, --jobs N         parallel clang-tidy runs (default: all cores)
       --fix            apply clang-tidy's fixes (adds the missing includes)
-  -y, --yes            install missing tools without asking
+  -y, --yes            install missing tools without asking; another clang-tidy
+                       version found on the system is then not offered
   -h, --help           show this help
 EOF
 }
@@ -136,12 +138,38 @@ REQUIREMENTS="$ROOT/scripts/clang_tidy_requirements.txt"
 PINNED=$(sed -n 's/^clang-tidy==//p' "$REQUIREMENTS")
 VENV="$BUILD_DIR/clang-tidy-venv"
 
-if [ -n "${CLANG_TIDY:-}" ]; then
+is_pinned() {
+    [ -x "$1" ] && "$1" --version 2>/dev/null | grep -q "version $PINNED"
+}
+
+CLANG_TIDY="${CLANG_TIDY:-}"
+if [ -n "$CLANG_TIDY" ]; then
     # Set by the caller: use it as is.
-    :
+    is_pinned "$CLANG_TIDY" || echo "Warning: $CLANG_TIDY is not clang-tidy $PINNED, so results may differ from CI." >&2
 else
+    # One already on the system comes first: the pinned version outright, another
+    # version if the user accepts the difference. The pinned version is installed
+    # into a virtual environment otherwise.
+    INSTALLED=""
+    for candidate in $(command -v clang-tidy "clang-tidy-${PINNED%%.*}" || true) \
+                     "/usr/lib/llvm-${PINNED%%.*}/bin/clang-tidy" \
+                     "$(brew --prefix llvm 2>/dev/null || true)/bin/clang-tidy"; do
+        if is_pinned "$candidate"; then
+            CLANG_TIDY="$candidate"
+            break
+        fi
+        [ -z "$INSTALLED" ] && [ -x "$candidate" ] && INSTALLED="$candidate"
+    done
+    if [ -z "$CLANG_TIDY" ] && [ -n "$INSTALLED" ] && [ "$YES" = 0 ] && ! is_pinned "$VENV/bin/clang-tidy"; then
+        echo "Found $INSTALLED, which is $("$INSTALLED" --version | sed -n 's/.*version \([0-9.]*\).*/\1/p' | head -n 1), not the $PINNED CI uses, so results may differ slightly."
+        if ask "Use it anyway?"; then
+            CLANG_TIDY="$INSTALLED"
+        fi
+    fi
+fi
+if [ -z "$CLANG_TIDY" ]; then
     CLANG_TIDY="$VENV/bin/clang-tidy"
-    if [ ! -x "$CLANG_TIDY" ] || ! "$CLANG_TIDY" --version | grep -q "version $PINNED"; then
+    if ! is_pinned "$CLANG_TIDY"; then
         if ask "clang-tidy $PINNED (the version CI uses) is not installed. Install it into $VENV?"; then
             mkdir -p "$BUILD_DIR"
             if ! python3 -m venv "$VENV"; then
@@ -158,9 +186,6 @@ else
         fi
     fi
 fi
-if ! "$CLANG_TIDY" --version | grep -q "version $PINNED"; then
-    echo "Warning: $CLANG_TIDY is not clang-tidy $PINNED, so results may differ from CI." >&2
-fi
 
 # --- Dependencies -------------------------------------------------------------
 
@@ -217,7 +242,12 @@ cmake --build "$BUILD_DIR" --target git_commit_hash_header >/dev/null
 
 if [ -z "$BASE" ]; then
     REMOTE=$(git remote -v | awk '/github\.com[:\/]OrcaSlicer\/OrcaSlicer(\.git)? \(fetch\)/ { print $1; exit }')
-    REMOTE="${REMOTE:-origin}"
+    if [ -z "$REMOTE" ]; then
+        # Against a fork's main that already has the commits, nothing is checked.
+        echo "Warning: no remote points at github.com/OrcaSlicer/OrcaSlicer, so this compares against origin/main." >&2
+        echo "If origin is your fork, add the upstream remote (git remote add upstream https://github.com/OrcaSlicer/OrcaSlicer.git) or pass --base." >&2
+        REMOTE=origin
+    fi
     if [ "$FETCH" = 1 ]; then
         git fetch --quiet "$REMOTE" main
     fi

scripts/tests/test_clang_tidy_diff.py

@@ -155,6 +155,8 @@ class TestSubprocessCalls(unittest.TestCase):
         diff = "+++ b/src/libslic3r/Über.cpp\n@@ -1,0 +2 @@\n+// 打印\n"
         files, call, _ = self.run_patched(clang_tidy_diff.changed_files, "base", stdout=diff)
         self.assertIn("core.quotePath=false", call.args[0])
+        # Whatever diff.noprefix or diff.mnemonicPrefix a user has set.
+        self.assertIn("--dst-prefix=b/", call.args[0])
         self.assertEqual(call.kwargs["encoding"], "utf-8")
         self.assertEqual(files["src/libslic3r/Über.cpp"].lines, [[2, 2]])
 
@@ -167,5 +169,60 @@ class TestSubprocessCalls(unittest.TestCase):
         self.assertEqual(call.kwargs["encoding"], "utf-8")
 
