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Update bison.bzl and flex.bzl to work with Bazel 8 #2452

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Update bison.bzl and flex.bzl to work with Bazel 8 #2452

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1 change: 0 additions & 1 deletion .bazelversion
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97 changes: 84 additions & 13 deletions bazel/bison.bzl
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Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,18 @@
"""Bazel rule to run bison toolchain
"""

def _add_suffix_to_location_references(option, suffix):
"""Helper function to add a suffix to $(location ...) file names in options."""
if "$(location " in option:
# Extract the output file name
start = option.find("$(location ") + len("$(location ")
end = option.find(")", start)
file_name = option[start:end]

# Add suffix to the location reference
return option.replace("$(location " + file_name + ")", "$(location " + file_name + suffix + ")")
return option

# Adapter rule around the @rules_bison toolchain.
def genyacc(
name,
Expand All @@ -26,21 +38,80 @@ def genyacc(
extra_outs = []):
"""Build rule for generating C or C++ sources with Bison.
"""

# Note: some attributes such as (toolchains and name) cannot use select. So, although verbose, we create a
# genrule for each condition here and copy the resulting file to the expected location.

# For rules_bison toolchain case
native.genrule(
name = name + "_default",
srcs = [src],
outs = [header_out + ".default", source_out + ".default"] + [out + ".default" for out in extra_outs],
cmd = "M4=$(M4) $(BISON) --defines=$(location " + header_out + ".default) " +
"--output-file=$(location " + source_out + ".default) " +
" ".join([_add_suffix_to_location_references(opt, ".default") for opt in extra_options]) + " $<",
toolchains = [
"@rules_bison//bison:current_bison_toolchain",
"@rules_m4//m4:current_m4_toolchain",
],
tags = ["manual"],
)

# For local bison case
native.genrule(
name = name,
name = name + "_local",
srcs = [src],
outs = [header_out, source_out] + extra_outs,
cmd = select({
"//bazel:use_local_flex_bison_enabled": "bison --defines=$(location " + header_out + ") --output-file=$(location " + source_out + ") " + " ".join(extra_options) + " $<",
"@platforms//os:windows": "win_bison.exe --defines=$(location " + header_out + ") --output-file=$(location " + source_out + ") " + " ".join(extra_options) + " $<",
"//conditions:default": "M4=$(M4) $(BISON) --defines=$(location " + header_out + ") --output-file=$(location " + source_out + ") " + " ".join(extra_options) + " $<",
outs = [header_out + ".local", source_out + ".local"] + [out + ".local" for out in extra_outs],
cmd = "bison --defines=$(location " + header_out + ".local) " +
"--output-file=$(location " + source_out + ".local) " +
" ".join([_add_suffix_to_location_references(opt, ".local") for opt in extra_options]) + " $<",
tags = ["manual"],
)

# For Windows case
native.genrule(
name = name + "_windows",
srcs = [src],
outs = [header_out + ".windows", source_out + ".windows"] + [out + ".windows" for out in extra_outs],
cmd = "win_bison.exe --defines=$(location " + header_out + ".windows) " +
"--output-file=$(location " + source_out + ".windows) " +
" ".join([_add_suffix_to_location_references(opt, ".windows") for opt in extra_options]) + " $<",
tags = ["manual"],
)

# Create copy rules for each output
native.genrule(
name = name + "_copy_header",
srcs = select({
"//bazel:use_local_flex_bison_enabled": [header_out + ".local"],
"@platforms//os:windows": [header_out + ".windows"],
"//conditions:default": [header_out + ".default"],
}),
toolchains = select({
"//bazel:use_local_flex_bison_enabled": [],
"@platforms//os:windows": [],
"//conditions:default": [
"@rules_bison//bison:current_bison_toolchain",
"@rules_m4//m4:current_m4_toolchain",
],
outs = [header_out],
cmd = "cp $< $@",
)

native.genrule(
name = name + "_copy_source",
srcs = select({
"//bazel:use_local_flex_bison_enabled": [source_out + ".local"],
"@platforms//os:windows": [source_out + ".windows"],
"//conditions:default": [source_out + ".default"],
}),
outs = [source_out],
cmd = "cp $< $@",
)

# Create copy rules for each extra output
for extra_out in extra_outs:
sanitized_name = extra_out.replace(".", "_").replace("/", "_").replace("-", "_")
native.genrule(
name = name + "_copy_" + sanitized_name,
srcs = select({
"//bazel:use_local_flex_bison_enabled": [extra_out + ".local"],
"@platforms//os:windows": [extra_out + ".windows"],
"//conditions:default": [extra_out + ".default"],
}),
outs = [extra_out],
cmd = "cp $< $@",
)
56 changes: 42 additions & 14 deletions bazel/flex.bzl
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Original file line number Diff line number Diff line change
Expand Up @@ -20,21 +20,49 @@
def genlex(name, src, out):
"""Generate C/C++ language source from lex file using Flex
"""

# Note: some attributes such as (toolchains and name) cannot use select. So, although verbose, we create a
# genrule for each condition here and copy the resulting file to the expected location.

# For rules_flex default case
native.genrule(
name = name,
name = name + "_default",
srcs = [src],
outs = [out],
cmd = select({
"//bazel:use_local_flex_bison_enabled": "flex --outfile=$@ $<",
"@platforms//os:windows": "win_flex.exe --outfile=$@ $<",
"//conditions:default": "M4=$(M4) $(FLEX) --outfile=$@ $<",
}),
toolchains = select({
"//bazel:use_local_flex_bison_enabled": [],
"@platforms//os:windows": [],
"//conditions:default": [
"@rules_flex//flex:current_flex_toolchain",
"@rules_m4//m4:current_m4_toolchain",
],
outs = [out + ".default"],
cmd = "M4=$(M4) $(FLEX) --outfile=$(location " + out + ".default) $<",
toolchains = [
"@rules_flex//flex:current_flex_toolchain",
"@rules_m4//m4:current_m4_toolchain",
],
tags = ["manual"],
)

# For local flex case
native.genrule(
name = name + "_local",
srcs = [src],
outs = [out + ".local"],
cmd = "flex --outfile=$(location " + out + ".local) $<",
tags = ["manual"],
)

# For Windows case
native.genrule(
name = name + "_windows",
srcs = [src],
outs = [out + ".windows"],
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@hzeller hzeller Aug 29, 2025

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ah, the suffix is not mysterious anymore. But looks like it messes with the rest of the build-system

cmd = "win_flex.exe --outfile=$(location " + out + ".windows) $<",
tags = ["manual"],
)

# Create a copy rule to get the final output
native.genrule(
name = name,
srcs = select({
"//bazel:use_local_flex_bison_enabled": [out + ".local"],
"@platforms//os:windows": [out + ".windows"],
"//conditions:default": [out + ".default"],
}),
outs = [out],
cmd = "cp $< $@",
)
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