From c9dda0e919906f5f534e0f05458e7ee74ea13f1e Mon Sep 17 00:00:00 2001
From: Joshua Kurland <jkurland@roku.com>
Date: Fri, 9 Aug 2024 15:07:07 +0100
Subject: [PATCH 1/7] Allow user provided platform constraints

---
 toolchain/extensions/llvm.bzl    | 36 ++++++++++++++++++++++++++++++++
 toolchain/internal/configure.bzl | 12 +++++++++--
 toolchain/internal/repo.bzl      |  8 +++++++
 3 files changed, 54 insertions(+), 2 deletions(-)

diff --git a/toolchain/extensions/llvm.bzl b/toolchain/extensions/llvm.bzl
index e38b783a..28148719 100644
--- a/toolchain/extensions/llvm.bzl
+++ b/toolchain/extensions/llvm.bzl
@@ -34,6 +34,20 @@ def _root_dict(roots, cls, name, strip_target):
 
     return res
 
+def _constraint_dict(tags, name):
+    constraints = {}
+
+    # Gather all the additional constraints for each target
+    for tag in tags:
+        targets = list(tag.targets)
+        if not targets:
+            targets = [""]
+        for target in targets:
+            constraints_for_target = constraints.setdefault(target, [])
+            constraints_for_target.extend([str(c) for c in tag.constraints])
+
+    return constraints
+
 def _llvm_impl_(module_ctx):
     for mod in module_ctx.modules:
         if not mod.is_root:
@@ -49,6 +63,14 @@ def _llvm_impl_(module_ctx):
             }
             attrs["toolchain_roots"] = _root_dict([root for root in mod.tags.toolchain_root if root.name == name], "toolchain_root", name, True)
             attrs["sysroot"] = _root_dict([sysroot for sysroot in mod.tags.sysroot if sysroot.name == name], "sysroot", name, False)
+            attrs["extra_exec_compatible_with"] = _constraint_dict(
+                [tag for tag in mod.tags.extra_exec_compatible_with if tag.name == name],
+                name,
+            )
+            attrs["extra_target_compatible_with"] = _constraint_dict(
+                [tag for tag in mod.tags.extra_target_compatible_with if tag.name == name],
+                name,
+            )
 
             llvm_toolchain(
                 **attrs
@@ -95,5 +117,19 @@ llvm = module_extension(
                 "path": attr.string(doc = "Absolute path to the sysroot."),
             },
         ),
+        "extra_exec_compatible_with": tag_class(
+            attrs = {
+                "name": attr.string(doc = "Same name as the toolchain tag.", default = "llvm_toolchain"),
+                "targets": attr.string_list(doc = "Specific targets, if any; empty list means this applies to all."),
+                "constraints": attr.label_list(doc = "List of extra constraints to add to exec_compatible_with for the generated toolchains."),
+            },
+        ),
+        "extra_target_compatible_with": tag_class(
+            attrs = {
+                "name": attr.string(doc = "Same name as the toolchain tag.", default = "llvm_toolchain"),
+                "targets": attr.string_list(doc = "Specific targets, if any; empty list means this applies to all."),
+                "constraints": attr.label_list(doc = "List of extra constraints to add to target_compatible_with for the generated toolchains."),
+            },
+        ),
     },
 )
diff --git a/toolchain/internal/configure.bzl b/toolchain/internal/configure.bzl
index 6e40059c..8731af75 100644
--- a/toolchain/internal/configure.bzl
+++ b/toolchain/internal/configure.bzl
@@ -59,6 +59,8 @@ def _join(path1, path2):
 def llvm_config_impl(rctx):
     _check_os_arch_keys(rctx.attr.sysroot)
     _check_os_arch_keys(rctx.attr.cxx_builtin_include_directories)
+    _check_os_arch_keys(rctx.attr.extra_exec_compatible_with)
+    _check_os_arch_keys(rctx.attr.extra_target_compatible_with)
 