 
+class TestCheckFileFix(unittest.TestCase):
+    """check_file with -- --fix: what clang-tidy is run on, and what is reported afterwards."""
+
+    def setUp(self):
+        self.dir = tempfile.TemporaryDirectory()
+        self.addCleanup(self.dir.cleanup)
+        self.path = os.path.join(self.dir.name, "Color.cpp")
+        with open(self.path, "w") as f:
+            f.write("int x;\n")
+
+    def finding(self, line, include=""):
+        return clang_tidy_diff.Diagnostic(self.path, line, 1, "error",
+                                          'no header providing "x" is directly included [misc-include-cleaner]', include)
+
+    def check(self, change, results, fix_writes=None):
+        """Run check_file with run_clang_tidy answering from `results` in turn; the --fix run
+        rewrites the file with `fix_writes` when given. Returns (result, calls)."""
+        calls = []
+
+        def run(clang_tidy, build_dir, path, lines, extra_args):
+            calls.append((lines, extra_args))
+            if "--fix" in extra_args and fix_writes is not None:
+                with open(path, "w") as f:
+                    f.write(fix_writes)
+            return results[len(calls) - 1]
+
+        with mock.patch.object(clang_tidy_diff, "run_clang_tidy", side_effect=run):
+            result = clang_tidy_diff.check_file("clang-tidy", "build", "base", self.path, change, ["--fix"])
+        return result, calls
+
+    def test_a_deleted_include_is_fixed_on_the_lines_it_orphaned_only(self):
+        change = clang_tidy_diff.FileChange(lines=[[4, 4]], removed_includes={"libslic3r/Point.hpp"})
+        orphaned = self.finding(50, "<libslic3r/Point.hpp>")
+        unrelated = self.finding(60, "<vector>")
+        (failed, _, failing, fixed), calls = self.check(
+            change, [(1, "", [orphaned, unrelated]), (1, "", [orphaned]), (0, "", [])], fix_writes="#include <libslic3r/Point.hpp>\n")
+        self.assertEqual(calls, [(None, []), ([[4, 4], [50, 50]], ["--fix"]), (None, [])])
+        self.assertEqual((failed, failing, fixed), (False, [], True))
+
+    def test_a_file_the_fix_did_not_change_keeps_its_findings(self):
+        change = clang_tidy_diff.FileChange(lines=[[4, 4]])
+        error = clang_tidy_diff.Diagnostic(self.path, 4, 1, "error", "unknown type name 'Foo' [clang-diagnostic-error]")
+        (failed, _, failing, fixed), calls = self.check(change, [(1, "", [error])])
+        self.assertEqual(calls, [([[4, 4]], ["--fix"])])
+        self.assertEqual((failed, failing, fixed), (True, [error], False))
+
+    def test_a_changed_file_is_checked_again_and_reports_what_is_left(self):
+        change = clang_tidy_diff.FileChange(lines=[[4, 4]])
+        error = clang_tidy_diff.Diagnostic(self.path, 4, 1, "error", "unknown type name 'Foo' [clang-diagnostic-error]")
+        (failed, _, failing, fixed), calls = self.check(
+            change, [(1, "", [self.finding(4, "<vector>"), error]), (1, "", [error])], fix_writes="#include <vector>\n")
+        self.assertEqual(calls, [([[4, 4]], ["--fix"]), ([[4, 4]], [])])
+        self.assertEqual((failed, failing, fixed), (True, [error], True))
+
+
 if __name__ == "__main__":
     unittest.main()

src/dev-utils/platform/osx/entitlements.plist

@@ -5,10 +5,5 @@
   <!-- for dynamic loading of libraries without signature validation. Used for 3dconnection drivers.-->
   <key>com.apple.security.cs.disable-library-validation</key>  
   <true/>
-  <!-- The Bambu network plug-in's code protector rewrites one of its own signed code pages
-       after loading. Under the hardened runtime macOS kills the process when that page is
-       paged back in; this lets it run, as Bambu Studio's signature does. -->
-  <key>com.apple.security.cs.allow-unsigned-executable-memory</key>
-  <true/>
 </dict>
 </plist>

src/libslic3r/Fill/FillSpiralInset.cpp

@@ -352,6 +352,16 @@ void FillSpiralInset::_fill_surface_single(const FillParams& params,
     assert(params.use_arachne);
     assert(this->print_config != nullptr && this->print_object_config != nullptr);
 
+    // Internal solid infill must not add Arachne's standalone thin walls: one of those walls can
+    // become the extra centre point after the spiral has finished. Top and bottom surfaces keep
+    // Arachne, including the centre plug handled by generate_spiral_insets().
+    if (params.extrusion_role == erSolidInfill) {
+        Polylines polylines;
+        this->_fill_surface_single(params, thickness_layers, direction, expolygon, polylines);
+        append(thick_polylines_out, to_thick_polylines(std::move(polylines), scaled<coord_t>(this->spacing)));
+        return;
+    }
+
     // Only a solid surface is worth the variable width walls; a sparse one falls back to plain loops.
     if (params.density <= 0.9999f || params.dont_adjust) {
         Polylines polylines;

src/libslic3r/GCode/GCodeProcessor.cpp

@@ -751,6 +751,50 @@ template<typename T>
     }
 }
 
+namespace {
+// Writes G-code to a file in blocks and records in lines_ends the file offset after every '\n'
+class GCodeFileWriter
+{
+public:
+    GCodeFileWriter(FilePtr& out, const std::string& out_path, std::vector<size_t>& lines_ends, const char* error_message)
+        : m_out(out), m_out_path(out_path), m_lines_ends(lines_ends), m_error_message(error_message)
+    {}
+    ~GCodeFileWriter() { assert(m_buffer.empty() || std::uncaught_exceptions() > 0); }
+
+    void append(std::string_view text)
+    {
+        const size_t text_pos = m_file_pos + m_buffer.size();
+        for (size_t i = text.find('\n'); i != std::string_view::npos; i = text.find('\n', i + 1))
+            m_lines_ends.emplace_back(text_pos + i + 1);
+        m_buffer += text;
+        if (m_buffer.size() >= GCodeProcessor::Output_Block_Size)
+            flush();
+    }
+
+    void flush()
+    {
+        if (m_buffer.empty())
+            return;
+        fwrite(m_buffer.data(), 1, m_buffer.size(), m_out.f);
+        if (ferror(m_out.f)) {
+            m_out.close();
+            boost::nowide::remove(m_out_path.c_str());
+            throw Slic3r::RuntimeError(m_error_message);
+        }
+        m_file_pos += m_buffer.size();
+        m_buffer.clear();
+    }
+
+private:
+    FilePtr&             m_out;
+    const std::string&   m_out_path;
+    std::vector<size_t>& m_lines_ends;
+    const char*          m_error_message;
+    std::string          m_buffer;
+    size_t               m_file_pos{0};
+};
+} // namespace
+
 // Helper class to modify and export gcode to file
 class ExportLines
 {
@@ -765,16 +809,6 @@ public:
     enum class EWriteType { BySize, ByTime };
 
 private:
-    static void update_lines_ends_and_out_file_pos(const std::string& out_string, std::vector<size_t>& lines_ends, size_t* out_file_pos)
-    {
-        for (size_t i = 0; i < out_string.size(); ++i) {
-            if (out_string[i] == '\n')
-                lines_ends.emplace_back((out_file_pos != nullptr) ? *out_file_pos + i + 1 : i + 1);
-        }
-        if (out_file_pos != nullptr)
-            *out_file_pos += out_string.size();
-    }
-
     struct LineData
     {
         std::string                                                                        line;
@@ -814,12 +848,14 @@ private:
     EWriteType m_write_type{EWriteType::BySize};
     // Time machines containing g1 times cache
     const std::array<GCodeProcessor::TimeMachine, static_cast<size_t>(PrintEstimatedStatistics::ETimeMode::Count)>& m_machines;
+    // Output file writer
+    GCodeFileWriter& m_writer;
     // Current time
     std::array<float, static_cast<size_t>(PrintEstimatedStatistics::ETimeMode::Count)> m_times{0.0f, 0.0f};
-    // Current size in bytes
+    // Current size of the cache in bytes
     size_t m_size{0};
 
