xref: /aosp_15_r20/external/bazelbuild-rules_rust/rust/toolchain.bzl (revision d4726bddaa87cc4778e7472feed243fa4b6c267f)
1"""The rust_toolchain rule definition and implementation."""
2
3load("@bazel_skylib//rules:common_settings.bzl", "BuildSettingInfo")
4load("//rust/platform:triple.bzl", "triple")
5load("//rust/private:common.bzl", "rust_common")
6load("//rust/private:rust_analyzer.bzl", _rust_analyzer_toolchain = "rust_analyzer_toolchain")
7load(
8    "//rust/private:rustfmt.bzl",
9    _current_rustfmt_toolchain = "current_rustfmt_toolchain",
10    _rustfmt_toolchain = "rustfmt_toolchain",
11)
12load(
13    "//rust/private:utils.bzl",
14    "dedent",
15    "dedup_expand_location",
16    "find_cc_toolchain",
17    "is_exec_configuration",
18    "is_std_dylib",
19    "make_static_lib_symlink",
20)
21load("//rust/settings:incompatible.bzl", "IncompatibleFlagInfo")
22
23rust_analyzer_toolchain = _rust_analyzer_toolchain
24rustfmt_toolchain = _rustfmt_toolchain
25current_rustfmt_toolchain = _current_rustfmt_toolchain
26
27def _rust_stdlib_filegroup_impl(ctx):
28    rust_std = ctx.files.srcs
29    dot_a_files = []
30    between_alloc_and_core_files = []
31    core_files = []
32    between_core_and_std_files = []
33    std_files = []
34    test_files = []
35    memchr_files = []
36    alloc_files = []
37    self_contained_files = [
38        file
39        for file in rust_std
40        if file.basename.endswith(".o") and "self-contained" in file.path
41    ]
42    panic_files = []
43
44    std_rlibs = [f for f in rust_std if f.basename.endswith(".rlib")]
45    if std_rlibs:
46        # test depends on std
47        # std depends on everything except test
48        #
49        # core only depends on alloc, but we poke adler in there
50        # because that needs to be before miniz_oxide
51        #
52        # panic_unwind depends on unwind, alloc, cfg_if, compiler_builtins, core, libc
53        # panic_abort depends on alloc, cfg_if, compiler_builtins, core, libc
54        #
55        # alloc depends on the allocator_library if it's configured, but we
56        # do that later.
57        dot_a_files = [make_static_lib_symlink(ctx.label.package, ctx.actions, f) for f in std_rlibs]
58
59        alloc_files = [f for f in dot_a_files if "alloc" in f.basename and "std" not in f.basename]
60        between_alloc_and_core_files = [f for f in dot_a_files if "compiler_builtins" in f.basename]
61        core_files = [f for f in dot_a_files if ("core" in f.basename or "adler" in f.basename) and "std" not in f.basename]
62        panic_files = [f for f in dot_a_files if f.basename in ["cfg_if", "libc", "panic_abort", "panic_unwind", "unwind"]]
63        between_core_and_std_files = [
64            f
65            for f in dot_a_files
66            if "alloc" not in f.basename and "compiler_builtins" not in f.basename and "core" not in f.basename and "adler" not in f.basename and "std" not in f.basename and "memchr" not in f.basename and "test" not in f.basename
67        ]
68        memchr_files = [f for f in dot_a_files if "memchr" in f.basename]
69        std_files = [f for f in dot_a_files if "std" in f.basename]
70        test_files = [f for f in dot_a_files if "test" in f.basename]
71
72        partitioned_files_len = len(alloc_files) + len(between_alloc_and_core_files) + len(core_files) + len(between_core_and_std_files) + len(memchr_files) + len(std_files) + len(test_files)
73        if partitioned_files_len != len(dot_a_files):
74            partitioned = alloc_files + between_alloc_and_core_files + core_files + between_core_and_std_files + memchr_files + std_files + test_files
75            for f in sorted(partitioned):
76                # buildifier: disable=print
77                print("File partitioned: {}".format(f.basename))
78            fail("rust_toolchain couldn't properly partition rlibs in rust_std. Partitioned {} out of {} files. This is probably a bug in the rule implementation.".format(partitioned_files_len, len(dot_a_files)))
79
80    std_dylib = None
81
82    for file in rust_std:
83        if is_std_dylib(file):
84            std_dylib = file
85            break
86
87    return [
88        DefaultInfo(
89            files = depset(ctx.files.srcs),
90            runfiles = ctx.runfiles(ctx.files.srcs),
91        ),
92        rust_common.stdlib_info(
93            std_rlibs = std_rlibs,
94            dot_a_files = dot_a_files,
95            between_alloc_and_core_files = between_alloc_and_core_files,
96            core_files = core_files,
97            between_core_and_std_files = between_core_and_std_files,
98            std_files = std_files,
99            std_dylib = std_dylib,
100            test_files = test_files,
101            memchr_files = memchr_files,
102            alloc_files = alloc_files,
103            self_contained_files = self_contained_files,
104            panic_files = panic_files,
105            srcs = ctx.attr.srcs,
106        ),
107    ]
108
109rust_stdlib_filegroup = rule(
110    doc = "A dedicated filegroup-like rule for Rust stdlib artifacts.",
111    implementation = _rust_stdlib_filegroup_impl,
112    attrs = {
113        "srcs": attr.label_list(
114            allow_files = True,
115            doc = "The list of targets/files that are components of the rust-stdlib file group",
116            mandatory = True,
117        ),
118    },
119)
120
121def _ltl(library, ctx, cc_toolchain, feature_configuration):
122    """A helper to generate `LibraryToLink` objects
123
124    Args:
125        library (File): A rust library file to link.