     os = _os(rctx)
     if os == "windows":
@@ -166,6 +168,8 @@ def llvm_config_impl(rctx):
         unfiltered_compile_flags_dict = rctx.attr.unfiltered_compile_flags,
         llvm_version = llvm_version,
         extra_compiler_files = rctx.attr.extra_compiler_files,
+        extra_exec_compatible_with = rctx.attr.extra_exec_compatible_with,
+        extra_target_compatible_with = rctx.attr.extra_target_compatible_with,
     )
     exec_dl_ext = "dylib" if os == "darwin" else "so"
     cc_toolchains_str, toolchain_labels_str = _cc_toolchains_str(
@@ -380,11 +384,11 @@ toolchain(
     exec_compatible_with = [
         "@platforms//cpu:{exec_arch}",
         "@platforms//os:{exec_os_bzl}",
-    ],
+    ] + {extra_exec_compatible_with_specific} + {extra_exec_compatible_with_all_targets},
     target_compatible_with = [
         "@platforms//cpu:{target_arch}",
         "@platforms//os:{target_os_bzl}",
-    ],
+    ] + {extra_target_compatible_with_specific} + {extra_target_compatible_with_all_targets},
     target_settings = {target_settings},
     toolchain = ":cc-clang-{suffix}",
     toolchain_type = "@bazel_tools//tools/cpp:toolchain_type",
@@ -543,6 +547,10 @@ cc_toolchain(
         ]),
         extra_compiler_files = ("\"%s\"," % str(toolchain_info.extra_compiler_files)) if toolchain_info.extra_compiler_files else "",
         major_llvm_version = major_llvm_version,
+        extra_exec_compatible_with_specific = toolchain_info.extra_exec_compatible_with.get(target_pair, []),
+        extra_target_compatible_with_specific = toolchain_info.extra_target_compatible_with.get(target_pair, []),
+        extra_exec_compatible_with_all_targets = toolchain_info.extra_exec_compatible_with.get("", []),
+        extra_target_compatible_with_all_targets = toolchain_info.extra_target_compatible_with.get("", []),
     )
 
 def _convenience_targets_str(rctx, use_absolute_paths, llvm_dist_rel_path, llvm_dist_label_prefix, exec_dl_ext):
diff --git a/toolchain/internal/repo.bzl b/toolchain/internal/repo.bzl
index 27012db6..df89c4c1 100644
--- a/toolchain/internal/repo.bzl
+++ b/toolchain/internal/repo.bzl
@@ -271,6 +271,14 @@ llvm_config_attrs.update({
         default = False,
         doc = "Use absolute paths in the toolchain. Avoids sandbox overhead.",
     ),
+    "extra_exec_compatible_with": attr.string_list_dict(
+        mandatory = False,
+        doc = "Extra constraints to be added to exec_compatible_with for each target",
+    ),
+    "extra_target_compatible_with": attr.string_list_dict(
+        mandatory = False,
+        doc = "Extra constraints to be added to target_compatible_with for each target",
+    ),
     "_cc_toolchain_config_bzl": attr.label(
         default = "//toolchain:cc_toolchain_config.bzl",
     ),

From 034caf2f5e921d93e73d470815f2e07e54057c67 Mon Sep 17 00:00:00 2001
From: Joshua Kurland <jkurland@roku.com>
Date: Fri, 16 Aug 2024 12:36:20 +0100
Subject: [PATCH 2/7] Add a test for extra_target_compatible_with

---
 tests/BUILD.bazel     | 52 ++++++++++++++++++++++++++++++++++++++++++-
 tests/MODULE.bazel    | 18 ++++++++++++++-
 tests/test_define.cc  | 24 ++++++++++++++++++++
 tests/transitions.bzl | 21 +++++++++++++++++
 4 files changed, 113 insertions(+), 2 deletions(-)
 create mode 100644 tests/test_define.cc

diff --git a/tests/BUILD.bazel b/tests/BUILD.bazel
index 940c9577..daefc26f 100644
--- a/tests/BUILD.bazel
+++ b/tests/BUILD.bazel
@@ -14,7 +14,7 @@
 
 load("@bazel_skylib//rules:build_test.bzl", "build_test")
 load("@rules_cc//cc:defs.bzl", "cc_binary", "cc_library", "cc_test")
-load(":transitions.bzl", "dwp_file")
+load(":transitions.bzl", "dwp_file", "transition_library_to_test_define")
 