-    // gcode lines cache
+    // gcode lines cache, used only when writing by time
     std::deque<LineData> m_lines;
     size_t               m_added_lines_counter{0};
     // map of gcode line ids from original to final
@@ -827,16 +863,16 @@ private:
     std::vector<std::pair<size_t, size_t>> m_gcode_lines_map;
 
     size_t m_times_cache_id{0};
-    size_t m_out_file_pos{0};
 
 public:
-    ExportLines(EWriteType type, const std::array<GCodeProcessor::TimeMachine, static_cast<size_t>(PrintEstimatedStatistics::ETimeMode::Count)>& machines)
+    ExportLines(EWriteType type, const std::array<GCodeProcessor::TimeMachine, static_cast<size_t>(PrintEstimatedStatistics::ETimeMode::Count)>& machines, GCodeFileWriter& writer)
 #ifndef NDEBUG
         : m_statistics(*this)
         , m_write_type(type)
-        , m_machines(machines){}
+        , m_machines(machines)
+        , m_writer(writer){}
 #else
-        : m_write_type(type), m_machines(machines)
+        : m_write_type(type), m_machines(machines), m_writer(writer)
     {}
 #endif // NDEBUG
 
@@ -890,11 +926,14 @@ public:
         if (line.empty())
             return;
 
-        m_lines.push_back({line, m_times});
+        if (m_write_type == EWriteType::ByTime) {
+            m_lines.push_back({line, m_times});
 #ifndef NDEBUG
-        m_statistics.add_line(line.length());
+            m_statistics.add_line(line.length());
 #endif // NDEBUG
-        m_size += line.length();
+            m_size += line.length();
+        } else
+            m_writer.append(line);
         ++m_added_lines_counter;
         if (!ignore_from_move) {
             assert(!m_gcode_lines_map.empty());
@@ -960,65 +999,35 @@ public:
         }
     }
 
-    // write to file:
-    // m_write_type == EWriteType::ByTime - all lines older than m_time - backtrace_time
-    // m_write_type == EWriteType::BySize - all lines if current size is greater than 65535 bytes
-    void write(FilePtr& out, float backtrace_time, GCodeProcessorResult& result, const std::string& out_path)
+    // when writing by time, pass the cached lines older than m_times[Normal] - backtrace_time to the writer
+    void write(float backtrace_time)
     {
-        if (m_lines.empty())
+        if (m_write_type != EWriteType::ByTime)
             return;
 
-        // collect lines to write into a single string
-        std::string out_string;
-        if (!m_lines.empty()) {
-            if (m_write_type == EWriteType::ByTime) {
-                while (m_lines.front().times[Normal] < m_times[Normal] - backtrace_time) {
-                    const LineData& data = m_lines.front();
-                    out_string += data.line;
-                    m_size -= data.line.length();
-                    m_lines.pop_front();
+        while (!m_lines.empty() && m_lines.front().times[Normal] < m_times[Normal] - backtrace_time) {
+            const LineData& data = m_lines.front();
+            m_writer.append(data.line);
+            m_size -= data.line.length();
+            m_lines.pop_front();
 #ifndef NDEBUG
-                    m_statistics.remove_line();
+            m_statistics.remove_line();
 #endif // NDEBUG
-                }
-            } else {
-                if (m_size > 65535) {
-                    while (!m_lines.empty()) {
-                        out_string += m_lines.front().line;
-                        m_lines.pop_front();
-                    }
-                    m_size = 0;
-#ifndef NDEBUG
-                    m_statistics.remove_all_lines();
-#endif // NDEBUG
-                }
-            }
-        }
-
-        {
-            write_to_file(out, out_string, result, out_path);
-            update_lines_ends_and_out_file_pos(out_string, result.lines_ends, &m_out_file_pos);
         }
     }
 
-    // flush the current content of the cache to file
-    void flush(FilePtr& out, GCodeProcessorResult& result, const std::string& out_path)
+    // flush the current content of the cache and the writer to file
+    void flush()
     {
-        // collect lines to flush into a single string
-        std::string out_string;
         while (!m_lines.empty()) {
-            out_string += m_lines.front().line;
+            m_writer.append(m_lines.front().line);
             m_lines.pop_front();
         }
         m_size = 0;
 #ifndef NDEBUG
         m_statistics.remove_all_lines();
 #endif // NDEBUG
-
-        {
-            write_to_file(out, out_string, result, out_path);
-            update_lines_ends_and_out_file_pos(out_string, result.lines_ends, &m_out_file_pos);
-        }
+        m_writer.flush();
     }
 
     void synchronize_moves(GCodeProcessorResult& result) const
@@ -1051,20 +1060,7 @@ public:
 
     size_t get_size() const { return m_size; }
 
-private:
-    void write_to_file(FilePtr& out, const std::string& out_string, GCodeProcessorResult& result, const std::string& out_path)
-    {
-        if (!out_string.empty()) {
-            if (true) {
-                fwrite((const void*) out_string.c_str(), 1, out_string.length(), out.f);
-                if (ferror(out.f)) {
-                    out.close();
-                    boost::nowide::remove(out_path.c_str());
-                    throw Slic3r::RuntimeError("GCode processor post process export failed.\nIs the disk full?");
-                }
-            }
-        }
-    }
+    void reserve(size_t lines_count) { m_gcode_lines_map.reserve(lines_count); }
 };
 
 void GCodeProcessor::run_post_process()
@@ -1160,8 +1156,13 @@ void GCodeProcessor::run_post_process()
         last_exported_stop[i] = time_in_minutes(m_time_processor.machines[i].time);
     }
 