126        ctx (ctx): The rule's context object.
127        cc_toolchain (CcToolchainInfo): A cc toolchain provider to be used.
128        feature_configuration (feature_configuration): feature_configuration to be queried.
129
130    Returns:
131        LibraryToLink: A provider containing information about libraries to link.
132    """
133    return cc_common.create_library_to_link(
134        actions = ctx.actions,
135        feature_configuration = feature_configuration,
136        cc_toolchain = cc_toolchain,
137        static_library = library,
138        pic_static_library = library,
139    )
140
141def _make_libstd_and_allocator_ccinfo(ctx, rust_std, allocator_library, std = "std"):
142    """Make the CcInfo (if possible) for libstd and allocator libraries.
143
144    Args:
145        ctx (ctx): The rule's context object.
146        rust_std: The Rust standard library.
147        allocator_library: The target to use for providing allocator functions.
148        std: Standard library flavor. Currently only "std" and "no_std_with_alloc" are supported,
149             accompanied with the default panic behavior.
150
151
152    Returns:
153        A CcInfo object for the required libraries, or None if no such libraries are available.
154    """
155    cc_toolchain, feature_configuration = find_cc_toolchain(ctx)
156    cc_infos = []
157
158    if not rust_common.stdlib_info in rust_std:
159        fail(dedent("""\
160            {} --
161            The `rust_lib` ({}) must be a target providing `rust_common.stdlib_info`
162            (typically `rust_stdlib_filegroup` rule from @rules_rust//rust:defs.bzl).
163            See https://github.com/bazelbuild/rules_rust/pull/802 for more information.
164        """).format(ctx.label, rust_std))
165    rust_stdlib_info = rust_std[rust_common.stdlib_info]
166
167    if rust_stdlib_info.self_contained_files:
168        compilation_outputs = cc_common.create_compilation_outputs(
169            objects = depset(rust_stdlib_info.self_contained_files),
170        )
171
172        linking_context, _linking_outputs = cc_common.create_linking_context_from_compilation_outputs(
173            name = ctx.label.name,
174            actions = ctx.actions,
175            feature_configuration = feature_configuration,
176            cc_toolchain = cc_toolchain,
177            compilation_outputs = compilation_outputs,
178        )
179
180        cc_infos.append(CcInfo(
181            linking_context = linking_context,
182        ))
183
184    if rust_stdlib_info.std_rlibs:
185        alloc_inputs = depset(
186            [_ltl(f, ctx, cc_toolchain, feature_configuration) for f in rust_stdlib_info.alloc_files],
187        )
188        between_alloc_and_core_inputs = depset(
189            [_ltl(f, ctx, cc_toolchain, feature_configuration) for f in rust_stdlib_info.between_alloc_and_core_files],
190            transitive = [alloc_inputs],
191            order = "topological",
192        )
193        core_inputs = depset(
194            [_ltl(f, ctx, cc_toolchain, feature_configuration) for f in rust_stdlib_info.core_files],
195            transitive = [between_alloc_and_core_inputs],
196            order = "topological",
197        )
198
199        # The libraries panic_abort and panic_unwind are alternatives.
200        # The std by default requires panic_unwind.
201        # Exclude panic_abort if panic_unwind is present.
202        # TODO: Provide a setting to choose between panic_abort and panic_unwind.
