ci: add GitHub Actions build/test + ASan/UBSan (fix cmake test build)

.github/workflows/ci.yml

@@ -0,0 +1,57 @@
+name: CI
+
+on:
+  push:
+    branches: [master]
+  pull_request:
+
+# Least privilege: the workflow only needs to read the repository. The repo
+# default is `write`, so scope it down explicitly and drop the checkout token
+# after fetch, so pull-request-controlled build/test steps never see a
+# write-capable token.
+permissions:
+  contents: read
+
+jobs:
+  build-and-test:
+    name: build + unit tests (${{ matrix.cc }})
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        cc: [gcc, clang]
+    env:
+      CC: ${{ matrix.cc }}
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          persist-credentials: false
+      - name: Configure
+        run: >
+          cmake -S . -B build
+          -DCMAKE_BUILD_TYPE=Release
+          -DBUILD_TESTS=ON -DBUILD_BENCHMARK=OFF -DBUILD_EXAMPLES=OFF
+      - name: Build
+        run: cmake --build build -j"$(nproc)"
+      - name: Unit tests
+        run: ctest --test-dir build --output-on-failure
+
+  sanitizers:
+    name: ASan + UBSan
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          persist-credentials: false
+      - name: Build td_test with ASan + UBSan
+        run: >
+          clang -O1 -g -std=gnu11
+          -fsanitize=address,undefined -fno-sanitize-recover=all -fno-omit-frame-pointer
+          -Isrc tests/unit/td_test.c src/tdigest.c -lm -o td_test_san
+      - name: Run
+        env:
+          # A fuzzed/huge compression can request an enormous capacity; let the
+          # library's allocation-failure path run instead of aborting the process.
+          ASAN_OPTIONS: detect_leaks=1:allocator_may_return_null=1
+          UBSAN_OPTIONS: print_stacktrace=1:halt_on_error=1
+        run: ./td_test_san

tests/CMakeLists.txt

@@ -16,6 +16,10 @@ endif()
 if (BUILD_TESTS)
     set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -std=c99")
     add_executable(td_test unit/td_test.c unit/minunit.h)
+    # minunit.h uses clock_gettime(), which the top-level "-std=c99" hides unless
+    # _POSIX_C_SOURCE is defined on the command line (before any header is included).
+    # Without this the td_test build fails with "unknown type name 'clockid_t'".
+    target_compile_definitions(td_test PRIVATE _POSIX_C_SOURCE=200809L)
     target_link_libraries(td_test tdigest m)
     enable_testing()
     add_test(td_test td_test)