+    m_result.lines_ends.clear();
+    // m_result.lines_ends.emplace_back(std::vector<size_t>());
+    GCodeFileWriter writer(out, out_path, m_result.lines_ends, "GCode processor post process export failed.\nIs the disk full?");
     ExportLines export_line(m_result.backtrace_enabled ? ExportLines::EWriteType::ByTime : ExportLines::EWriteType::BySize,
-        m_time_processor.machines);
+        m_time_processor.machines, writer);
+    // The line map holds an entry for each line of the file, and the first pass counted them
+    export_line.reserve(m_line_id);
 
     // replace placeholder lines with the proper final value
     // gcode_line is in/out parameter, to reduce expensive memory allocation
@@ -1535,9 +1536,6 @@ void GCodeProcessor::run_post_process()
         }
     };
 
-    m_result.lines_ends.clear();
-    // m_result.lines_ends.emplace_back(std::vector<size_t>());
-
     // Orca: freshly collect SKIPPABLE ranges each post-process pass. The ranges are stored on the
     // member (rather than a local) so the injection pass can consume them, hence the clear here to
     // avoid stale ranges on re-invocation.
@@ -1802,7 +1800,7 @@ void GCodeProcessor::run_post_process()
 
                     if (!gcode_line.empty())
                         export_line.append_line(gcode_line);
-                    export_line.write(out, 1.1f * max_backtrace_time, m_result, out_path);
+                    export_line.write(1.1f * max_backtrace_time);
                     gcode_line.clear();
                 }
             }
@@ -1844,7 +1842,7 @@ void GCodeProcessor::run_post_process()
         }
     }
 
-    export_line.flush(out, m_result, out_path);
+    export_line.flush();
 
     out.close();
     in.close();
@@ -1992,31 +1990,13 @@ void GCodeProcessor::run_second_pass_injection()
     // The rewrite may shift byte positions (once the injector inserts lines), so rebuild lines_ends from scratch.
     // With an empty map the scanned '\n' offsets reproduce the current lines_ends exactly.
     m_result.lines_ends.clear();
-    size_t out_file_pos = 0;
-
-    auto write_out = [&out, &out_path, this, &out_file_pos](std::string& str) {
-        if (str.empty())
-            return;
-        fwrite((const void*) str.c_str(), 1, str.length(), out.f);
-        if (ferror(out.f)) {
-            out.close();
-            boost::nowide::remove(out_path.c_str());
-            throw Slic3r::RuntimeError(std::string("GCode processor pre-heat injection pass failed.\nIs the disk full?\n"));
-        }
-        for (size_t i = 0; i < str.size(); ++i) {
-            if (str[i] == '\n')
-                m_result.lines_ends.emplace_back(out_file_pos + i + 1);
-        }
-        out_file_pos += str.size();
-        str.clear();
-    };
+    GCodeFileWriter writer(out, out_path, m_result.lines_ends, "GCode processor pre-heat injection pass failed.\nIs the disk full?\n");
 
     // Orca: read/split lines with EOL-preserving semantics (keep the original \r and \n bytes, and
     // synthesize no trailing newline). This is required for the empty-map identity: normalizing every
     // line ending to "\n" would not be byte-identical if the finished file used \r\n or lacked a
     // final newline.
     std::string gcode_line;
-    std::string export_buffer;
     unsigned int line_id = 0;
     auto op_it = inserted_operation_lines.begin();
     std::vector<char> buffer(65536 * 10, 0);
@@ -2058,16 +2038,14 @@ void GCodeProcessor::run_second_pass_injection()
                     }
                     ++op_it;
                 }
-                export_buffer += gcode_line;
+                writer.append(gcode_line);
                 gcode_line.clear();
-                if (export_buffer.length() >= 65536)
-                    write_out(export_buffer);
             }
         }
         if (eof)
             break;
     }
-    write_out(export_buffer);
+    writer.flush();
 
     out.close();
     in.close();

src/libslic3r/GCode/GCodeProcessor.hpp

@@ -491,6 +491,9 @@ class Print;
         static const std::string VFlush_End_Tag;
         static const std::string External_Purge_Tag;
     public:
+        // Size of the blocks the post-processing passes write the G-code in
+        static constexpr size_t Output_Block_Size = 65536;
+
         // Orca: SKIPPABLE region tags, stored as static strings (the FLUSH idiom above) rather than
         // a CustomETags/CustomTags array. Public so the emission sites (WipeTower / change_filament
         // path) can reference them single-sourced.

src/libslic3r/PerimeterGenerator.cpp

@@ -759,6 +759,59 @@ static void clip_inner_walls_over_top(std::vector<Arachne::VariableWidthLines> &
     }
 }
 
+// ORCA: only_one_wall_top - widest bead of the given walls.
+static coord_t widest_bead(const std::vector<Arachne::VariableWidthLines> &walls)
+{
+    coord_t widest = 0;
+    for (const Arachne::VariableWidthLines &group : walls)
+        for (const Arachne::ExtrusionLine &el : group)
+            for (const Arachne::ExtrusionJunction &j : el.junctions)
+                widest = std::max(widest, j.w);
+    return widest;
+}
+
+// ORCA: only_one_wall_top - length of the walls running further than tolerance from the reference walls, outside the
+// excluded area.
+static double length_off_reference(const std::vector<Arachne::VariableWidthLines> &walls, const Arachne::VariableWidthLines &reference,
+                                   const ExPolygons &excluded, coord_t tolerance)
+{
+    auto append_centerlines = [](const Arachne::VariableWidthLines &lines, Polylines &out) {
+        for (const Arachne::ExtrusionLine &el : lines) {
+            if (el.junctions.size() < 2)
+                continue;
+            Polyline &centerline = out.emplace_back();
+            centerline.points.reserve(el.junctions.size());
+            for (const Arachne::ExtrusionJunction &j : el.junctions)
+                centerline.points.emplace_back(j.p);
+        }
+    };
+    Polylines wall_centerlines;
+    Polylines reference_centerlines;
+    for (const Arachne::VariableWidthLines &group : walls)
+        append_centerlines(group, wall_centerlines);
+    append_centerlines(reference, reference_centerlines);
+
+    Polylines off_reference = diff_pl(wall_centerlines, offset(reference_centerlines, float(tolerance)));
+    if (! excluded.empty())
+        off_reference = diff_pl(off_reference, excluded);
+    return total_length(off_reference);
+}
+
+// ORCA: only_one_wall_top - area covered by the given walls at their local widths.
+static Polygons walls_footprint(const Arachne::VariableWidthLines &walls)
+{
+    Polygons footprint;
+    for (const Arachne::ExtrusionLine &el : walls)
+        for (size_t i = 1; i < el.junctions.size(); ++ i) {
+            const Arachne::ExtrusionJunction &a     = el.junctions[i - 1];
+            const Arachne::ExtrusionJunction &b     = el.junctions[i];
+            const coord_t                     width = std::max(a.w, b.w);
+            if (width > 0)
+                append(footprint, offset(Polyline(a.p, b.p), float(width) / 2.f));
+        }
+    return union_(footprint);
+}
+
 void PerimeterGenerator::split_top_surfaces(const ExPolygons &orig_polygons, ExPolygons &top_fills,
                                             ExPolygons &non_top_polygons, ExPolygons &fill_clip) const {
     // other perimeters
@@ -2546,44 +2599,90 @@ void PerimeterGenerator::process_arachne()
         if (inner_loop_number >= 0) {
             assert(upper_slices != nullptr);
 
