absl/copts/copts.py

"""Abseil compiler options.

This is the source of truth for Abseil compiler options.  To modify Abseil
compilation options:

  (1) Edit the appropriate list in this file based on the platform the flag is
      needed on.
  (2) Run `<path_to_absl>/copts/generate_copts.py`.

The generated copts are consumed by configure_copts.bzl and
AbseilConfigureCopts.cmake.
"""

ABSL_GCC_FLAGS = [
    "-Wall",
    "-Wextra",
    "-Wcast-qual",
    "-Wconversion-null",
    "-Wformat-security",
    "-Wmissing-declarations",
    "-Wnon-virtual-dtor",
    "-Woverlength-strings",
    "-Wpointer-arith",
    "-Wundef",
    "-Wunused-local-typedefs",
    "-Wunused-result",
    "-Wvarargs",
    "-Wvla",  # variable-length array
    "-Wwrite-strings",
    # Don't define min and max macros (Build on Windows using gcc)
    "-DNOMINMAX",
]

ABSL_GCC_TEST_ADDITIONAL_FLAGS = [
    "-Wno-deprecated-declarations",
    "-Wno-missing-declarations",
    "-Wno-self-move",
    "-Wno-sign-compare",
    "-Wno-unused-function",
    "-Wno-unused-parameter",
    "-Wno-unused-private-field",
]

# https://github.com/llvm/llvm-project/issues/102982
# A list of LLVM base flags without -Wall. This is because clang-cl
# translates -Wall to -Weverything on Windows, mimicking MSVCs
# behavior. On most other platforms, -Wall is just a set of very good
# default flags.
ABSL_LLVM_BASE_FLAGS = [
    "-Wmost",
    "-Wextra",
    "-Wc++98-compat-extra-semi",
    "-Wcast-qual",
    "-Wconversion",
    "-Wdeprecated-pragma",
    "-Wfloat-overflow-conversion",
    "-Wfloat-zero-conversion",
    "-Wfor-loop-analysis",
    "-Wformat-security",
    "-Wgnu-redeclared-enum",
    "-Winfinite-recursion",
    "-Winvalid-constexpr",
    "-Wliteral-conversion",
    "-Wmissing-declarations",
    "-Wnullability-completeness",
    "-Woverlength-strings",
    "-Wpointer-arith",
    "-Wself-assign",
    "-Wshadow-all",
    "-Wshorten-64-to-32",
    "-Wsign-conversion",
    "-Wstring-conversion",
    "-Wtautological-overlap-compare",
    "-Wtautological-unsigned-zero-compare",
    "-Wthread-safety",
    "-Wundef",
    "-Wuninitialized",
    "-Wunreachable-code",
    "-Wunused-comparison",
    "-Wunused-local-typedefs",
    "-Wunused-result",
    "-Wvla",
    "-Wwrite-strings",
    # Warnings that are enabled by group warning flags like -Wall that we
    # explicitly disable.
    "-Wno-float-conversion",
    "-Wno-implicit-float-conversion",
    "-Wno-implicit-int-float-conversion",
    # Disable warnings on unknown warning flags (when warning flags are
    # unknown on older compiler versions)
    "-Wno-unknown-warning-option",
    "-Wno-unused-command-line-argument",
    # Don't define min and max macros (Build on Windows using clang)
    "-DNOMINMAX",
]

ABSL_LLVM_FLAGS = ["-Wall"] + ABSL_LLVM_BASE_FLAGS

ABSL_LLVM_TEST_ADDITIONAL_FLAGS = [
    "-Wno-deprecated-declarations",
    "-Wno-implicit-int-conversion",
    "-Wno-missing-prototypes",
    "-Wno-missing-variable-declarations",
    "-Wno-nullability-completeness",
    "-Wno-shadow",
    "-Wno-shorten-64-to-32",
    "-Wno-sign-compare",
    "-Wno-sign-conversion",
    "-Wno-unreachable-code-loop-increment",
    "-Wno-unused-function",
    "-Wno-unused-member-function",
    "-Wno-unused-parameter",
    "-Wno-unused-private-field",
    "-Wno-unused-template",
    "-Wno-used-but-marked-unused",
    # gtest depends on this GNU extension being offered.
    "-Wno-gnu-zero-variadic-macro-arguments",
]