203        filtered_between_core_and_std_files = rust_stdlib_info.between_core_and_std_files
204        has_panic_unwind = [
205            f
206            for f in filtered_between_core_and_std_files
207            if "panic_unwind" in f.basename
208        ]
209        if has_panic_unwind:
210            filtered_between_core_and_std_files = [
211                f
212                for f in filtered_between_core_and_std_files
213                if "abort" not in f.basename
214            ]
215            core_alloc_and_panic_inputs = depset(
216                [
217                    _ltl(f, ctx, cc_toolchain, feature_configuration)
218                    for f in rust_stdlib_info.panic_files
219                    if "unwind" not in f.basename
220                ],
221                transitive = [core_inputs],
222                order = "topological",
223            )
224        else:
225            core_alloc_and_panic_inputs = depset(
226                [
227                    _ltl(f, ctx, cc_toolchain, feature_configuration)
228                    for f in rust_stdlib_info.panic_files
229                    if "unwind" not in f.basename
230                ],
231                transitive = [core_inputs],
232                order = "topological",
233            )
234        memchr_inputs = depset(
235            [
236                _ltl(f, ctx, cc_toolchain, feature_configuration)
237                for f in rust_stdlib_info.memchr_files
238            ],
239            transitive = [core_inputs],
240            order = "topological",
241        )
242        between_core_and_std_inputs = depset(
243            [
244                _ltl(f, ctx, cc_toolchain, feature_configuration)
245                for f in filtered_between_core_and_std_files
246            ],
247            transitive = [memchr_inputs],
248            order = "topological",
249        )
250
251        if _experimental_link_std_dylib(ctx):
252            # std dylib has everything so that we do not need to include all std_files
253            std_inputs = depset(
254                [cc_common.create_library_to_link(
255                    actions = ctx.actions,
256                    feature_configuration = feature_configuration,
257                    cc_toolchain = cc_toolchain,
258                    dynamic_library = rust_stdlib_info.std_dylib,
259                )],
260            )
261        else:
262            std_inputs = depset(
263                [
264                    _ltl(f, ctx, cc_toolchain, feature_configuration)
265                    for f in rust_stdlib_info.std_files
266                ],
267                transitive = [between_core_and_std_inputs],
268                order = "topological",
269            )
270
271        test_inputs = depset(
272            [
273                _ltl(f, ctx, cc_toolchain, feature_configuration)
274                for f in rust_stdlib_info.test_files
275            ],
276            transitive = [std_inputs],
277            order = "topological",
278        )
279
280        if std == "std":
281            link_inputs = cc_common.create_linker_input(
282                owner = rust_std.label,
283                libraries = test_inputs,
284            )
285        elif std == "no_std_with_alloc":
286            link_inputs = cc_common.create_linker_input(
287                owner = rust_std.label,
288                libraries = core_alloc_and_panic_inputs,
289            )
290        else:
291            fail("Requested '{}' std mode is currently not supported.".format(std))
292
293        allocator_inputs = None
294        if allocator_library:
295            allocator_inputs = [allocator_library[CcInfo].linking_context.linker_inputs]
296
297        cc_infos.append(CcInfo(
298            linking_context = cc_common.create_linking_context(
299                linker_inputs = depset(
300                    [link_inputs],
301                    transitive = allocator_inputs,
302                    order = "topological",
303                ),
304            ),
305        ))
306
307    if cc_infos:
308        return cc_common.merge_cc_infos(
309            direct_cc_infos = cc_infos,
310        )
311    return None
312
313def _symlink_sysroot_tree(ctx, name, target):
314    """Generate a set of symlinks to files from another target
315
316    Args:
317        ctx (ctx): The toolchain's context object
318        name (str): The name of the sysroot directory (typically `ctx.label.name`)
319        target (Target): A target owning files to symlink
320
321    Returns:
322        depset[File]: A depset of the generated symlink files
323    """
324    tree_files = []
325    for file in target.files.to_list():
326        # Parse the path to the file relative to the workspace root so a
327        # symlink matching this path can be created within the sysroot.
328
329        # The code blow attempts to parse any workspace names out of the
330        # path. For local targets, this code is a noop.
331        if target.label.workspace_root:
332            file_path = file.path.split(target.label.workspace_root, 1)[-1]
333        else:
334            file_path = file.path
335
336        symlink = ctx.actions.declare_file("{}/{}".format(name, file_path.lstrip("/")))
337
338        ctx.actions.symlink(
339            output = symlink,
340            target_file = file,
341        )
342
343        tree_files.append(symlink)
344
345    return depset(tree_files)
346
347def _symlink_sysroot_bin(ctx, name, directory, target):
348    """Crete a symlink to a target file.
349
350    Args:
351        ctx (ctx): The rule's context object
352        name (str): A common name for the output directory
353        directory (str): The directory under `name` to put the file in
354        target (File): A File object to symlink to
355
356    Returns:
357        File: A newly generated symlink file
358    """
359    symlink = ctx.actions.declare_file("{}/{}/{}".format(
360        name,
361        directory,
362        target.basename,
363    ))
364
365    ctx.actions.symlink(
366        output = symlink,
367        target_file = target,
368        is_executable = True,
369    )
370
371    return symlink
372
373def _generate_sysroot(
374        ctx,
375        rustc,
376        rustdoc,
377        rustc_lib,
378        cargo = None,
379        clippy = None,
380        cargo_clippy = None,
381        llvm_tools = None,
382        rust_std = None,
383        rustfmt = None):
384    """Generate a rust sysroot from collection of toolchain components
385
386    Args:
387        ctx (ctx): A context object from a `rust_toolchain` rule.
388        rustc (File): The path to a `rustc` executable.
389        rustdoc (File): The path to a `rustdoc` executable.
390        rustc_lib (Target): A collection of Files containing dependencies of `rustc`.
