path: root/build/moz.configure/warnings.configure

# -*- Mode: python; c-basic-offset: 4; indent-tabs-mode: nil; tab-width: 40 -*-
# vim: set filetype=python:
# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.

option(
    "--enable-warnings-as-errors",
    env="MOZ_ENABLE_WARNINGS_AS_ERRORS",
    default=depends("MOZ_AUTOMATION")(lambda x: bool(x)),
    help="{Enable|Disable} treating warnings as errors",
)


@depends("--enable-warnings-as-errors")
def rust_warning_flags(warnings_as_errors):
    flags = []

    # Note that cargo passes --cap-lints warn to rustc for third-party code, so
    # we don't need a very complicated setup.
    if warnings_as_errors:
        flags.append("-Dwarnings")
    else:
        flags.extend(("--cap-lints", "warn"))

    return flags


c_warning_flag = dependable("-Werror")


@depends("--enable-warnings-as-errors", c_warning_flag)
def warnings_as_errors(warnings_as_errors, c_warning_flag):
    if not warnings_as_errors:
        return ""

    return c_warning_flag


set_config("WARNINGS_AS_ERRORS", warnings_as_errors)
# We have a peculiar setup in old-configure.in where some compilation tests
# depend on enabling warnings-as-errors even if it's disabled for Firefox
# compilation.  We therefore need this assignment.
add_old_configure_assignment("WARNINGS_AS_ERRORS", c_warning_flag)


# GCC/Clang warnings:
# https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html
# https://clang.llvm.org/docs/DiagnosticsReference.html

# lots of useful warnings
add_gcc_warning("-Wall")

# catch implicit truncation of enum values assigned to smaller bit fields
check_and_add_gcc_warning("-Wbitfield-enum-conversion")

# catches bugs, e.g. "if (c); foo();", few false positives
add_gcc_warning("-Wempty-body")

# catches return types with qualifiers like const
add_gcc_warning("-Wignored-qualifiers")

# function declaration hides virtual function from base class.
# Don't enable for GCC, since it's more strict than clang,
# and the additional cases it covers are not valuable.
add_gcc_warning(
    "-Woverloaded-virtual",
    cxx_compiler,
    when=depends(cxx_compiler)(lambda c: c.type != "gcc"),
)

# catches pointer arithmetic using NULL or sizeof(void)
add_gcc_warning("-Wpointer-arith")

# catch modifying constructor parameter that shadows member variable
check_and_add_gcc_warning("-Wshadow-field-in-constructor-modified")

# catches comparing signed/unsigned ints
add_gcc_warning("-Wsign-compare")

# catches overflow bugs, few false positives
add_gcc_warning("-Wtype-limits")

# catches some dead code
add_gcc_warning("-Wunreachable-code")
check_and_add_gcc_warning("-Wunreachable-code-return")

# catches treating string literals as non-const
add_gcc_warning("-Wwrite-strings", cxx_compiler)

# turned on by -Wall, but we use offsetof on non-POD types frequently
add_gcc_warning("-Wno-invalid-offsetof", cxx_compiler)

# catches objects passed by value to variadic functions.
check_and_add_gcc_warning("-Wclass-varargs")

# catches empty if/switch/for initialization statements that have no effect
check_and_add_gcc_warning("-Wempty-init-stmt", cxx_compiler)

# catches some implicit conversion of floats to ints
check_and_add_gcc_warning("-Wfloat-overflow-conversion")
check_and_add_gcc_warning("-Wfloat-zero-conversion")

# catches issues around loops
check_and_add_gcc_warning("-Wloop-analysis")
# But, disable range-loop-analysis because it can raise unhelpful false
# positives.
check_and_add_gcc_warning("-Wno-range-loop-analysis")

# catches C++ version forward-compat issues
check_and_add_gcc_warning("-Wc++2a-compat", cxx_compiler)

# catches possible misuse of the comma operator
check_and_add_gcc_warning("-Wcomma", cxx_compiler)

# catches duplicated conditions in if-else-if chains
check_and_add_gcc_warning("-Wduplicated-cond")

# catches unintentional switch case fallthroughs
check_and_add_gcc_warning("-Wimplicit-fallthrough", cxx_compiler)

# catches unused variable/function declarations
check_and_add_gcc_warning("-Wunused-function", cxx_compiler)
check_and_add_gcc_warning("-Wunused-variable", cxx_compiler)

# catches expressions used as a null pointer constant
# XXX: at the time of writing, the version of clang used on the OS X test
# machines has a bug that causes it to reject some valid files if both
# -Wnon-literal-null-conversion and -Wsometimes-uninitialized are
# specified. We work around this by instead using
# -Werror=non-literal-null-conversion, but we only do that when
# --enable-warnings-as-errors is specified so that no unexpected fatal
# warnings are produced.
check_and_add_gcc_warning(
    "-Werror=non-literal-null-conversion", when="--enable-warnings-as-errors"
)

# catches string literals used in boolean expressions
check_and_add_gcc_warning("-Wstring-conversion")

# catches comparisons that are always true or false
check_and_add_gcc_warning("-Wtautological-overlap-compare")
check_and_add_gcc_warning("-Wtautological-unsigned-enum-zero-compare")
check_and_add_gcc_warning("-Wtautological-unsigned-zero-compare")
# This can be triggered by certain patterns used deliberately in portable code
check_and_add_gcc_warning("-Wno-error=tautological-type-limit-compare")

