Re: -Wall

[Liviu Ionescu <ilg@livius.net>]

> On 19 Jan 2024, at 14:55, Corinna Vinschen <vinschen@redhat.com> wrote:
> 
> ... I only found a bug because I used -Wall ...

For completeness, please note that `-Wall` does not enable **all* warnings, GCC has additional warnings, that might be useful to spot other bugs.

Below is an excerpt from my CMake scripts.

I did not check recent GCC releases, they probably include even more warnings.

Personally I'd use as many of them when `--enable-warnings`.

Regards,

Liviu


```
if("${CMAKE_C_COMPILER_VERSION}" VERSION_GREATER_EQUAL "7.0.0")

# message(VERBOSE "Adding GCC 7 warnings...")

list(APPEND ${variable_name}

# ---------------------------------------------------------------------
# Common GNU C & C++.

-Waggregate-return
-Wcast-align
-Wcast-qual
-Wconversion
-Wdouble-promotion
-Wduplicated-branches
-Wduplicated-cond
-Wextra
-Wfloat-conversion
-Wfloat-equal
-Wformat-nonliteral
-Wformat-overflow=2
-Wformat-security
-Wformat-signedness
-Wformat-truncation=2
-Wformat-y2k
-Wformat=2
-Wlogical-op
-Wmissing-declarations
# Older GCC may include non-existent SDK folders.
$<$<NOT:$<PLATFORM_ID:Darwin>>:-Wmissing-include-dirs>
-Wnull-dereference
-Wpacked
-Wpadded
-Wpointer-arith
-Wredundant-decls
-Wshadow
-Wshift-overflow=2
-Wsign-conversion
-Wswitch-default
-Wswitch-enum
-Wundef
-Wuninitialized
-Wvla

# ---------------------------------------------------------------------
# GNU C only.

$<$<COMPILE_LANGUAGE:C>:-Wbad-function-cast>
$<$<COMPILE_LANGUAGE:C>:-Wc++-compat>
$<$<COMPILE_LANGUAGE:C>:-Wduplicate-decl-specifier>
$<$<COMPILE_LANGUAGE:C>:-Wmissing-prototypes>
$<$<COMPILE_LANGUAGE:C>:-Wnested-externs>
$<$<COMPILE_LANGUAGE:C>:-Wold-style-definition>
$<$<COMPILE_LANGUAGE:C>:-Wstrict-prototypes>

# ---------------------------------------------------------------------
# GNU C++ only.

# inherits the "cxx11" ABI tag that 'std::string'
# $<$<COMPILE_LANGUAGE:CXX>:-Wabi-tag>

$<$<COMPILE_LANGUAGE:CXX>:-Wctor-dtor-privacy>
$<$<COMPILE_LANGUAGE:CXX>:-Wnoexcept>
$<$<COMPILE_LANGUAGE:CXX>:-Wnon-virtual-dtor>
$<$<COMPILE_LANGUAGE:CXX>:-Wold-style-cast>
$<$<COMPILE_LANGUAGE:CXX>:-Woverloaded-virtual>
$<$<COMPILE_LANGUAGE:CXX>:-Wplacement-new=2>
$<$<COMPILE_LANGUAGE:CXX>:-Wregister>
$<$<COMPILE_LANGUAGE:CXX>:-Wsign-promo>
$<$<COMPILE_LANGUAGE:CXX>:-Wstrict-null-sentinel>
$<$<COMPILE_LANGUAGE:CXX>:-Wsuggest-final-methods>
$<$<COMPILE_LANGUAGE:CXX>:-Wsuggest-final-types>
$<$<COMPILE_LANGUAGE:CXX>:-Wsuggest-override>
$<$<COMPILE_LANGUAGE:CXX>:-Wuseless-cast>
$<$<COMPILE_LANGUAGE:CXX>:-Wzero-as-null-pointer-constant>
)

endif()

if("${CMAKE_C_COMPILER_VERSION}" VERSION_GREATER_EQUAL "8.0.0")

# message(VERBOSE "Adding GCC 8 warnings...")

list(APPEND ${variable_name}

$<$<COMPILE_LANGUAGE:CXX>:-Wextra-semi>

)

endif()

if("${CMAKE_C_COMPILER_VERSION}" VERSION_GREATER_EQUAL "9.0.0")

# message(VERBOSE "Adding GCC 9 warnings...")

list(APPEND ${variable_name}

# None so far.
)

endif()

if("${CMAKE_C_COMPILER_VERSION}" VERSION_GREATER_EQUAL "10.0.0")

# message(VERBOSE "Adding GCC 10 warnings...")

list(APPEND ${variable_name}

# ---------------------------------------------------------------------
# Common GNU C & C++.

-Warith-conversion

# ---------------------------------------------------------------------
# GNU C++ only.

$<$<COMPILE_LANGUAGE:CXX>:-Wcomma-subscript>
$<$<COMPILE_LANGUAGE:CXX>:-Wredundant-tags>
$<$<COMPILE_LANGUAGE:CXX>:-Wvolatile>
)

# RISC-V 10.1 fails with `note: replace the class-key with 'struct'`.
if(NOT "${CMAKE_C_COMPILER_VERSION}" VERSION_EQUAL "10.1.0")

list(APPEND ${variable_name}

$<$<COMPILE_LANGUAGE:CXX>:-Wmismatched-tags>
)

endif()

endif()

elseif("${CMAKE_C_COMPILER_ID}" MATCHES ".*Clang")

message(VERBOSE "Adding clang warnings...")

list(APPEND ${variable_name}

# For clang things are much easier.
-Weverything
$<$<C_COMPILER_ID:ARMClang>:-Wno-poison-system-directories>
)

endif()
```