Uniformly disable assertions on release builds and enable them for tests

.github/workflows/ci.yaml

@@ -188,6 +188,9 @@ jobs:
           cd .. && \
           rm -rf libffi-3.4.6
         CIBW_ENVIRONMENT_PASS_LINUX: CFLAGS  # ensure that the build container can see our overridden build config
+        CIBW_ENVIRONMENT: >-
+          CPPFLAGS="$CPPFLAGS ${{ env.skip_artifact_upload == 'true' && '-UNDEBUG' || '-DNDEBUG' }}"
+          CFFI_TEST_ASSERTIONS=${{ env.skip_artifact_upload == 'true' && '1' || '0' }}
         CIBW_MANYLINUX_X86_64_IMAGE: ${{ matrix.manylinux_img || 'manylinux2014' }}
         CIBW_MANYLINUX_I686_IMAGE: ${{ matrix.manylinux_img || 'manylinux2014' }}
         CIBW_MANYLINUX_AARCH64_IMAGE: ${{ matrix.manylinux_img || 'manylinux2014' }}
@@ -287,6 +290,9 @@ jobs:
         CIBW_ENABLE: cpython-prerelease
         CIBW_TEST_REQUIRES: pytest setuptools meson-python ninja
         CIBW_TEST_COMMAND: pip install pip --upgrade; cd {project}; PYTHONUNBUFFERED=1 pytest
+        CIBW_ENVIRONMENT: >-
+          CPPFLAGS="$CPPFLAGS ${{ env.skip_artifact_upload == 'true' && '-UNDEBUG' || '-DNDEBUG' }}"
+          CFFI_TEST_ASSERTIONS=${{ env.skip_artifact_upload == 'true' && '1' || '0' }}
         MACOSX_DEPLOYMENT_TARGET: ${{ matrix.deployment_target || '11.0' }}
         SDKROOT: ${{ matrix.sdkroot || 'macosx' }}
       run: |
@@ -375,6 +381,9 @@ jobs:
         CIBW_ENABLE: cpython-prerelease
         CIBW_TEST_REQUIRES: pytest setuptools meson-python ninja
         CIBW_TEST_COMMAND: ${{ matrix.test_cmd || 'python -m pytest {package}/src/c' }}
+        CIBW_ENVIRONMENT: >-
+          _CL_="$_CL_ ${{ env.skip_artifact_upload == 'true' && '/UNDEBUG' || '/DNDEBUG' }}"
+          CFFI_TEST_ASSERTIONS=${{ env.skip_artifact_upload == 'true' && '1' || '0' }}
         # FIXME: /testing takes ~45min on Windows and has some failures...
         # CIBW_TEST_COMMAND='python -m pytest {package}/src/c {package}/testing'
       run: |
@@ -479,9 +488,12 @@ jobs:
         CIBW_TEST_SOURCES: cffi
         # Running tests from `testing/` will not work since they try to compile C code on device
         CIBW_TEST_COMMAND: python -m pytest -sv cffi/src/c/
+        # Xcode forwards TEST_RUNNER_ variables into the simulator test process.
+        CIBW_TEST_ENVIRONMENT: TEST_RUNNER_CFFI_TEST_ASSERTIONS=${{ env.skip_artifact_upload == 'true' && '1' || '0' }}
         # Environment variables for the build
         CIBW_ENVIRONMENT: >
           CFLAGS="-I${LIBFFI_IOS_DIR}/include"
+          CPPFLAGS="$CPPFLAGS ${{ env.skip_artifact_upload == 'true' && '-UNDEBUG' || '-DNDEBUG' }}"
           LDFLAGS="-L${LIBFFI_IOS_DIR}/lib"
           PYTHONUNBUFFERED=1
         # Pass through our custom env vars
@@ -535,6 +547,10 @@ jobs:
 
   pytest-run-parallel:
     needs: make_run_parallel_matrix
+    env:
+      CPPFLAGS: -UNDEBUG
+      _CL_: /UNDEBUG
+      CFFI_TEST_ASSERTIONS: '1'
     strategy:
       fail-fast: false
       matrix: ${{ fromJSON(needs.make_run_parallel_matrix.outputs.matrix_json) }}
@@ -562,13 +578,17 @@ jobs:
   clang_TSAN:
     runs-on: ubuntu-24.04
     container: ghcr.io/nascheme/numpy-tsan:3.15t-dev
+    env:
+      CFLAGS: -g -O0 -fsanitize=thread
+      CPPFLAGS: -UNDEBUG
+      CFFI_TEST_ASSERTIONS: '1'
     steps:
     - uses: actions/checkout@v7
 
     - name: build and install
       run: |
         python -m pip install setuptools meson-python ninja pytest pytest-run-parallel
-        CFLAGS="-g -O3 -fsanitize=thread" python -m pip install -v .
+        python -m pip install -v .
 
     - name: run tests under pytest-run-parallel
       run: |

src/c/_cffi_backend.c

@@ -7585,6 +7585,14 @@ static _cffi_double_complex_t _testfunc25(double a, double b)
 }
 #endif
 
+static int _testfunc26(void)
+{
+    /* Report whether assert expressions are evaluated in this build. */
+    int enabled = 0;
+    assert(++enabled);
+    return enabled;
+}
+
 static PyObject *b__testfunc(PyObject *self, PyObject *args)
 {
     /* for testing only */
@@ -7621,6 +7629,7 @@ static PyObject *b__testfunc(PyObject *self, PyObject *args)
     case 24: f = &_testfunc24; break;
     case 25: f = &_testfunc25; break;
 #endif
+    case 26: f = &_testfunc26; break;
     default:
         PyErr_SetNone(PyExc_ValueError);
         return NULL;

src/c/test_c.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 import contextlib
+import os
 import traceback
 import unittest.mock
 
@@ -1222,6 +1223,16 @@ def test_call_function_23_bool_array():
     assert res == 1000
     pytest.raises(ValueError, f, b"\x02\x02")
 
+def test_backend_assertions():
+    expected = os.environ.get('CFFI_TEST_ASSERTIONS')
+    if expected is None and not os.environ.get('GITHUB_ACTIONS'):
+        pytest.skip("CFFI_TEST_ASSERTIONS is not set")
+    assert expected in ('0', '1')
+    BInt = new_primitive_type("int")
+    BFunc = new_function_type((), BInt, False)
+    f = cast(BFunc, _testfunc(26))
+    assert f() == int(expected)
+
 def test_cannot_pass_struct_with_array_of_length_0():
     BInt = new_primitive_type("int")
     BArray0 = new_array_type(new_pointer_type(BInt), 0)