391        cargo (File, optional): The path to a `cargo` executable.
392        cargo_clippy (File, optional): The path to a `cargo-clippy` executable.
393        clippy (File, optional): The path to a `clippy-driver` executable.
394        llvm_tools (Target, optional): A collection of llvm tools used by `rustc`.
395        rust_std (Target, optional): A collection of Files containing Rust standard library components.
396        rustfmt (File, optional): The path to a `rustfmt` executable.
397
398    Returns:
399        struct: A struct of generated files representing the new sysroot
400    """
401    name = ctx.label.name
402
403    # Define runfiles
404    direct_files = []
405    transitive_file_sets = []
406
407    # Rustc
408    sysroot_rustc = _symlink_sysroot_bin(ctx, name, "bin", rustc)
409    direct_files.extend([sysroot_rustc])
410
411    # Rustc dependencies
412    sysroot_rustc_lib = None
413    if rustc_lib:
414        sysroot_rustc_lib = _symlink_sysroot_tree(ctx, name, rustc_lib)
415        transitive_file_sets.extend([sysroot_rustc_lib])
416
417    # Rustdoc
418    sysroot_rustdoc = _symlink_sysroot_bin(ctx, name, "bin", rustdoc)
419    direct_files.extend([sysroot_rustdoc])
420
421    # Clippy
422    sysroot_clippy = None
423    if clippy:
424        sysroot_clippy = _symlink_sysroot_bin(ctx, name, "bin", clippy)
425        direct_files.extend([sysroot_clippy])
426
427    # Cargo
428    sysroot_cargo = None
429    if cargo:
430        sysroot_cargo = _symlink_sysroot_bin(ctx, name, "bin", cargo)
431        direct_files.extend([sysroot_cargo])
432
433    # Cargo-clippy
434    sysroot_cargo_clippy = None
435    if cargo_clippy:
436        sysroot_cargo_clippy = _symlink_sysroot_bin(ctx, name, "bin", cargo_clippy)
437        direct_files.extend([sysroot_cargo_clippy])
438
439    # Rustfmt
440    sysroot_rustfmt = None
441    if rustfmt:
442        sysroot_rustfmt = _symlink_sysroot_bin(ctx, name, "bin", rustfmt)
443        direct_files.extend([sysroot_rustfmt])
444
445    # Llvm tools
446    sysroot_llvm_tools = None
447    if llvm_tools:
448        sysroot_llvm_tools = _symlink_sysroot_tree(ctx, name, llvm_tools)
449        transitive_file_sets.extend([sysroot_llvm_tools])
450
451    # Rust standard library
452    sysroot_rust_std = None
453    if rust_std:
454        sysroot_rust_std = _symlink_sysroot_tree(ctx, name, rust_std)
455        transitive_file_sets.extend([sysroot_rust_std])
456
457        # Made available to support $(location) expansion in stdlib_linkflags and extra_rustc_flags.
458        transitive_file_sets.append(depset(ctx.files.rust_std))
459
460    # Declare a file in the root of the sysroot to make locating the sysroot easy
461    sysroot_anchor = ctx.actions.declare_file("{}/rust.sysroot".format(name))
462    ctx.actions.write(
463        output = sysroot_anchor,
464        content = "\n".join([
465            "cargo: {}".format(cargo),
466            "clippy: {}".format(clippy),
467            "cargo-clippy: {}".format(cargo_clippy),
468            "llvm_tools: {}".format(llvm_tools),
469            "rust_std: {}".format(rust_std),
470            "rustc_lib: {}".format(rustc_lib),
471            "rustc: {}".format(rustc),
472            "rustdoc: {}".format(rustdoc),
473            "rustfmt: {}".format(rustfmt),
474        ]),
475    )
476
477    # Create a depset of all sysroot files (symlinks and their real paths)
478    all_files = depset(direct_files, transitive = transitive_file_sets)
479
480    return struct(
481        all_files = all_files,
482        cargo = sysroot_cargo,
483        clippy = sysroot_clippy,
484        cargo_clippy = sysroot_cargo_clippy,
485        rust_std = sysroot_rust_std,
486        rustc = sysroot_rustc,
487        rustc_lib = sysroot_rustc_lib,
488        rustdoc = sysroot_rustdoc,
489        rustfmt = sysroot_rustfmt,
490        sysroot_anchor = sysroot_anchor,
491    )
492
493def _experimental_use_cc_common_link(ctx):
494    return ctx.attr.experimental_use_cc_common_link[BuildSettingInfo].value
