Updates & tweaks

Author: helly25

README.md

@@ -125,14 +125,19 @@ for how CC toolchains work in general.
 
 ### Requirements
 
-Version attributes can be requirements of the form `latest:<condition>` or `first:<condition>`.
+Version attributes can be requirements of the form `first`, `first:<condition>`,
+`latest` or `latest:<condition>`.
 
-In case of `latest:`, the latest distribution matching the `condition` will be selected.
+In case of `latest`, the latest distribution matching the optional `condition`
+will be selected.
 
-In case of `first:`, the first distribution matching the `condition` will be selected.
+In case of `first`, the first distribution matching the optional `condition`
+will be selected.
 
-The condition consists of a comma separated list of semver version comparisons supporting `<`, `<=`, `>`, `>=`, `==`, `!=`. Examples:
+The condition consists of a comma separated list of semver version comparisons
+supporting `<`, `<=`, `>`, `>=`, `==`, `!=`. Examples:
 
+- `latest`
 - `latest:>=20.1.0`
 - `latest:>17.0.4,!=19.1.7,<=20.1.0`
 - `first:>=15.0.6,<16`

toolchain/internal/configure.bzl

@@ -36,7 +36,7 @@ load(
     _supported_targets = "SUPPORTED_TARGETS",
     _toolchain_tools = "toolchain_tools",
 )
-load("//toolchain/internal:llvm_distributions.bzl", "required_llvm_release_name_rctx")
+load("//toolchain/internal:llvm_distributions.bzl", "is_requirement", "required_llvm_release_name_rctx")
 load(
     "//toolchain/internal:sysroot.bzl",
     _default_sysroot_path = "default_sysroot_path",
@@ -80,7 +80,7 @@ def llvm_config_impl(rctx):
     if not toolchain_root:
         fail("LLVM toolchain root missing for ({}, {})".format(os, arch))
     (_key, llvm_version) = _exec_os_arch_dict_value(rctx, "llvm_versions")
-    if llvm_version.startswith("first") or llvm_version.startswith("latest"):
+    if is_requirement(llvm_version):
         llvm_version, distribution, error = required_llvm_release_name_rctx(rctx, llvm_version)
         if error:
             fail(error)

toolchain/internal/llvm_distributions.bzl

@@ -1018,7 +1018,7 @@ def required_llvm_release_name_rctx(rctx, llvm_version):
         host_info = host_info(rctx),
     )
 
-def _is_requirement(str):
+def is_requirement(str):
     for prefix in ["first", "latest"]:
         if str == prefix or str.startswith(prefix + ":"):
             return True
@@ -1032,7 +1032,7 @@ def _distribution_urls(rctx):
 
     if rctx.attr.distribution == "auto":
         rctx_host_info = host_info(rctx)
-        if _is_requirement(llvm_version):
+        if is_requirement(llvm_version):
             llvm_version, basename, error = _required_llvm_release_name(
                 version_requirements = _parse_version_requirements(llvm_version),
                 all_llvm_distributions = all_llvm_distributions,

toolchain/internal/repo.bzl

@@ -50,9 +50,10 @@ llvm_repo_attrs.update({
     "llvm_version": attr.string(
         doc = ("One of the supported versions of LLVM, e.g. 12.0.0; used with the " +
                "`auto` value for the `distribution` attribute, and as a default value " +
-               "for the `llvm_versions` attribute. This value can be set to `latest` " +
-               "in order to find the latest LLVM version supported on the OS/arch. " +
-               "Further, requirements can be provided, e.g. `latest:>=17.0.4,!=19.0.7`."),
+               "for the `llvm_versions` attribute. This value can be set to `first` or " +
+               "`latest` in order to find the respective first or latest LLVM version " +
+               "supported on the OS/arch. Further, requirements can be provided, e.g. " +
+               "`latest:>=17.0.4,!=19.0.7`."),
     ),
     "extra_llvm_distributions": attr.string_dict(
         mandatory = False,