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Merged
linzhp merged 1 commit into from
Jan 26, 2026
+82 −12
Merged

Add extra_{exec,target}_compatible_with extensions #240

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4 changes: 4 additions & 0 deletions toolchain/defs.bzl
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Original file line number Diff line number Diff line change
Expand Up @@ -66,6 +66,8 @@ def toolchains(
host_platform_sha256 = HOST_PLATFORM_SHA256,
host_platform_ext = _HOST_PLATFORM_EXT,
exec_platforms = {},
extra_exec_compatible_with = [],
extra_target_compatible_with = [],
extra_target_settings = []):
"""
Download zig toolchain and declare bazel toolchains.
Expand All @@ -86,6 +88,8 @@ def toolchains(
zig_sdk_repository(
name = "zig_sdk",
exec_platforms = exec_platforms,
extra_exec_compatible_with = extra_exec_compatible_with,
extra_target_compatible_with = extra_target_compatible_with,
extra_target_settings = extra_target_settings,
)

Expand Down
31 changes: 30 additions & 1 deletion toolchain/ext.bzl
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Expand Up @@ -22,11 +22,27 @@ _extra_target_settings = tag_class(
doc = "Each setting is added to every toolchain to make them more restrictive",
)

_extra_target_compatible_with = tag_class(
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@linzhp linzhp Jan 25, 2026

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with these two new tag classes, do you think we still need _extra_target_settings?

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@ddunl ddunl Jan 25, 2026

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I don't feel strongly either way, for the project that motivated me to send this PR I definitely won't need it now that I can specify with target_compatible_with, but I could imagine situations where it might be convenient to control which toolchain is used with settings rather than constraints.

attrs = {
"constraints": attr.label_list(),
},
doc = "Extra constraints added to every toolchain's `target_compatible_with`",
)

_extra_exec_compatible_with = tag_class(
attrs = {
"constraints": attr.label_list(),
},
doc = "Extra constraints added to every toolchain's `exec_compatible_with`",
)

def _toolchains_impl(mctx):
exec_platforms = {}
root_direct_deps = []
root_direct_dev_deps = []
is_non_dev_dependency = mctx.root_module_has_non_dev_dependency
extra_exec_compatible_with = []
extra_target_compatible_with = []
extra_target_settings = []

for mod in mctx.modules:
Expand All @@ -40,7 +56,18 @@ def _toolchains_impl(mctx):
for tag in mod.tags.extra_target_settings:
extra_target_settings += tag.settings

repos = zig_toolchains(exec_platforms = exec_platforms, extra_target_settings = extra_target_settings)
for tag in mod.tags.extra_exec_compatible_with:
extra_exec_compatible_with += tag.constraints

for tag in mod.tags.extra_target_compatible_with:
extra_target_compatible_with += tag.constraints

repos = zig_toolchains(
exec_platforms = exec_platforms,
extra_exec_compatible_with = extra_exec_compatible_with,
extra_target_compatible_with = extra_target_compatible_with,
extra_target_settings = extra_target_settings,
)

root_direct_deps = list(repos.public) if is_non_dev_dependency else []
root_direct_dev_deps = list(repos.public) if not is_non_dev_dependency else []
Expand All @@ -59,6 +86,8 @@ toolchains = module_extension(
implementation = _toolchains_impl,
tag_classes = {
"exec_platform": _exec_platform,
"extra_exec_compatible_with": _extra_exec_compatible_with,
"extra_target_compatible_with": _extra_target_compatible_with,
"extra_target_settings": _extra_target_settings,
},
)
7 changes: 6 additions & 1 deletion toolchain/libc_aware/toolchain/BUILD.bazel.tmpl
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Original file line number Diff line number Diff line change
Expand Up @@ -7,4 +7,9 @@ package(
default_visibility = ["//visibility:public"],
)

declare_libc_aware_toolchains(configs = {configs}, extra_target_settings = {extra_target_settings})
declare_libc_aware_toolchains(
configs = {configs},
extra_exec_compatible_with = {extra_exec_compatible_with},
extra_target_compatible_with = {extra_target_compatible_with},
extra_target_settings = {extra_target_settings},
)
12 changes: 12 additions & 0 deletions toolchain/private/repositories.bzl
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,8 @@ load("@hermetic_cc_toolchain//toolchain:utils.bzl", "quote")
load("@hermetic_cc_toolchain//toolchain/private:defs.bzl", "transform_arch_name", "transform_os_name")

def _define_zig_toolchains(repository_ctx, configs, package = ""):
extra_exec_compatible_with = "[" + " ".join([quote(str(setting)) + "," for setting in repository_ctx.attr.extra_exec_compatible_with]) + "]"
extra_target_compatible_with = "[" + " ".join([quote(str(setting)) + "," for setting in repository_ctx.attr.extra_target_compatible_with]) + "]"
extra_target_settings = "[" + " ".join([quote(str(setting)) + "," for setting in repository_ctx.attr.extra_target_settings]) + "]"

