[smart_holder] git merge master

.github/workflows/ci.yml

@@ -502,7 +502,9 @@ jobs:
           - { gcc: 7, std: 17 }
           - { gcc: 8, std: 14 }
           - { gcc: 8, std: 17 }
+          - { gcc: 9, std: 20 }
           - { gcc: 10, std: 17 }
+          - { gcc: 10, std: 20 }
           - { gcc: 11, std: 20 }
           - { gcc: 12, std: 20 }
           - { gcc: 13, std: 20 }

.github/workflows/ci_sh_def.yml

@@ -520,7 +520,9 @@ jobs:
           - { gcc: 7, std: 17 }
           - { gcc: 8, std: 14 }
           - { gcc: 8, std: 17 }
+          - { gcc: 9, std: 20 }
           - { gcc: 10, std: 17 }
+          - { gcc: 10, std: 20 }
           - { gcc: 11, std: 20 }
           - { gcc: 12, std: 20 }
           - { gcc: 13, std: 20 }

.github/workflows/ci_sh_def.yml.patch

@@ -1,5 +1,5 @@
---- ci.yml	2024-06-21 22:56:01.205982412 -0700
-+++ ci_sh_def.yml	2024-06-21 22:57:45.189902320 -0700
+--- ci.yml	2024-07-01 20:26:45.034547517 -0700
++++ ci_sh_def.yml	2024-07-01 20:27:32.110506039 -0700
 @@ -1,4 +1,16 @@
 -name: CI
 +# PLEASE KEEP THIS GROUP OF FILES IN SYNC AT ALL TIMES:
@@ -93,127 +93,127 @@
                              -DPYBIND11_TEST_FILTER="test_smart_ptr.cpp"
 
      - name: Build
-@@ -529,6 +547,7 @@
+@@ -531,6 +549,7 @@
          -DPYBIND11_WERROR=ON
          -DDOWNLOAD_CATCH=ON
          -DCMAKE_CXX_STANDARD=${{ matrix.std }}
 +        -DCMAKE_CXX_FLAGS="-DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT"
          -DPYTHON_EXECUTABLE=$(python3 -c "import sys; print(sys.executable)")
 
      - name: Build
-@@ -551,6 +570,7 @@
+@@ -553,6 +572,7 @@
          -DPYBIND11_WERROR=ON
          -DDOWNLOAD_CATCH=ON
          -DCMAKE_CXX_STANDARD=${{ matrix.std }}
 +        -DCMAKE_CXX_FLAGS="-DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT"
          -DPYTHON_EXECUTABLE=$(python3 -c "import sys; print(sys.executable)")
          "-DPYBIND11_TEST_OVERRIDE=test_call_policies.cpp;test_gil_scoped.cpp;test_thread.cpp"
 
-@@ -600,6 +620,7 @@
+@@ -602,6 +622,7 @@
          -DDOWNLOAD_CATCH=ON     \
          -DDOWNLOAD_EIGEN=OFF    \
          -DCMAKE_CXX_STANDARD=11             \
 +        -DCMAKE_CXX_FLAGS="-DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT"  \
          -DCMAKE_CXX_COMPILER=$(which icpc)  \
          -DPYTHON_EXECUTABLE=$(python3 -c "import sys; print(sys.executable)")
 
-@@ -632,6 +653,7 @@
+@@ -634,6 +655,7 @@
          -DDOWNLOAD_CATCH=ON     \
          -DDOWNLOAD_EIGEN=OFF    \
          -DCMAKE_CXX_STANDARD=17             \
 +        -DCMAKE_CXX_FLAGS="-DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT"  \
          -DCMAKE_CXX_COMPILER=$(which icpc)  \
          -DPYTHON_EXECUTABLE=$(python3 -c "import sys; print(sys.executable)")
 
-@@ -703,6 +725,7 @@
+@@ -705,6 +727,7 @@
          -DDOWNLOAD_CATCH=ON
          -DDOWNLOAD_EIGEN=ON
          -DCMAKE_CXX_STANDARD=11
 +        -DCMAKE_CXX_FLAGS="-DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT"
          -DPYTHON_EXECUTABLE=$(python3 -c "import sys; print(sys.executable)")
 
      - name: Build
-@@ -753,6 +776,7 @@
+@@ -755,6 +778,7 @@
          cmake ../pybind11-tests
          -DDOWNLOAD_CATCH=ON
          -DPYBIND11_WERROR=ON
 +        -DCMAKE_CXX_FLAGS="-DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT"
          -DPYTHON_EXECUTABLE=$(python3 -c "import sys; print(sys.executable)")
        working-directory: /build-tests
 