-            // Infill contour bounding box.
-            BoundingBox infill_contour_bbox = get_extents(infill_contour);
-            infill_contour_bbox.offset(SCALED_EPSILON);
-            
             coord_t perimeter_width = this->perimeter_flow.scaled_width();
 
-            // Get top ExPolygons from current infill contour.
-            Polygons upper_slices_clipped;
-            if (object_config->interface_shells) {
-                auto upper_slicer_same_region = to_expolygons(this->upper_slices_same_region->surfaces);
-                upper_slices_clipped = ClipperUtils::clip_clipper_polygons_with_subject_bbox(upper_slicer_same_region, infill_contour_bbox);
-            } else
-                upper_slices_clipped = ClipperUtils::clip_clipper_polygons_with_subject_bbox(*upper_slices, infill_contour_bbox);
+            // Filter out areas that are too thin and expand top surface polygons a bit to hide the wall line.
+            // ORCA: skip if the top surface area is smaller than "min_width_top_surface"
+            const float top_surface_min_width = std::max<float>(float(ext_perimeter_spacing) / 4.f + scaled<float>(0.00001), float(scale_(config->min_width_top_surface.get_abs_value(unscale_(perimeter_width)))) / 4.f);
 
-            top_expolygons = diff_ex(infill_contour, upper_slices_clipped);
+            // Get top ExPolygons from the given contour. uncovered reports whether the upper layer leaves any of the
+            // contour uncovered, before bridges and too thin areas are filtered out.
+            auto get_top_expolygons = [&](const ExPolygons &contour, bool &uncovered) {
+                // Contour bounding box.
+                BoundingBox contour_bbox = get_extents(contour);
+                contour_bbox.offset(SCALED_EPSILON);
+
+                Polygons upper_slices_clipped;
+                if (object_config->interface_shells) {
+                    auto upper_slicer_same_region = to_expolygons(this->upper_slices_same_region->surfaces);
+                    upper_slices_clipped = ClipperUtils::clip_clipper_polygons_with_subject_bbox(upper_slicer_same_region, contour_bbox);
+                } else
+                    upper_slices_clipped = ClipperUtils::clip_clipper_polygons_with_subject_bbox(*upper_slices, contour_bbox);
+
+                ExPolygons top = diff_ex(contour, upper_slices_clipped);
+                uncovered      = !top.empty();
+                if (top.empty())
+                    return top;
 
-            if (!top_expolygons.empty()) {
                 if (lower_slices != nullptr) {
                     const float      bridge_offset          = float(std::max<coord_t>(ext_perimeter_spacing, perimeter_width));
-                    const Polygons   lower_slices_clipped   = ClipperUtils::clip_clipper_polygons_with_subject_bbox(*lower_slices, infill_contour_bbox);
-                    const ExPolygons current_slices_bridges = offset_ex(diff_ex(top_expolygons, lower_slices_clipped), bridge_offset);
+                    const Polygons   lower_slices_clipped   = ClipperUtils::clip_clipper_polygons_with_subject_bbox(*lower_slices, contour_bbox);
+                    const ExPolygons current_slices_bridges = offset_ex(diff_ex(top, lower_slices_clipped), bridge_offset);
 
                     // Remove bridges from top surface polygons.
-                    top_expolygons = diff_ex(top_expolygons, current_slices_bridges);
+                    top = diff_ex(top, current_slices_bridges);
                 }
 
-                // Filter out areas that are too thin and expand top surface polygons a bit to hide the wall line.
-                // ORCA: skip if the top surface area is smaller than "min_width_top_surface"
-                const float top_surface_min_width = std::max<float>(float(ext_perimeter_spacing) / 4.f + scaled<float>(0.00001), float(scale_(config->min_width_top_surface.get_abs_value(unscale_(perimeter_width)))) / 4.f);
                 // Shrink the polygon to remove the small areas, then expand it back out plus a maragin to hide the wall line a little.
                 // ORCA: Expand the polygon with half the perimeter width in addition to the contracted amount,
                 // not the full perimeter width as PS does, to enable thin lettering to print on the top surface without nozzle collisions
                 // due to thin lines being generated
-                top_expolygons = offset2_ex(top_expolygons, -top_surface_min_width, top_surface_min_width + float(perimeter_width * 0.85));
+                top = offset2_ex(top, -top_surface_min_width, top_surface_min_width + float(perimeter_width * 0.85));
 
                 // Get final top ExPolygons (bridges were excluded above, so they stay walled).
-                top_expolygons = intersection_ex(top_expolygons, infill_contour);
+                return intersection_ex(top, contour);
+            };
 
