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Allow different cflags depending on extensions in system_libs.py #26037

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Allow different cflags depending on extensions in system_libs.py #26037

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3d268ff
Allow different cflags depending on extensions in system_libs.py
aheejin Jan 3, 2026
6cb0f46
Merge branch 'main' into cflags_file
aheejin Jan 3, 2026
5ea8134
Ruff fix
aheejin Jan 4, 2026
5d61a65
Make filename parameter mandatory
aheejin Jan 9, 2026
27c771e
Handle USE_NINJA too
aheejin Jan 9, 2026
f8364e1
Make libunwind compile with -std=c23 / -std=c++23
aheejin Jan 9, 2026
f0bae39
Merge branch 'main' into cflags_file
aheejin Jan 9, 2026
95407f0
ruff 'ARG002 Unused method argument' fix
aheejin Jan 9, 2026
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60 changes: 30 additions & 30 deletions tools/system_libs.py
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Original file line number Diff line number Diff line change
Expand Up @@ -474,7 +474,7 @@ def generate_ninja(self, build_dir, libname):
utils.safe_ensure_dirs(build_dir)
self.build_dir = build_dir

cflags = self.get_cflags()
cflags = self.get_cflags(None)
asflags = get_base_cflags(self.build_dir, preprocess=False)
input_files = self.get_files()
ninja_file = os.path.join(build_dir, 'build.ninja')
Expand All @@ -492,7 +492,6 @@ def build_objects(self, build_dir):
batches = {}
commands = []
objects = set()
cflags = self.get_cflags()
for src in self.get_files():
ext = utils.suffix(src)
if ext in {'.s', '.S', '.c'}:
Expand All @@ -506,7 +505,7 @@ def build_objects(self, build_dir):
# `-sMEMORY64`.
cmd += get_base_cflags(self.build_dir, preprocess=False)
else:
cmd += cflags
cmd += self.get_cflags(src)
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@sbc100 sbc100 Jan 8, 2026

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Since we already have the extension calculated here perhaps we can add self.cxxflags here when we have a cxx extension?

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@aheejin aheejin Jan 9, 2026

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Not sure if I understand... We don't have self.cflags either. Do you want to add both? But then why would we have both self.cflags and self.get_cflags() then?

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@sbc100 sbc100 Jan 9, 2026

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We do have self.cflags and the default self.get_cflags() will read from this field.

The idea is that for simple libraries where the cflags don't vary you can just do cflags = ['x', 'y', 'z'] at the class level.

See libunwind for example.

In this case we could just add support for cxxflags = ['x', 'y', 'z']?

cmd = self.customize_build_cmd(cmd, src)

object_basename = utils.unsuffixed_basename(src).lower()
Expand Down Expand Up @@ -586,7 +585,7 @@ def _inherit_list(cls, attr):
result += item.__dict__.get(attr, [])
return result

def get_cflags(self):
def get_cflags(self, _filename=None):
"""
Returns the list of flags to pass to emcc when building this variation
of the library.
Expand Down Expand Up @@ -710,8 +709,8 @@ def __init__(self, **kwargs):
self.is_ww = kwargs.pop('is_ww') and not self.is_mt
super().__init__(**kwargs)

def get_cflags(self):
cflags = super().get_cflags()
def get_cflags(self, _filename=None):
cflags = super().get_cflags(_filename)
if self.is_mt:
cflags += ['-pthread', '-sWASM_WORKERS']
if self.is_ww:
Expand Down Expand Up @@ -751,8 +750,8 @@ def __init__(self, **kwargs):
self.is_debug = kwargs.pop('is_debug')
super().__init__(**kwargs)

def get_cflags(self):
cflags = super().get_cflags()
def get_cflags(self, _filename=None):
cflags = super().get_cflags(_filename)
if not self.is_debug:
cflags += ['-DNDEBUG']
return cflags
Expand Down Expand Up @@ -795,8 +794,8 @@ def __init__(self, **kwargs):
self.eh_mode = kwargs.pop('eh_mode')
super().__init__(**kwargs)

def get_cflags(self):
cflags = super().get_cflags()
def get_cflags(self, _filename=None):
cflags = super().get_cflags(_filename)
match self.eh_mode:
case Exceptions.NONE:
cflags += ['-fno-exceptions']
Expand Down Expand Up @@ -850,8 +849,8 @@ def __init__(self, **kwargs):
self.eh_mode = kwargs.pop('eh_mode')
super().__init__(**kwargs)