 cc_library(
     name = "stdlib",
@@ -139,3 +139,53 @@ toolchain(
     toolchain = "@@rules_foreign_cc~~tools~ninja_1.11.1_mac//:ninja_tool",
     toolchain_type = "@rules_foreign_cc//toolchains:ninja_toolchain",
 )
+
+# Testing extra_target_compatible_with
+constraint_setting(
+    name = "with_test_define",
+    default_constraint_value = ":no_test_define",
+    visibility = ["//visibility:public"],
+)
+
+constraint_value(
+    name = "no_test_define",
+    constraint_setting = ":with_test_define",
+    visibility = ["//visibility:public"],
+)
+
+constraint_value(
+    name = "yes_test_define",
+    constraint_setting = ":with_test_define",
+    visibility = ["//visibility:public"],
+)
+
+platform(
+    name = "platform_with_test_define",
+    constraint_values = [
+        ":yes_test_define",
+    ],
+    parents = ["@bazel_tools//tools:host_platform"],
+    visibility = ["//visibility:public"],
+)
+
+cc_library(
+    name = "test_define_lib",
+    srcs = ["test_define.cc"],
+)
+
+cc_test(
+    name = "test_define_no_define",
+    args = ["no"],
+    deps = [":test_define_lib"],
+)
+
+transition_library_to_test_define(
+    name = "test_define_lib_with_define",
+    lib = ":test_define_lib",
+)
+
+cc_test(
+    name = "test_define_yes_define",
+    args = ["yes"],
+    deps = [":test_define_lib_with_define"],
+)
diff --git a/tests/MODULE.bazel b/tests/MODULE.bazel
index 126b4dd3..d733db24 100644
--- a/tests/MODULE.bazel
+++ b/tests/MODULE.bazel
@@ -66,10 +66,26 @@ llvm.toolchain(
     name = "llvm_toolchain",
     llvm_versions = LLVM_VERSIONS,
 )
+llvm.extra_target_compatible_with(
+    name = "llvm_toolchain",
+    constraints = ["@//:no_test_define"],
+)
 use_repo(llvm, "llvm_toolchain", "llvm_toolchain_llvm")
-
 register_toolchains("@llvm_toolchain//:all")
 
+llvm.toolchain(
+    name = "llvm_toolchain_with_define",
+    llvm_versions = LLVM_VERSIONS,
+    cxx_flags = {"": ["-DTEST_DEFINE", "-stdlib=libc++"]},
+)
+llvm.extra_target_compatible_with(
+    name = "llvm_toolchain_with_define",
+    constraints = ["//:yes_test_define"],
+)
+use_repo(llvm, "llvm_toolchain_with_define")
+register_toolchains("@llvm_toolchain_with_define//:all")
+
+
 # Example toolchain with user provided URLs.
 # TODO(siddharthab): Add test.
 llvm.toolchain(
diff --git a/tests/test_define.cc b/tests/test_define.cc
new file mode 100644
index 00000000..450e95dd
--- /dev/null
+++ b/tests/test_define.cc
@@ -0,0 +1,24 @@
+#include <string>
+#include <iostream>
+
+int main(int argc, char** argv) {
+    if (argc != 2) {
+        std::cout << "Not enough arguments" << std::endl;
+        return 1;
+    }
+
+    std::string arg = argv[1];
+
+#ifdef TEST_DEFINE
+    if (arg != "yes") {
+        std::cout << "TEST_DEFINE is defined but it was expected to be not defined" << std::endl;
+        return 1;
+    }
+#else
+    if (arg != "no") {
+        std::cout << "TEST_DEFINE is not defined but it was expected to be defined" << std::endl;
+        return 1;
+    }
+#endif
+    return 0;
+}
\ No newline at end of file
diff --git a/tests/transitions.bzl b/tests/transitions.bzl
index 23db8d31..fb5bb969 100644
--- a/tests/transitions.bzl
+++ b/tests/transitions.bzl
@@ -96,3 +96,24 @@ dwp_file = rule(
         ),
     },
 )
+
+def _transition_to_test_define_impl(_, _attr):
+    return {"//command_line_option:platforms": "//:platform_with_test_define"}
+
+_transition_to_test_define = transition(
+    implementation = _transition_to_test_define_impl,
+    inputs = [],
+    outputs = ["//command_line_option:platforms"],
+)
+
+def _transition_library_to_test_define_impl(ctx):
+    return [
+        ctx.attr.lib[0][CcInfo],
+    ]
+
+transition_library_to_test_define = rule(
+    implementation = _transition_library_to_test_define_impl,
+    attrs = {
+        "lib": attr.label(cfg = _transition_to_test_define),
+    },
+)