+            // Walls with the full count, as generated when the single perimeter feature is disabled. Generated on first use.
+            std::vector<Arachne::VariableWidthLines> full_perimeters;
+            Polygons                                 full_inner_contour;
+            bool                                     full_perimeters_generated = false;
+            auto generate_full_perimeters = [&]() {
+                if (full_perimeters_generated)
+                    return;
+                Arachne::WallToolPaths full_tool_paths(last_p, bead_width_0, perimeter_spacing, coord_t(inner_loop_number + 2), wall_0_inset, layer_height, input_params_tmp);
+                full_perimeters           = full_tool_paths.getToolPaths();
+                full_inner_contour        = full_tool_paths.getInnerContour();
+                full_perimeters_generated = true;
+            };
+
+            // ORCA: the single wall pass allows Arachne 2 beads across a wall, so it fills a wall narrower than 3 outer wall
+            // widths by widening both, where the full pass adds a middle bead. Over the top surface that is the intent;
+            // anywhere else it leaves no room for the inner walls. When the single wall pass's outer walls run away from
+            // the full pass's outside the top surface, take the full pass's outer walls and the area inside them instead.
+            // Walls closer than outer_wall_tolerance count as the same wall: a widened bead's centerline moves by half
+            // the width added, and only beads widened by more than twice the tolerance are looked for.
+            const coord_t outer_wall_tolerance = bead_width_0 / 10;
+            if (widest_bead(perimeters) > bead_width_0 + 2 * outer_wall_tolerance) {
+                // The single wall pass's inner contour where it widens no bead: inside nominal width outer walls.
+                const ExPolygons nominal_infill_contour = offset_ex(last, -float(bead_width_0 + wall_0_inset));
+                bool             nominal_uncovered      = false;
+                // Grown by an outer wall width to take in the outer walls bordering the top surface.
+                const ExPolygons top_zone = offset_ex(get_top_expolygons(nominal_infill_contour, nominal_uncovered), float(bead_width_0));
+                if (nominal_uncovered) {
+                    generate_full_perimeters();
+                    if (! full_perimeters.empty() && ! full_perimeters.front().empty() &&
+                        length_off_reference(perimeters, full_perimeters.front(), top_zone, outer_wall_tolerance) > double(perimeter_width)) {
+                        perimeters     = { full_perimeters.front() };
+                        infill_contour = diff_ex(nominal_infill_contour, walls_footprint(full_perimeters.front()), ApplySafetyOffset::Yes);
+                    }
+                }
+            }
+
+            bool uncovered = false;
+            top_expolygons = get_top_expolygons(infill_contour, uncovered);
+
+            if (uncovered) {
                 // ORCA: onion the real region (inside the outer wall) so the remaining walls follow the actual
                 // geometry, then cut away the parts over the top surface. Re-onioning the non-top complement
                 // instead - the fallback when there is no top fill - walls the top/non-top interface and rings
@@ -2612,11 +2711,11 @@ void PerimeterGenerator::process_arachne()
                 perimeters.insert(perimeters.end(), inner_perimeters.begin(), inner_perimeters.end());
                 infill_contour = union_ex(top_expolygons, inner_wall_tool_paths.getInnerContour());
             } else {
-                // There is no top surface ExPolygon, so we call Arachne again with parameters
-                // like when the single perimeter feature is disabled.
-                Arachne::WallToolPaths no_single_perimeter_tool_paths(last_p, bead_width_0, perimeter_spacing, coord_t(inner_loop_number + 2), wall_0_inset, layer_height, input_params_tmp);
-                perimeters     = no_single_perimeter_tool_paths.getToolPaths();
-                infill_contour = union_ex(no_single_perimeter_tool_paths.getInnerContour());
+                // There is no top surface ExPolygon, so use the walls generated like when the single perimeter
+                // feature is disabled.
+                generate_full_perimeters();
+                perimeters     = std::move(full_perimeters);
+                infill_contour = union_ex(full_inner_contour);
             }
         }
         //PS

src/slic3r/GUI/GLCanvas3D.cpp

@@ -7970,9 +7970,16 @@ void GLCanvas3D::_render_fps_overlay(int fps) const
     const float margin = 10.0f * get_scale();
     const ImVec2 display_size = ImGui::GetIO().DisplaySize;
     ImVec2 pos(display_size.x - margin, margin);
+    // Last frame's size; zero until the overlay has been shown once.
+    const ImGuiWindow* self = ImGui::FindWindowByName("###fps_overlay");
+    const float left = pos.x - (self != nullptr ? self->Size.x : 0.0f);
     // The Preview legend takes the top-right corner.
     if (const ImGuiWindow* legend = ImGui::FindWindowByName("Legend"); m_canvas_type == ECanvasType::CanvasPreview && legend != nullptr && legend->Active)
         pos = ImVec2(legend->Pos.x - margin, legend->Pos.y);
+    // The toolbar row can reach the corner on a narrow canvas; stack the overlay below it then.
+    else if (m_main_toolbar.is_enabled() &&
+             get_main_toolbar_offset() + m_main_toolbar.get_width() + m_separator_toolbar.get_width() + m_gizmos.get_scaled_total_width() + m_assemble_view_toolbar.get_width() > left)
+        pos.y = std::max(m_main_toolbar.get_height(), m_gizmos.get_scaled_total_height()) + margin;
     ImGui::SetNextWindowPos(pos, ImGuiCond_Always, ImVec2(1.0f, 0.0f));
     ImGui::SetNextWindowBgAlpha(0.35f);
     ImGui::PushStyleVar(ImGuiStyleVar_WindowRounding, 8.0f * get_scale());

src/slic3r/GUI/ReleaseNote.cpp

@@ -1816,7 +1816,10 @@ void InputIpAddressDialog::set_machine_obj(MachineObject* obj)
     m_input_printer_name->GetTextCtrl()->SetLabelText(m_obj->get_dev_name());
 
     std::string img_str = DevPrinterConfigUtil::get_printer_connect_help_img(m_obj->printer_type);
-    auto diagram_bmp = create_scaled_bitmap(img_str + "_en", this, 198);
+    if (img_str.empty()) { img_str = "input_access_code_x1"; }
+
+    std::string language = wxGetApp().app_config->get("language");
+    auto diagram_bmp = create_scaled_bitmap(img_str + (language == "zh_CN" ? "_cn" : "_en"), this, 198);
     m_img_help->SetBitmap(diagram_bmp);
 
 

src/slic3r/GUI/Tab.cpp

@@ -2928,7 +2928,7 @@ void TabPrint::build()
         optgroup->append_single_option_line("skin_infill_line_width", "strength_settings_patterns#locked-zag");
         optgroup->append_single_option_line("skeleton_infill_line_width", "strength_settings_patterns#locked-zag");
         optgroup->append_single_option_line("symmetric_infill_y_axis", "strength_settings_infill#symmetric-infill-y-axis");
-        optgroup->append_single_option_line("infill_complete_top", "strength_settings_infill#infill-complete-top");
+        optgroup->append_single_option_line("infill_complete_top", "strength_settings_patterns#fill-pattern-tops");
         optgroup->append_single_option_line("infill_shift_step", "strength_settings_patterns#cross-hatch");
         optgroup->append_single_option_line("lateral_lattice_angle_1", "strength_settings_patterns#lateral-lattice");
         optgroup->append_single_option_line("lateral_lattice_angle_2", "strength_settings_patterns#lateral-lattice");