495
496def _rust_toolchain_impl(ctx):
497    """The rust_toolchain implementation
498
499    Args:
500        ctx (ctx): The rule's context object
501
502    Returns:
503        list: A list containing the target's toolchain Provider info
504    """
505    compilation_mode_opts = {}
506    for k, opt_level in ctx.attr.opt_level.items():
507        if not k in ctx.attr.debug_info:
508            fail("Compilation mode {} is not defined in debug_info but is defined opt_level".format(k))
509        if not k in ctx.attr.strip_level:
510            fail("Compilation mode {} is not defined in strip_level but is defined opt_level".format(k))
511        compilation_mode_opts[k] = struct(debug_info = ctx.attr.debug_info[k], opt_level = opt_level, strip_level = ctx.attr.strip_level[k])
512    for k in ctx.attr.debug_info.keys():
513        if not k in ctx.attr.opt_level:
514            fail("Compilation mode {} is not defined in opt_level but is defined debug_info".format(k))
515
516    rename_first_party_crates = ctx.attr._rename_first_party_crates[BuildSettingInfo].value
517    third_party_dir = ctx.attr._third_party_dir[BuildSettingInfo].value
518    pipelined_compilation = ctx.attr._pipelined_compilation[BuildSettingInfo].value
519    no_std = ctx.attr._no_std[BuildSettingInfo].value
520
521    experimental_use_global_allocator = ctx.attr._experimental_use_global_allocator[BuildSettingInfo].value
522    if _experimental_use_cc_common_link(ctx):
523        if experimental_use_global_allocator and not ctx.attr.global_allocator_library:
524            fail("rust_toolchain.experimental_use_cc_common_link with --@rules_rust//rust/settings:experimental_use_global_allocator " +
525                 "requires rust_toolchain.global_allocator_library to be set")
526        if not ctx.attr.allocator_library:
527            fail("rust_toolchain.experimental_use_cc_common_link requires rust_toolchain.allocator_library to be set")
528    if experimental_use_global_allocator and not _experimental_use_cc_common_link(ctx):
529        fail(
530            "Using @rules_rust//rust/settings:experimental_use_global_allocator requires" +
531            "--@rules_rust//rust/settings:experimental_use_cc_common_link to be set",
532        )
533
534    rust_std = ctx.attr.rust_std
535
536    sysroot = _generate_sysroot(
537        ctx = ctx,
538        rustc = ctx.file.rustc,
539        rustdoc = ctx.file.rust_doc,
540        rustc_lib = ctx.attr.rustc_lib,
541        rust_std = rust_std,
542        rustfmt = ctx.file.rustfmt,
543        clippy = ctx.file.clippy_driver,
544        cargo = ctx.file.cargo,
545        cargo_clippy = ctx.file.cargo_clippy,
546        llvm_tools = ctx.attr.llvm_tools,
547    )
548
549    expanded_stdlib_linkflags = []
550    for flag in ctx.attr.stdlib_linkflags:
551        expanded_stdlib_linkflags.append(
552            dedup_expand_location(
553                ctx,
554                flag,
555                targets = rust_std[rust_common.stdlib_info].srcs,
556            ),
557        )
558
559    expanded_extra_rustc_flags = []
560    for flag in ctx.attr.extra_rustc_flags:
561        expanded_extra_rustc_flags.append(
562            dedup_expand_location(
563                ctx,
564                flag,
565                targets = rust_std[rust_common.stdlib_info].srcs,
566            ),
567        )
568
569    linking_context = cc_common.create_linking_context(
570        linker_inputs = depset([
571            cc_common.create_linker_input(
572                owner = ctx.label,
573                user_link_flags = depset(expanded_stdlib_linkflags),
574            ),
575        ]),
576    )
577
578    # Contains linker flags needed to link Rust standard library.
579    # These need to be added to linker command lines when the linker is not rustc
580    # (rustc does this automatically). Linker flags wrapped in an otherwise empty
581    # `CcInfo` to provide the flags in a way that doesn't duplicate them per target
582    # providing a `CcInfo`.