-@@ -856,6 +880,7 @@
+@@ -858,6 +882,7 @@
          -DPYBIND11_WERROR=ON
          -DDOWNLOAD_CATCH=ON
          -DDOWNLOAD_EIGEN=ON
 +        -DCMAKE_CXX_FLAGS="/GR /EHsc /DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT"
          ${{ matrix.args }}
      - name: Build C++11
        run: cmake --build build -j 2
-@@ -910,6 +935,7 @@
+@@ -912,6 +937,7 @@
          -DPYBIND11_WERROR=ON
          -DDOWNLOAD_CATCH=ON
          -DDOWNLOAD_EIGEN=ON
 +        -DCMAKE_CXX_FLAGS="/GR /EHsc /DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT"
          ${{ matrix.args }}
      - name: Build C++11
        run: cmake --build build --config Debug -j 2
-@@ -952,6 +978,7 @@
+@@ -954,6 +980,7 @@
          -DDOWNLOAD_CATCH=ON
          -DDOWNLOAD_EIGEN=ON
          -DCMAKE_CXX_STANDARD=20
 +        -DCMAKE_CXX_FLAGS="/GR /EHsc /DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT"
 
      - name: Build C++20
        run: cmake --build build -j 2
-@@ -972,6 +999,7 @@
+@@ -974,6 +1001,7 @@
          -DDOWNLOAD_CATCH=ON
          -DDOWNLOAD_EIGEN=ON
          -DCMAKE_CXX_STANDARD=20
 +        -DCMAKE_CXX_FLAGS="/GR /EHsc /DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT"
          "-DPYBIND11_TEST_OVERRIDE=test_call_policies.cpp;test_gil_scoped.cpp;test_thread.cpp"
 
      - name: Build C++20 - Exercise cmake -DPYBIND11_TEST_OVERRIDE
-@@ -1024,6 +1052,7 @@
+@@ -1026,6 +1054,7 @@
        run: >-
          cmake -G "MinGW Makefiles" -DCMAKE_CXX_STANDARD=11 -DPYBIND11_WERROR=ON -DDOWNLOAD_CATCH=ON
          -DPYTHON_EXECUTABLE=$(python -c "import sys; print(sys.executable)")
 +        -DCMAKE_CXX_FLAGS="-DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT"
          -S . -B build
 
      - name: Build C++11
-@@ -1045,6 +1074,7 @@
+@@ -1047,6 +1076,7 @@
        run: >-
          cmake -G "MinGW Makefiles" -DCMAKE_CXX_STANDARD=14 -DPYBIND11_WERROR=ON -DDOWNLOAD_CATCH=ON
          -DPYTHON_EXECUTABLE=$(python -c "import sys; print(sys.executable)")
 +        -DCMAKE_CXX_FLAGS="-DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT"
          -S . -B build2
 
      - name: Build C++14
-@@ -1066,6 +1096,7 @@
+@@ -1068,6 +1098,7 @@
        run: >-
          cmake -G "MinGW Makefiles" -DCMAKE_CXX_STANDARD=17 -DPYBIND11_WERROR=ON -DDOWNLOAD_CATCH=ON
          -DPYTHON_EXECUTABLE=$(python -c "import sys; print(sys.executable)")
 +        -DCMAKE_CXX_FLAGS="-DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT"
          -S . -B build3
 
      - name: Build C++17
-@@ -1133,6 +1164,7 @@
+@@ -1135,6 +1166,7 @@
            -DDOWNLOAD_EIGEN=ON
            -DCMAKE_CXX_COMPILER=clang++
            -DCMAKE_CXX_STANDARD=17
 +          -DCMAKE_CXX_FLAGS="-DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT"
 
        - name: Build
          run: cmake --build . -j 2
-@@ -1198,6 +1230,7 @@
+@@ -1200,6 +1232,7 @@
            -DDOWNLOAD_EIGEN=ON
            -DCMAKE_CXX_COMPILER=clang++
            -DCMAKE_CXX_STANDARD=17
 +          -DCMAKE_CXX_FLAGS="-DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT"
            -DPYTHON_EXECUTABLE=$(python3 -c "import sys; print(sys.executable)")
 
        - name: Build
-@@ -1221,6 +1254,7 @@
+@@ -1223,6 +1256,7 @@
            -DDOWNLOAD_EIGEN=ON
            -DCMAKE_CXX_COMPILER=clang++
            -DCMAKE_CXX_STANDARD=17

.github/workflows/pip.yml

@@ -103,7 +103,7 @@ jobs:
     - uses: actions/download-artifact@v4
 
     - name: Generate artifact attestation for sdist and wheel
-      uses: actions/attest-build-provenance@173725a1209d09b31f9d30a3890cf2757ebbff0d # v1.1.2
+      uses: actions/attest-build-provenance@bdd51370e0416ac948727f861e03c2f05d32d78e # v1.3.2
       with:
         subject-path: "*/pybind11*"
 

include/pybind11/cast.h

@@ -770,6 +770,13 @@ class type_caster<std::pair<T1, T2>> : public tuple_caster<std::pair, T1, T2> {}
 template <typename... Ts>
 class type_caster<std::tuple<Ts...>> : public tuple_caster<std::tuple, Ts...> {};
 
+template <>
+class type_caster<std::tuple<>> : public tuple_caster<std::tuple> {
+public:
+    // PEP 484 specifies this syntax for an empty tuple
+    static constexpr auto name = const_name("tuple[()]");
+};
+
 /// Helper class which abstracts away certain actions. Users can provide specializations for
 /// custom holders, but it's only necessary if the type has a non-standard interface.
 template <typename T>

include/pybind11/typing.h

@@ -14,6 +14,8 @@
 #include "cast.h"
 #include "pytypes.h"
 