src/slic3r/GUI/wxExtensions.cpp

@@ -456,6 +456,13 @@ wxBitmap create_scaled_bitmap(  const std::string& bmp_name_in,
                                 const vector<std::string>& array_new_color/* = vector<std::string>*/)//used for semi transparent material)
 {
     static Slic3r::GUI::BitmapCache cache;
+
+    // An empty name means the caller's icon lookup failed
+    if (bmp_name_in.empty() || bmp_name_in == ".png") {
+        BOOST_LOG_TRIVIAL(error) << __FUNCTION__ << ": empty bitmap name";
+        return wxNullBitmap;
+    }
+
     if (bitmap2) {
         return create_scaled_bitmap2(bmp_name_in, cache, win, px_cnt, grayscale, resize, array_new_color);
     }

tests/fff_print/test_gcodeprocessor.cpp

@@ -1,15 +1,20 @@
 #include <catch2/catch_all.hpp>
 
+#include <catch2/catch_message.hpp>
 #include <catch2/catch_test_macros.hpp>
 #include <catch2/generators/catch_generators.hpp>
 #include <catch2/matchers/catch_matchers.hpp>
 #include <catch2/matchers/catch_matchers_floating_point.hpp>
 #include "libslic3r/libslic3r.h"
+#include "libslic3r/Config.hpp"
 #include "libslic3r/GCode/GCodeProcessor.hpp"
+#include "libslic3r/Model.hpp"
 #include "libslic3r/Utils.hpp"
 
+#include "test_helpers.hpp"
 #include "test_utils.hpp"
 
+#include <algorithm>
 #include <cstddef>
 #include <fstream>
 #include "libslic3r/PrintConfig.hpp"
@@ -177,3 +182,42 @@ TEST_CASE("A seam takes the actual speed of the move it follows", "[GCodeProcess
         }
     REQUIRE(seams > 0);
 }
+
+TEST_CASE("Line ends of the exported G-code mark every newline in the file", "[GCodeProcessor]")
+{
+    struct Case
+    {
+        const char* name;
+        bool        preheat_backtrace;
+        bool        pre_heating;
+    };
+    const auto test_case = GENERATE(values<Case>({
+        { "written by size", false, false },
+        { "written by time for the preheat backtrace", true, false },
+        { "rewritten by the pre-heating pass", false, true },
+    }));
+    INFO(test_case.name);
+    DynamicPrintConfig config = Test::multifilament_config(2, {
+        { "single_extruder_multi_material", 0 },
+        { "ooze_prevention",                test_case.preheat_backtrace },
+        { "preheat_time",                   30 },
+        { "enable_pre_heating",             test_case.pre_heating },
+    });
+    Print print;
+    Model model;
+    const std::vector<std::vector<ConfigBase::SetDeserializeItem>> overrides{ { { "extruder", 1 } }, { { "extruder", 2 } } };
+    Test::init_print({ Test::cube(20), Test::cube(20) }, print, model, config, &overrides);
+    GCodeProcessorResult result;
+    const std::string    gcode = Test::gcode(print, &result);
+    REQUIRE((gcode.find("preheat T") != std::string::npos) == test_case.preheat_backtrace);
+    REQUIRE((gcode.find(GCodeProcessor::Machine_Start_GCode_End_Tag) != std::string::npos) == test_case.pre_heating);
+    REQUIRE(gcode.size() > GCodeProcessor::Output_Block_Size);
+
+    std::vector<size_t> newline_ends;
+    for (size_t i = gcode.find('\n'); i != std::string::npos; i = gcode.find('\n', i + 1))
+        newline_ends.push_back(i + 1);
+    REQUIRE(result.lines_ends.size() == newline_ends.size());
+    const auto difference = std::mismatch(result.lines_ends.begin(), result.lines_ends.end(), newline_ends.begin());
+    INFO("first difference at line " << difference.first - result.lines_ends.begin() + 1);
+    CHECK(difference.first == result.lines_ends.end());
+}

tests/fff_print/test_helpers.cpp

@@ -14,6 +14,7 @@
 #include <initializer_list>
 #include "libslic3r/Point.hpp"
 #include <fstream>
+#include <ios>
 #include <iterator>
 #include <set>
 #include <string>
@@ -330,13 +331,13 @@ void init_and_process_print(std::initializer_list<TriangleMesh> meshes, Slic3r::
 	print.process();
 }
 
-std::string gcode(Print & print)
+std::string gcode(Print & print, GCodeProcessorResult* result)
 {
     ScopedTemporaryFile temp(".gcode");
     print.set_status_silent();
     print.process();
-    print.export_gcode(temp.string(), nullptr, nullptr);
-    std::ifstream t(temp.string());
+    print.export_gcode(temp.string(), result, nullptr);
+    std::ifstream t(temp.string(), std::ios::binary);
 	std::string str((std::istreambuf_iterator<char>(t)), std::istreambuf_iterator<char>());
 	return str;
 }

tests/fff_print/test_helpers.hpp

@@ -17,7 +17,9 @@
 #include <unordered_map>
 #include <vector>
 
-namespace Slic3r { namespace Test {
+namespace Slic3r {
+struct GCodeProcessorResult;
+namespace Test {
 
 constexpr double MM_PER_MIN = 60.0;
 
@@ -92,8 +94,8 @@ void init_and_process_print(std::initializer_list<TriangleMesh> meshes, Slic3r::
 void init_and_process_print(std::initializer_list<TestMesh> meshes, Slic3r::Print &print, std::initializer_list<Slic3r::ConfigBase::SetDeserializeItem> config_items);
 void init_and_process_print(std::initializer_list<TriangleMesh> meshes, Slic3r::Print &print, std::initializer_list<Slic3r::ConfigBase::SetDeserializeItem> config_items);
 
-// Process `print` and return its exported G-code.
-std::string gcode(Print& print);
+// Process `print` and return its exported G-code, filling `result` when one is given.
+std::string gcode(Print& print, GCodeProcessorResult* result = nullptr);
 