583    stdlib_linkflags_cc_info = CcInfo(
584        compilation_context = cc_common.create_compilation_context(),
585        linking_context = linking_context,
586    )
587
588    # Determine the path and short_path of the sysroot
589    sysroot_path = sysroot.sysroot_anchor.dirname
590    sysroot_short_path, _, _ = sysroot.sysroot_anchor.short_path.rpartition("/")
591
592    # Variables for make variable expansion
593    make_variables = {
594        "RUSTC": sysroot.rustc.path,
595        "RUSTDOC": sysroot.rustdoc.path,
596        "RUST_DEFAULT_EDITION": ctx.attr.default_edition or "",
597        "RUST_SYSROOT": sysroot_path,
598        "RUST_SYSROOT_SHORT": sysroot_short_path,
599    }
600
601    if sysroot.cargo:
602        make_variables.update({
603            "CARGO": sysroot.cargo.path,
604        })
605
606    if sysroot.rustfmt:
607        make_variables.update({
608            "RUSTFMT": sysroot.rustfmt.path,
609        })
610
611    make_variable_info = platform_common.TemplateVariableInfo(make_variables)
612
613    exec_triple = triple(ctx.attr.exec_triple)
614
615    if not exec_triple.system:
616        fail("No system was provided for the execution platform. Please update {}".format(
617            ctx.label,
618        ))
619
620    if ctx.attr.target_triple and ctx.attr.target_json:
621        fail("Do not specify both target_triple and target_json, either use a builtin triple or provide a custom specification file. Please update {}".format(
622            ctx.label,
623        ))
624
625    target_triple = None
626    target_json = None
627    target_arch = None
628    target_os = None
629
630    if ctx.attr.target_triple:
631        target_triple = triple(ctx.attr.target_triple)
632        target_arch = target_triple.arch
633        target_os = target_triple.system
634
635    elif ctx.attr.target_json:
636        # Ensure the data provided is valid json
637        target_json_content = json.decode(ctx.attr.target_json)
638        target_json = ctx.actions.declare_file("{}.target.json".format(ctx.label.name))
639
640        ctx.actions.write(
641            output = target_json,
642            content = json.encode_indent(target_json_content, indent = " " * 4),
643        )
644
645        if "arch" in target_json_content:
646            target_arch = target_json_content["arch"]
647        if "os" in target_json_content:
648            target_os = target_json_content["os"]
649    else:
650        fail("Either `target_triple` or `target_json` must be provided. Please update {}".format(
651            ctx.label,
652        ))
653
654    toolchain = platform_common.ToolchainInfo(
655        all_files = sysroot.all_files,
656        binary_ext = ctx.attr.binary_ext,
657        cargo = sysroot.cargo,
658        clippy_driver = sysroot.clippy,
659        cargo_clippy = sysroot.cargo_clippy,
660        compilation_mode_opts = compilation_mode_opts,
661        crosstool_files = ctx.files._cc_toolchain,
662        default_edition = ctx.attr.default_edition,
663        dylib_ext = ctx.attr.dylib_ext,
664        env = ctx.attr.env,
665        exec_triple = exec_triple,
666        libstd_and_allocator_ccinfo = _make_libstd_and_allocator_ccinfo(ctx, rust_std, ctx.attr.allocator_library, "std"),
667        libstd_and_global_allocator_ccinfo = _make_libstd_and_allocator_ccinfo(ctx, rust_std, ctx.attr.global_allocator_library, "std"),
668        nostd_and_global_allocator_cc_info = _make_libstd_and_allocator_ccinfo(ctx, rust_std, ctx.attr.global_allocator_library, "no_std_with_alloc"),
669        llvm_cov = ctx.file.llvm_cov,
670        llvm_profdata = ctx.file.llvm_profdata,
671        make_variables = make_variable_info,
672        rust_doc = sysroot.rustdoc,
673        rust_std = sysroot.rust_std,
674        rust_std_paths = depset([file.dirname for file in sysroot.rust_std.to_list()]),
675        rustc = sysroot.rustc,
676        rustc_lib = sysroot.rustc_lib,
677        rustfmt = sysroot.rustfmt,
678        staticlib_ext = ctx.attr.staticlib_ext,
679        stdlib_linkflags = stdlib_linkflags_cc_info,
680        extra_rustc_flags = expanded_extra_rustc_flags,
681        extra_rustc_flags_for_crate_types = ctx.attr.extra_rustc_flags_for_crate_types,
682        extra_exec_rustc_flags = ctx.attr.extra_exec_rustc_flags,
683        per_crate_rustc_flags = ctx.attr.per_crate_rustc_flags,
684        sysroot = sysroot_path,
685        sysroot_short_path = sysroot_short_path,
686        target_arch = target_arch,
687        target_flag_value = target_json.path if target_json else target_triple.str,
688        target_json = target_json,
689        target_os = target_os,
690        target_triple = target_triple,
691
692        # Experimental and incompatible flags
693        _rename_first_party_crates = rename_first_party_crates,
694        _third_party_dir = third_party_dir,
695        _pipelined_compilation = pipelined_compilation,
696        _experimental_link_std_dylib = _experimental_link_std_dylib(ctx),
697        _experimental_use_cc_common_link = _experimental_use_cc_common_link(ctx),
698        _experimental_use_global_allocator = experimental_use_global_allocator,
699        _experimental_use_coverage_metadata_files = ctx.attr._experimental_use_coverage_metadata_files[BuildSettingInfo].value,
700        _experimental_toolchain_generated_sysroot = ctx.attr._experimental_toolchain_generated_sysroot[IncompatibleFlagInfo].enabled,
701        _incompatible_no_rustc_sysroot_env = ctx.attr._incompatible_no_rustc_sysroot_env[IncompatibleFlagInfo].enabled,
702        _no_std = no_std,
703    )
704    return [
705        toolchain,
706        make_variable_info,
707    ]
708
709def _experimental_link_std_dylib(ctx):
710    return not is_exec_configuration(ctx) and \
711           ctx.attr.experimental_link_std_dylib[BuildSettingInfo].value and \
712           ctx.attr.rust_std[rust_common.stdlib_info].std_dylib != None
713
714rust_toolchain = rule(
715    implementation = _rust_toolchain_impl,
716    fragments = ["cpp"],
717    attrs = {
718        "allocator_library": attr.label(
719            doc = "Target that provides allocator functions when rust_library targets are embedded in a cc_binary.",
720            default = "@rules_rust//ffi/cc/allocator_library",
721        ),
722        "binary_ext": attr.string(
723            doc = "The extension for binaries created from rustc.",
724            mandatory = True,
725        ),
726        "cargo": attr.label(
727            doc = "The location of the `cargo` binary. Can be a direct source or a filegroup containing one item.",
728            allow_single_file = True,
729            cfg = "exec",
730        ),
731        "cargo_clippy": attr.label(
732            doc = "The location of the `cargo_clippy` binary. Can be a direct source or a filegroup containing one item.",
733            allow_single_file = True,
734            cfg = "exec",
735        ),
736        "clippy_driver": attr.label(
737            doc = "The location of the `clippy-driver` binary. Can be a direct source or a filegroup containing one item.",
738            allow_single_file = True,
739            cfg = "exec",
740        ),
741        "debug_info": attr.string_dict(
742            doc = "Rustc debug info levels per opt level",
743            default = {
744                "dbg": "2",
745                "fastbuild": "0",
746                "opt": "0",
747            },
748        ),
749        "default_edition": attr.string(
750            doc = (
751                "The edition to use for rust_* rules that don't specify an edition. " +
752                "If absent, every rule is required to specify its `edition` attribute."