# we inline 'new' and 'delete' in mozalloc
check_and_add_gcc_warning("-Wno-inline-new-delete", cxx_compiler)

# Prevent the following GCC warnings from being treated as errors:
# too many false positives
check_and_add_gcc_warning("-Wno-error=maybe-uninitialized")

# we don't want our builds held hostage when a platform-specific API
# becomes deprecated.
check_and_add_gcc_warning("-Wno-error=deprecated-declarations")

# false positives depending on optimization
check_and_add_gcc_warning("-Wno-error=array-bounds")

# can't get rid of those PGO warnings
check_and_add_gcc_warning("-Wno-error=coverage-mismatch")

# -Wbackend-plugin warnings from Android PGO profile-use builds:
# error: /builds/worker/workspace/build/src/mozglue/misc/AutoProfilerLabel.cpp:
#  Function control flow change detected (hash mismatch)
#  _ZN7mozilla17AutoProfilerLabelD2Ev [-Werror,-Wbackend-plugin]
check_and_add_gcc_warning("-Wno-error=backend-plugin")

# false positives depending on optimizations
check_and_add_gcc_warning("-Wno-error=free-nonheap-object")

# Would be a pain to fix all occurrences, for very little gain
check_and_add_gcc_warning("-Wno-multistatement-macros")

# Disable the -Werror for return-std-move because of a false positive
# on nsTAutoStringN: https://bugs.llvm.org/show_bug.cgi?id=37249
check_and_add_gcc_warning("-Wno-error=return-std-move")

# Disable the -Werror for -Wclass-memaccess as we have a long
# tail of issues to fix
check_and_add_gcc_warning("-Wno-error=class-memaccess")

# -Watomic-alignment is a new warning in clang 7 that seems way too broad.
# https://bugs.llvm.org/show_bug.cgi?id=38593
check_and_add_gcc_warning("-Wno-error=atomic-alignment")

# New warning with gcc 9. Not useful
# https://bugzilla.mozilla.org/show_bug.cgi?id=1515356
check_and_add_gcc_warning("-Wno-error=deprecated-copy")

# catches format/argument mismatches with printf
c_format_warning, cxx_format_warning = check_and_add_gcc_warning(
    "-Wformat", when=depends(target)(lambda t: t.kernel != "WINNT")
)

# Add compile-time warnings for unprotected functions and format functions
# that represent possible security problems. Enable this only when -Wformat
# is enabled, otherwise it is an error
check_and_add_gcc_warning(
    "-Wformat-security", when=c_format_warning & cxx_format_warning
)
check_and_add_gcc_warning(
    "-Wformat-overflow=2", when=c_format_warning & cxx_format_warning
)

# Other MinGW specific things
with only_when(depends(target)(lambda t: t.kernel == "WINNT")):
    # When compiling for Windows with gcc, we encounter lots of "#pragma warning"'s
    # which is an MSVC-only pragma that GCC does not recognize.
    check_and_add_gcc_warning("-Wno-unknown-pragmas")

    # When compiling for Windows with gcc, gcc throws false positives and true
    # positives where the callsite is ifdef-ed out
    check_and_add_gcc_warning("-Wno-unused-function")

    # When compiling for Windows with gcc, gcc cannot produce this warning
    # correctly: it mistakes DWORD_PTR and ULONG_PTR as types you cannot
    # give NULL to. (You can in fact do that.)
    check_and_add_gcc_warning("-Wno-conversion-null")

    # Throughout the codebase we regularly have switch statements off of enums
    # without covering every value in the enum. We don't care about these warnings.
    check_and_add_gcc_warning("-Wno-switch")

    # Another code pattern we have is using start and end constants in enums of
    # different types. We do this for safety, but then when comparing it throws
    # an error, which we would like to ignore. This seems to only affect the MinGW
    # build, but we're not sure why.
    check_and_add_gcc_warning("-Wno-enum-compare")

# We hit this all over the place with the gtest INSTANTIATE_TEST_CASE_P macro
check_and_add_gcc_warning("-Wno-gnu-zero-variadic-macro-arguments")

# Make it an error to be missing function declarations for C code.
check_and_add_gcc_warning("-Werror=implicit-function-declaration", c_compiler)

# New in clang 11. We can't really do anything about this warning.
check_and_add_gcc_warning("-Wno-psabi")

# Disable broken missing-braces warning on old clang versions
check_and_add_gcc_warning(
    "-Wno-missing-braces",
    when=depends(c_compiler)(lambda c: c.type == "clang" and c.version < "6.0"),
)


# Please keep these last in this file
add_old_configure_assignment("_WARNINGS_CFLAGS", warnings_flags.cflags)
add_old_configure_assignment("_WARNINGS_CXXFLAGS", warnings_flags.cxxflags)
add_old_configure_assignment("_WARNINGS_HOST_CFLAGS", warnings_flags.host_cflags)
add_old_configure_assignment("_WARNINGS_HOST_CXXFLAGS", warnings_flags.host_cxxflags)