def get_cflags(self):
cflags = super().get_cflags()
def get_cflags(self, _filename=None):
cflags = super().get_cflags(_filename)
match self.eh_mode:
case Exceptions.EMSCRIPTEN:
cflags += ['-sSUPPORT_LONGJMP=emscripten',
Expand Down Expand Up @@ -919,8 +918,8 @@ def __init__(self, **kwargs):
self.is_asan = kwargs.pop('is_asan', False)
super().__init__(**kwargs)

def get_cflags(self):
cflags = super().get_cflags()
def get_cflags(self, _filename=None):
cflags = super().get_cflags(_filename)
if self.is_asan:
cflags += ['-fsanitize=address']
return cflags
Expand Down Expand Up @@ -1478,8 +1477,8 @@ def __init__(self, **kwargs):
self.is_stub = kwargs.pop('stub')
super().__init__(**kwargs)

def get_cflags(self):
cflags = super().get_cflags()
def get_cflags(self, _filename=None):
cflags = super().get_cflags(_filename)
if self.is_debug:
cflags += ['-D_DEBUG']
# library_wasm_worker.c contains an assert that a nonnull parameter
Expand Down Expand Up @@ -1635,8 +1634,8 @@ def __init__(self, **kwargs):
# the non-debug version of libc++abi.
self.is_debug |= settings.EXCEPTION_STACK_TRACES

def get_cflags(self):
cflags = super().get_cflags()
def get_cflags(self, _filename=None):
cflags = super().get_cflags(_filename)
if not self.is_mt and not self.is_ww:
cflags.append('-D_LIBCXXABI_HAS_NO_THREADS')
match self.eh_mode:
Expand Down Expand Up @@ -1747,8 +1746,8 @@ def __init__(self, **kwargs):
def can_use(self):
return super().can_use() and self.eh_mode in (Exceptions.WASM_LEGACY, Exceptions.WASM)

def get_cflags(self):
cflags = super().get_cflags()
def get_cflags(self, _filename=None):
cflags = super().get_cflags(_filename)
cflags.append('-DNDEBUG')
if not self.is_mt and not self.is_ww:
cflags.append('-D_LIBUNWIND_HAS_NO_THREADS')
Expand All @@ -1757,6 +1756,7 @@ def get_cflags(self):
cflags.append('-D_LIBUNWIND_HAS_NO_EXCEPTIONS')
case Exceptions.EMSCRIPTEN:
cflags.append('-D__EMSCRIPTEN_EXCEPTIONS__')

return cflags


Expand Down Expand Up @@ -1789,8 +1789,8 @@ def get_files(self):
sbrk = utils.path_from_root('system/lib/libc/sbrk.c')
return [malloc, sbrk]

def get_cflags(self):
cflags = super().get_cflags()
def get_cflags(self, _filename=None):
cflags = super().get_cflags(_filename)
if self.memvalidate:
cflags += ['-DEMMALLOC_MEMVALIDATE']
if self.verbose:
Expand Down Expand Up @@ -1926,8 +1926,8 @@ def get_base_name(self):
name += '-getprocaddr'
return name

def get_cflags(self):
cflags = super().get_cflags()
def get_cflags(self, _filename=None):
cflags = super().get_cflags(_filename)
if self.is_legacy:
cflags += ['-DLEGACY_GL_EMULATION=1']
cflags += [f'-DMAX_WEBGL_VERSION={2 if self.is_webgl2 else 1}']
Expand Down Expand Up @@ -1963,8 +1963,8 @@ def __init__(self, **kwargs):
self.with_rtti = kwargs.pop('with_rtti', False)
super().__init__(**kwargs)

def get_cflags(self):
cflags = super().get_cflags()
def get_cflags(self, _filename=None):
cflags = super().get_cflags(_filename)
cflags.append('-std=c++20')
if not self.with_rtti:
cflags += ['-fno-rtti', '-DEMSCRIPTEN_HAS_UNBOUND_TYPE_NAMES=0']
Expand Down Expand Up @@ -2017,8 +2017,8 @@ def __init__(self, **kwargs):
self.ignore_case = kwargs.pop('ignore_case')
super().__init__(**kwargs)

def get_cflags(self):
cflags = super().get_cflags()
def get_cflags(self, _filename=None):
cflags = super().get_cflags(_filename)
if self.ignore_case:
cflags += ['-DWASMFS_CASE_INSENSITIVE']
return cflags
Expand Down Expand Up @@ -2204,8 +2204,8 @@ def get_base_name(self):
name += '-pure'
return name

def get_cflags(self):
cflags = super().get_cflags()
def get_cflags(self, _filename=None):
cflags = super().get_cflags(_filename)
cflags += ['-DNDEBUG', '-DEMSCRIPTEN_STANDALONE_WASM']
if self.is_mem_grow:
cflags += ['-DEMSCRIPTEN_MEMORY_GROWTH']
Expand Down