# /Wall with msvc includes unhelpful warnings such as C4711, C4710, ...
MSVC_BIG_WARNING_FLAGS = [
    "/W3",
]

MSVC_WARNING_FLAGS = [
    # Increase the number of sections available in object files
    "/bigobj",
    "/wd4005",  # macro-redefinition
    "/wd4068",  # unknown pragma
    # qualifier applied to function type has no meaning; ignored
    "/wd4180",
    # The decorated name was longer than the compiler limit
    "/wd4503",
    # forcing value to bool 'true' or 'false' (performance warning)
    "/wd4800",
]

MSVC_DEFINES = [
    "/DNOMINMAX",  # Don't define min and max macros (windows.h)
    # Don't bloat namespace with incompatible winsock versions.
    "/DWIN32_LEAN_AND_MEAN",
    # Don't warn about usage of insecure C functions.
    "/D_CRT_SECURE_NO_WARNINGS",
    "/D_SCL_SECURE_NO_WARNINGS",
    # Introduced in VS 2017 15.8, allow overaligned types in aligned_storage
    "/D_ENABLE_EXTENDED_ALIGNED_STORAGE",
]


def GccStyleFilterAndCombine(default_flags, test_flags):
  """Merges default_flags and test_flags for GCC and LLVM.

  Args:
    default_flags: A list of default compiler flags
    test_flags: A list of flags that are only used in tests

  Returns:
    A combined list of default_flags and test_flags, but with all flags of the
    form '-Wwarning' removed if test_flags contains a flag of the form
    '-Wno-warning'
  """
  remove = set(["-W" + f[5:] for f in test_flags if f[:5] == "-Wno-"])
  return [f for f in default_flags if f not in remove] + test_flags

COPT_VARS = {
    "ABSL_GCC_FLAGS": ABSL_GCC_FLAGS,
    "ABSL_GCC_TEST_FLAGS": GccStyleFilterAndCombine(
        ABSL_GCC_FLAGS, ABSL_GCC_TEST_ADDITIONAL_FLAGS
    ),
    "ABSL_LLVM_FLAGS": ABSL_LLVM_FLAGS,
    "ABSL_LLVM_TEST_FLAGS": GccStyleFilterAndCombine(
        ABSL_LLVM_FLAGS, ABSL_LLVM_TEST_ADDITIONAL_FLAGS
    ),
    "ABSL_CLANG_CL_FLAGS": (
        MSVC_BIG_WARNING_FLAGS + MSVC_DEFINES + ABSL_LLVM_BASE_FLAGS
    ),
    "ABSL_CLANG_CL_TEST_FLAGS": (
        MSVC_BIG_WARNING_FLAGS
        + MSVC_DEFINES
        + GccStyleFilterAndCombine(
            ABSL_LLVM_BASE_FLAGS, ABSL_LLVM_TEST_ADDITIONAL_FLAGS
        )
    ),
    "ABSL_MSVC_FLAGS": (
        MSVC_BIG_WARNING_FLAGS + MSVC_WARNING_FLAGS + MSVC_DEFINES
    ),
    "ABSL_MSVC_TEST_FLAGS": (
        MSVC_BIG_WARNING_FLAGS
        + MSVC_WARNING_FLAGS
        + MSVC_DEFINES
        + [
            "/wd4018",  # signed/unsigned mismatch
            "/wd4101",  # unreferenced local variable
            "/wd4244",  # shortening conversion
            "/wd4267",  # shortening conversion
            "/wd4503",  # decorated name length exceeded, name was truncated
            "/wd4996",  # use of deprecated symbol
            "/DNOMINMAX",  # disable the min() and max() macros from <windows.h>
        ]
    ),
    "ABSL_MSVC_LINKOPTS": [
        # Object file doesn't export any previously undefined symbols
        "-ignore:4221",
    ],
}