753            ),
754        ),
755        "dylib_ext": attr.string(
756            doc = "The extension for dynamic libraries created from rustc.",
757            mandatory = True,
758        ),
759        "env": attr.string_dict(
760            doc = "Environment variables to set in actions.",
761        ),
762        "exec_triple": attr.string(
763            doc = (
764                "The platform triple for the toolchains execution environment. " +
765                "For more details see: https://docs.bazel.build/versions/master/skylark/rules.html#configurations"
766            ),
767            mandatory = True,
768        ),
769        "experimental_link_std_dylib": attr.label(
770            default = Label("@rules_rust//rust/settings:experimental_link_std_dylib"),
771            doc = "Label to a boolean build setting that controls whether whether to link libstd dynamically.",
772        ),
773        "experimental_use_cc_common_link": attr.label(
774            default = Label("//rust/settings:experimental_use_cc_common_link"),
775            doc = "Label to a boolean build setting that controls whether cc_common.link is used to link rust binaries.",
776        ),
777        "extra_exec_rustc_flags": attr.string_list(
778            doc = "Extra flags to pass to rustc in exec configuration",
779        ),
780        "extra_rustc_flags": attr.string_list(
781            doc = "Extra flags to pass to rustc in non-exec configuration. Subject to location expansion with respect to the srcs of the `rust_std` attribute.",
782        ),
783        "extra_rustc_flags_for_crate_types": attr.string_list_dict(
784            doc = "Extra flags to pass to rustc based on crate type",
785        ),
786        "global_allocator_library": attr.label(
787            doc = "Target that provides allocator functions for when a global allocator is present.",
788            default = "@rules_rust//ffi/cc/global_allocator_library",
789        ),
790        "llvm_cov": attr.label(
791            doc = "The location of the `llvm-cov` binary. Can be a direct source or a filegroup containing one item. If None, rust code is not instrumented for coverage.",
792            allow_single_file = True,
793            cfg = "exec",
794        ),
795        "llvm_profdata": attr.label(
796            doc = "The location of the `llvm-profdata` binary. Can be a direct source or a filegroup containing one item. If `llvm_cov` is None, this can be None as well and rust code is not instrumented for coverage.",
797            allow_single_file = True,
798            cfg = "exec",
799        ),
800        "llvm_tools": attr.label(
801            doc = "LLVM tools that are shipped with the Rust toolchain.",
802            allow_files = True,
803        ),
804        "opt_level": attr.string_dict(
805            doc = "Rustc optimization levels.",
806            default = {
807                "dbg": "0",
808                "fastbuild": "0",
809                "opt": "3",
810            },
811        ),
812        "per_crate_rustc_flags": attr.string_list(
813            doc = "Extra flags to pass to rustc in non-exec configuration",
814        ),
815        "rust_doc": attr.label(
816            doc = "The location of the `rustdoc` binary. Can be a direct source or a filegroup containing one item.",
817            allow_single_file = True,
818            cfg = "exec",
819            mandatory = True,
820        ),
821        "rust_std": attr.label(
822            doc = "The Rust standard library.",
823            mandatory = True,
824        ),
825        "rustc": attr.label(
826            doc = "The location of the `rustc` binary. Can be a direct source or a filegroup containing one item.",
827            allow_single_file = True,
828            cfg = "exec",
829            mandatory = True,
830        ),
831        "rustc_lib": attr.label(
832            doc = "The libraries used by rustc during compilation.",
833            cfg = "exec",
834        ),
835        "rustfmt": attr.label(
836            doc = "**Deprecated**: Instead see [rustfmt_toolchain](#rustfmt_toolchain)",
837            allow_single_file = True,
838            cfg = "exec",
839        ),
840        "staticlib_ext": attr.string(
841            doc = "The extension for static libraries created from rustc.",
842            mandatory = True,
843        ),
844        "stdlib_linkflags": attr.string_list(
845            doc = (
846                "Additional linker flags to use when Rust standard library is linked by a C++ linker " +
847                "(rustc will deal with these automatically). Subject to location expansion with respect " +
848                "to the srcs of the `rust_std` attribute."