 // Build, slice, and return the G-code for `meshes` under the given config.
 std::string slice(std::initializer_list<TestMesh> meshes, const DynamicPrintConfig &config);

tests/fff_print/test_perimeters.cpp

@@ -19,8 +19,10 @@
 #include <cstddef>
 #include "libslic3r/libslic3r.h"
 #include "libslic3r/BoundingBox.hpp"
+#include "libslic3r/ClipperUtils.hpp"
 #include "libslic3r/ExPolygon.hpp"
 #include "libslic3r/Point.hpp"
+#include "libslic3r/Polyline.hpp"
 #include <limits>
 #include <string>
 #include <utility>
@@ -275,6 +277,124 @@ TEST_CASE("Only one wall on the first layer needs a bottom shell", "[Perimeters]
 
 namespace {
 
+// The last layer of the tab, whose top surface shares an island with the tube walls rising past it.
+const double tab_top_z = 5.0;
+
+// With the widths below the tube walls are 1.10mm wide once the precise outer wall offset (0.043mm a side) is
+// taken off. That is narrower than 3 outer wall spacings (3 x 0.377 = 1.131mm), so an Arachne pass limited to a
+// single wall fills it by widening its 2 beads, yet wide enough for the full 2 wall pass to add a middle wall
+// (from 1.062mm).
+const double narrow_wall = 1.186;
+
+// A 20x30x10 tube with narrow_wall thick walls, and a 20x8x5 tab against its -Y side.
+Print &tube_with_tab(Print &print, Model &model, const DynamicPrintConfig &config)
+{
+    ModelObject *object = model.add_object();
+    object->name = "tube_with_tab.stl";
+    object->add_volume(make_cube(20., 30., 10.), ModelVolumeType::MODEL_PART, false);
+    // Overlaps the tube wall by 0.5mm so the two parts slice as one island.
+    TriangleMesh tab = make_cube(20., 8.5, 5.);
+    tab.translate(0.f, -8.f, 0.f);
+    object->add_volume(std::move(tab), ModelVolumeType::MODEL_PART, false);
+    TriangleMesh bore = make_cube(20. - 2. * narrow_wall, 30. - 2. * narrow_wall, 12.);
+    bore.translate(float(narrow_wall), float(narrow_wall), -1.f);
+    object->add_volume(std::move(bore), ModelVolumeType::NEGATIVE_VOLUME, false);
+    object->add_instance();
+    object->ensure_on_bed();
+
+    print.auto_assign_extruders(object);
+    print.apply(model, config);
+    print.validate();
+    print.set_status_silent();
+    return print;
+}
+
+// Every width the narrow_wall arithmetic depends on, so none of them rests on a default.
+DynamicPrintConfig narrow_wall_config(bool only_one_wall_top, double top_surface_expansion)
+{
+    DynamicPrintConfig config = base_config("arachne");
+    config.set_deserialize_strict({
+        { "wall_loops",            2 },
+        { "nozzle_diameter",       "0.4" },
+        { "line_width",            0.42 },
+        { "outer_wall_line_width", 0.42 },
+        { "inner_wall_line_width", 0.45 },
+        { "min_bead_width",        "85%" },
+        { "precise_outer_wall",    true },
+        { "wall_sequence",         "inner wall/outer wall" },
+        { "only_one_wall_top",     only_one_wall_top },
+        { "top_surface_expansion", top_surface_expansion },
+    });
+    return config;
+}
+
+// Inner wall length the layer at print_z extrudes within 3mm of its +Y edge: the tube wall facing away from the tab.
+double far_wall_inner_wall_length(const Print &print, double print_z)
+{
+    for (const Layer *layer : print.objects().front()->layers()) {
+        if (std::abs(layer->print_z - print_z) > EPSILON)
+            continue;
+        BoundingBox band = get_extents(layer->lslices);
+        band.min.y()     = band.max.y() - scaled<coord_t>(3.);
+
+        Polylines inner_walls;
+        auto      collect = [&inner_walls](const ExtrusionPaths &paths) {
+            for (const ExtrusionPath &path : paths)
+                if (path.role() == erPerimeter)
+                    inner_walls.emplace_back(path.as_polyline());
+        };
+        for (const LayerRegion *region : layer->regions()) {
+            const ExtrusionEntityCollection walls = region->perimeters.flatten();
+            for (const ExtrusionEntity *entity : walls.entities) {
+                if (const auto *loop = dynamic_cast<const ExtrusionLoop*>(entity))
+                    collect(loop->paths);
+                else if (const auto *multi_path = dynamic_cast<const ExtrusionMultiPath*>(entity))
+                    collect(multi_path->paths);
+                else if (const auto *path = dynamic_cast<const ExtrusionPath*>(entity))
+                    collect({ *path });
+            }
+        }
+        return unscaled<double>(total_length(intersection_pl(inner_walls, band.polygon())));
+    }
+    return 0.;
+}
+
+} // namespace
+
+// only_one_wall_top first lays out an island with a single Arachne wall and generates the inner walls inside it.
+// On a wall narrower than 3 outer wall spacings that single wall pass widens its 2 beads to fill the wall and leaves
+// no room for the middle wall, which is only intended over the top surface. The tube walls away from the tab are not
+// under the tab's top surface, so on the tab's last layer they keep the inner wall they get with the option off.
+TEST_CASE("Only one wall on top surfaces keeps the inner walls of narrow walls away from the top surface", "[Perimeters]")
+{
+    // 0 re-onions the region beside the top surface, 2 clips the inner walls over it.
+    const double top_surface_expansion = GENERATE(0.0, 2.0);
+    CAPTURE(top_surface_expansion);
+
+    struct TabTopLayer {
+        double perimeters;
+        double far_wall_inner_walls;
+    };
+    auto tab_top_layer_for = [top_surface_expansion](bool only_one_wall_top) {
+        Print print;
+        Model model;
+        tube_with_tab(print, model, narrow_wall_config(only_one_wall_top, top_surface_expansion));
+        print.process();
+        REQUIRE_FALSE(print.objects().empty());
+        return TabTopLayer{ perimeter_length_at(print, tab_top_z), far_wall_inner_wall_length(print, tab_top_z) };
+    };
+
+    const TabTopLayer plain    = tab_top_layer_for(false);
+    const TabTopLayer one_wall = tab_top_layer_for(true);
+
+    // The option acts on this layer: the inner walls under the tab's top surface are gone.
+    REQUIRE(plain.far_wall_inner_walls > 10.);
+    CHECK(one_wall.perimeters < plain.perimeters);
+    CHECK_THAT(one_wall.far_wall_inner_walls, Catch::Matchers::WithinAbs(plain.far_wall_inner_walls, 1.0));
+}
+
+namespace {
+
 // The layer that closes the cavity of box_over_cavity(), the first one printed over air.
 const double cavity_ceiling_z = 6.2;