+#include <algorithm>
+
 PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
 PYBIND11_NAMESPACE_BEGIN(typing)
 
@@ -98,7 +100,10 @@ class Never : public none {
     using none::none;
 };
 
-#if defined(__cpp_nontype_template_parameter_class)
+#if defined(__cpp_nontype_template_parameter_class)                                               \
+    && (/* See #5201 */ !defined(__GNUC__)                                                        \
+        || (__GNUC__ > 10 || (__GNUC__ == 10 && __GNUC_MINOR__ >= 3)))
+#    define PYBIND11_TYPING_H_HAS_STRING_LITERAL
 template <size_t N>
 struct StringLiteral {
     constexpr StringLiteral(const char (&str)[N]) { std::copy_n(str, N, name); }
@@ -222,7 +227,7 @@ struct handle_type_name<typing::Never> {
     static constexpr auto name = const_name("Never");
 };
 
-#if defined(__cpp_nontype_template_parameter_class)
+#if defined(PYBIND11_TYPING_H_HAS_STRING_LITERAL)
 template <typing::StringLiteral... Literals>
 struct handle_type_name<typing::Literal<Literals...>> {
     static constexpr auto name = const_name("Literal[")

tests/test_builtin_casters.py

@@ -368,6 +368,8 @@ def test_tuple(doc):
     """
     )
 
+    assert doc(m.empty_tuple) == """empty_tuple() -> tuple[()]"""
+
     assert m.rvalue_pair() == ("rvalue", "rvalue")
     assert m.lvalue_pair() == ("lvalue", "lvalue")
     assert m.rvalue_tuple() == ("rvalue", "rvalue", "rvalue")

tests/test_pytypes.cpp

@@ -109,7 +109,7 @@ void m_defs(py::module_ &m) {
 
 } // namespace handle_from_move_only_type_with_operator_PyObject
 
-#if defined(__cpp_nontype_template_parameter_class)
+#if defined(PYBIND11_TYPING_H_HAS_STRING_LITERAL)
 namespace literals {
 enum Color { RED = 0, BLUE = 1 };
 
@@ -905,7 +905,7 @@ TEST_SUBMODULE(pytypes, m) {
     m.def("annotate_optional_to_object",
           [](py::typing::Optional<int> &o) -> py::object { return o; });
 
-#if defined(__cpp_nontype_template_parameter_class)
+#if defined(PYBIND11_TYPING_H_HAS_STRING_LITERAL)
     py::enum_<literals::Color>(m, "Color")
         .value("RED", literals::Color::RED)
         .value("BLUE", literals::Color::BLUE);
@@ -919,8 +919,8 @@ TEST_SUBMODULE(pytypes, m) {
     m.def("annotate_listT_to_T",
           [](const py::typing::List<typevar::TypeVarT> &l) -> typevar::TypeVarT { return l[0]; });
     m.def("annotate_object_to_T", [](const py::object &o) -> typevar::TypeVarT { return o; });
-    m.attr("if_defined__cpp_nontype_template_parameter_class") = true;
+    m.attr("defined_PYBIND11_TYPING_H_HAS_STRING_LITERAL") = true;
 #else
-    m.attr("if_defined__cpp_nontype_template_parameter_class") = false;
+    m.attr("defined_PYBIND11_TYPING_H_HAS_STRING_LITERAL") = false;
 #endif
 }

tests/test_pytypes.py

@@ -1025,7 +1025,7 @@ def test_optional_object_annotations(doc):
 
 
 @pytest.mark.skipif(
-    not m.if_defined__cpp_nontype_template_parameter_class,
+    not m.defined_PYBIND11_TYPING_H_HAS_STRING_LITERAL,
     reason="C++20 feature not available.",
 )
 def test_literal(doc):
@@ -1036,7 +1036,7 @@ def test_literal(doc):
 
 
 @pytest.mark.skipif(
-    not m.if_defined__cpp_nontype_template_parameter_class,
+    not m.defined_PYBIND11_TYPING_H_HAS_STRING_LITERAL,
     reason="C++20 feature not available.",
 )
 def test_typevar(doc):

tools/pybind11Common.cmake

@@ -335,7 +335,7 @@ function(_pybind11_generate_lto target prefer_thin_lto)
       set(PYBIND11_LTO_LINKER_FLAGS "-flto${thin}${linker_append}")
     elseif(CMAKE_CXX_COMPILER_ID MATCHES "Clang")
       _pybind11_return_if_cxx_and_linker_flags_work(
-        HAS_FLTO_THIN "-flto${thin}${cxx_append}" "-flto=${thin}${linker_append}"
+        HAS_FLTO_THIN "-flto${thin}${cxx_append}" "-flto${thin}${linker_append}"
         PYBIND11_LTO_CXX_FLAGS PYBIND11_LTO_LINKER_FLAGS)
     endif()
     if(NOT HAS_FLTO_THIN)