849            ),
850            mandatory = True,
851        ),
852        "strip_level": attr.string_dict(
853            doc = (
854                "Rustc strip levels. For all potential options, see " +
855                "https://doc.rust-lang.org/rustc/codegen-options/index.html#strip"
856            ),
857            default = {
858                "dbg": "none",
859                "fastbuild": "none",
860                "opt": "debuginfo",
861            },
862        ),
863        "target_json": attr.string(
864            doc = ("Override the target_triple with a custom target specification. " +
865                   "For more details see: https://doc.rust-lang.org/rustc/targets/custom.html"),
866        ),
867        "target_triple": attr.string(
868            doc = (
869                "The platform triple for the toolchains target environment. " +
870                "For more details see: https://docs.bazel.build/versions/master/skylark/rules.html#configurations"
871            ),
872        ),
873        "_cc_toolchain": attr.label(
874            default = Label("@bazel_tools//tools/cpp:current_cc_toolchain"),
875        ),
876        "_experimental_toolchain_generated_sysroot": attr.label(
877            default = Label("//rust/settings:experimental_toolchain_generated_sysroot"),
878            doc = (
879                "Label to a boolean build setting that lets the rule knows wheter to set --sysroot to rustc" +
880                "This flag is only relevant when used together with --@rules_rust//rust/settings:experimental_toolchain_generated_sysroot."
881            ),
882        ),
883        "_experimental_use_coverage_metadata_files": attr.label(
884            default = Label("//rust/settings:experimental_use_coverage_metadata_files"),
885        ),
886        "_experimental_use_global_allocator": attr.label(
887            default = Label("//rust/settings:experimental_use_global_allocator"),
888            doc = (
889                "Label to a boolean build setting that informs the target build whether a global allocator is being used." +
890                "This flag is only relevant when used together with --@rules_rust//rust/settings:experimental_use_global_allocator."
891            ),
892        ),
893        "_incompatible_no_rustc_sysroot_env": attr.label(
894            default = Label("//rust/settings:incompatible_no_rustc_sysroot_env"),
895        ),
896        "_no_std": attr.label(
897            default = Label("//:no_std"),
898        ),
899        "_pipelined_compilation": attr.label(
900            default = Label("//rust/settings:pipelined_compilation"),
901        ),
902        "_rename_first_party_crates": attr.label(
903            default = Label("//rust/settings:rename_first_party_crates"),
904        ),
905        "_third_party_dir": attr.label(
906            default = Label("//rust/settings:third_party_dir"),
907        ),
908    },
909    toolchains = [
910        "@bazel_tools//tools/cpp:toolchain_type",
911    ],
912    doc = """Declares a Rust toolchain for use.
913
914This is for declaring a custom toolchain, eg. for configuring a particular version of rust or supporting a new platform.
915
916Example:
917
918Suppose the core rust team has ported the compiler to a new target CPU, called `cpuX`. This \
919support can be used in Bazel by defining a new toolchain definition and declaration:
920
921```python
922load('@rules_rust//rust:toolchain.bzl', 'rust_toolchain')
923
924rust_toolchain(
925    name = "rust_cpuX_impl",
926    binary_ext = "",
927    dylib_ext = ".so",
928    exec_triple = "cpuX-unknown-linux-gnu",
929    rust_doc = "@rust_cpuX//:rustdoc",
930    rust_std = "@rust_cpuX//:rust_std",
931    rustc = "@rust_cpuX//:rustc",
932    rustc_lib = "@rust_cpuX//:rustc_lib",
933    staticlib_ext = ".a",
934    stdlib_linkflags = ["-lpthread", "-ldl"],
935    target_triple = "cpuX-unknown-linux-gnu",
936)
937
938toolchain(
939    name = "rust_cpuX",
940    exec_compatible_with = [
941        "@platforms//cpu:cpuX",
942        "@platforms//os:linux",
943    ],
944    target_compatible_with = [
945        "@platforms//cpu:cpuX",
946        "@platforms//os:linux",
947    ],
948    toolchain = ":rust_cpuX_impl",
949)
950```
951
952Then, either add the label of the toolchain rule to `register_toolchains` in the WORKSPACE, or pass \
953it to the `"--extra_toolchains"` flag for Bazel, and it will be used.
954
955See `@rules_rust//rust:repositories.bzl` for examples of defining the `@rust_cpuX` repository \
956with the actual binaries and libraries.
957""",
958)
959