repository_ctx.template(
Expand All @@ -10,6 +12,8 @@ def _define_zig_toolchains(repository_ctx, configs, package = ""):
executable = False,
substitutions = {
"{configs}": repr(configs),
"{extra_exec_compatible_with}": extra_exec_compatible_with,
"{extra_target_compatible_with}": extra_target_compatible_with,
"{extra_target_settings}": extra_target_settings,
},
)
Expand All @@ -20,6 +24,8 @@ def _define_zig_toolchains(repository_ctx, configs, package = ""):
executable = False,
substitutions = {
"{configs}": repr(configs),
"{extra_exec_compatible_with}": extra_exec_compatible_with,
"{extra_target_compatible_with}": extra_target_compatible_with,
"{extra_target_settings}": extra_target_settings,
},
)
Expand Down Expand Up @@ -96,6 +102,12 @@ zig_sdk_repository = repository_rule(
doc = "Dictionary, where the keys are oses and the values are lists of supported architectures",
mandatory = True,
),
"extra_exec_compatible_with": attr.label_list(
doc = "Additional constraints added to the `exec_compatible_with` attribute of each generated toolchain",
),
"extra_target_compatible_with": attr.label_list(
doc = "Additional constraints added to the `target_compatible_with` attribute of each generated toolchain",
),
"extra_target_settings": attr.label_list(
doc = "Additional settings to add to the generated toolchains, to make them more restrictive",
),
Expand Down
7 changes: 6 additions & 1 deletion toolchain/toolchain/BUILD.bazel.tmpl
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Original file line number Diff line number Diff line change
Expand Up @@ -4,4 +4,9 @@ package(
default_visibility = ["//visibility:public"],
)

declare_toolchains(configs = {configs}, extra_target_settings = {extra_target_settings})
declare_toolchains(
configs = {configs},
extra_exec_compatible_with = {extra_exec_compatible_with},
extra_target_compatible_with = {extra_target_compatible_with},
extra_target_settings = {extra_target_settings},
)
33 changes: 24 additions & 9 deletions toolchain/toolchain/defs.bzl
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Original file line number Diff line number Diff line change
@@ -1,6 +1,10 @@
load("@hermetic_cc_toolchain//toolchain/private:defs.bzl", "target_structs")

def declare_toolchains(configs = "", extra_target_settings = []):
def declare_toolchains(
configs = "",
extra_exec_compatible_with = [],
extra_target_compatible_with = [],
extra_target_settings = []):
for target_config in target_structs():
gotarget = target_config.gotarget
zigtarget = target_config.zigtarget
Expand All @@ -12,11 +16,15 @@ def declare_toolchains(configs = "", extra_target_settings = []):
if hasattr(target_config, "libc_constraint"):
extra_constraints = ["@zig_sdk//libc:unconstrained"]

_declare_toolchain(gotarget, zigtarget, target_config.constraint_values + extra_constraints, configs, extra_target_settings)
_declare_toolchain(gotarget, zigtarget, target_config.constraint_values + extra_constraints, configs, extra_exec_compatible_with, extra_target_compatible_with, extra_target_settings)

_declare_zig_toolchain("zig", configs)

def declare_libc_aware_toolchains(configs = "", extra_target_settings = []):
def declare_libc_aware_toolchains(
configs = "",
extra_exec_compatible_with = [],
extra_target_compatible_with = [],
extra_target_settings = []):
for target_config in target_structs():
gotarget = target_config.gotarget
zigtarget = target_config.zigtarget
Expand All @@ -25,15 +33,22 @@ def declare_libc_aware_toolchains(configs = "", extra_target_settings = []):
# is only selected if libc is not expicitly set and another one that is
# only selected if the specific libc variant is selected.
if hasattr(target_config, "libc_constraint"):
_declare_toolchain(gotarget, zigtarget, target_config.constraint_values + [target_config.libc_constraint], configs, extra_target_settings)
_declare_toolchain(gotarget, zigtarget, target_config.constraint_values + [target_config.libc_constraint], configs, extra_exec_compatible_with, extra_target_compatible_with, extra_target_settings)

def _declare_toolchain(gotarget, zigtarget, target_compatible_with, configs, extra_target_settings):
def _declare_toolchain(
gotarget,
zigtarget,
target_compatible_with,
configs,
extra_exec_compatible_with,
extra_target_compatible_with,
extra_target_settings):
# register two kinds of toolchain targets: Go and Zig conventions.
# Go convention: amd64/arm64, linux/darwin
native.toolchain(
name = gotarget,
exec_compatible_with = ["{}//:exec_os".format(configs), "{}//:exec_cpu".format(configs)],
target_compatible_with = target_compatible_with,
exec_compatible_with = ["{}//:exec_os".format(configs), "{}//:exec_cpu".format(configs)] + extra_exec_compatible_with,
target_compatible_with = target_compatible_with + extra_target_compatible_with,
target_settings = extra_target_settings,
toolchain = "{}//:{}_cc".format(configs, zigtarget),
toolchain_type = "@bazel_tools//tools/cpp:toolchain_type",
Expand All @@ -42,8 +57,8 @@ def _declare_toolchain(gotarget, zigtarget, target_compatible_with, configs, ext
# Zig convention: x86_64/aarch64, linux/macos
native.toolchain(
name = zigtarget,
exec_compatible_with = ["{}//:exec_os".format(configs), "{}//:exec_cpu".format(configs)],
target_compatible_with = target_compatible_with,
exec_compatible_with = ["{}//:exec_os".format(configs), "{}//:exec_cpu".format(configs)] + extra_exec_compatible_with,
target_compatible_with = target_compatible_with + extra_target_compatible_with,
target_settings = extra_target_settings,
toolchain = "{}//:{}_cc".format(configs, zigtarget),
toolchain_type = "@bazel_tools//tools/cpp:toolchain_type",
Expand Down