From 187bb3ddce174a648a29dfdfe9756756efc4e708 Mon Sep 17 00:00:00 2001
From: Joshua Kurland <jkurland@roku.com>
Date: Mon, 19 Aug 2024 10:50:01 +0100
Subject: [PATCH 3/7] Use cxx_standard instead of cxxflags to detect which
 toolchain is used and support workspace

---
 tests/BUILD.bazel          | 41 +++++++++++++++++++-------------------
 tests/MODULE.bazel         | 15 +++++++-------
 tests/WORKSPACE            | 17 ++++++++++++++++
 tests/test_cxx_standard.cc | 22 ++++++++++++++++++++
 tests/test_define.cc       | 24 ----------------------
 tests/transitions.bzl      | 17 ++++++++--------
 6 files changed, 77 insertions(+), 59 deletions(-)
 create mode 100644 tests/test_cxx_standard.cc
 delete mode 100644 tests/test_define.cc

diff --git a/tests/BUILD.bazel b/tests/BUILD.bazel
index daefc26f..a350f976 100644
--- a/tests/BUILD.bazel
+++ b/tests/BUILD.bazel
@@ -14,7 +14,7 @@
 
 load("@bazel_skylib//rules:build_test.bzl", "build_test")
 load("@rules_cc//cc:defs.bzl", "cc_binary", "cc_library", "cc_test")
-load(":transitions.bzl", "dwp_file", "transition_library_to_test_define")
+load(":transitions.bzl", "dwp_file", "transition_library_to_platform")
 
 cc_library(
     name = "stdlib",
@@ -142,50 +142,51 @@ toolchain(
 
 # Testing extra_target_compatible_with
 constraint_setting(
-    name = "with_test_define",
-    default_constraint_value = ":no_test_define",
+    name = "cxx_standard",
+    default_constraint_value = ":cxx17",
     visibility = ["//visibility:public"],
 )
 
 constraint_value(
-    name = "no_test_define",
-    constraint_setting = ":with_test_define",
+    name = "cxx20",
+    constraint_setting = ":cxx_standard",
     visibility = ["//visibility:public"],
 )
 
 constraint_value(
-    name = "yes_test_define",
-    constraint_setting = ":with_test_define",
+    name = "cxx17",
+    constraint_setting = ":cxx_standard",
     visibility = ["//visibility:public"],
 )
 
 platform(
-    name = "platform_with_test_define",
+    name = "cxx20_platform",
     constraint_values = [
-        ":yes_test_define",
+        ":cxx20",
     ],
     parents = ["@bazel_tools//tools:host_platform"],
     visibility = ["//visibility:public"],
 )
 
 cc_library(
-    name = "test_define_lib",
-    srcs = ["test_define.cc"],
+    name = "test_cxx_standard_lib",
+    srcs = ["test_cxx_standard.cc"],
 )
 
 cc_test(
-    name = "test_define_no_define",
-    args = ["no"],
-    deps = [":test_define_lib"],
+    name = "test_cxx_standard_is_17",
+    args = ["201703"],
+    deps = [":test_cxx_standard_lib"],
 )
 
-transition_library_to_test_define(
-    name = "test_define_lib_with_define",
-    lib = ":test_define_lib",
+transition_library_to_platform(
+    name = "test_cxx_standard_lib_transitioned",
+    lib = ":test_cxx_standard_lib",
+    platform = ":cxx20_platform",
 )
 
 cc_test(
-    name = "test_define_yes_define",
-    args = ["yes"],
-    deps = [":test_define_lib_with_define"],
+    name = "test_cxx_standard_is_20",
+    args = ["202002"],
+    deps = [":test_cxx_standard_lib_transitioned"],
 )
diff --git a/tests/MODULE.bazel b/tests/MODULE.bazel
index d733db24..1145b32c 100644
--- a/tests/MODULE.bazel
+++ b/tests/MODULE.bazel
@@ -65,25 +65,26 @@ LLVM_VERSIONS = {
 llvm.toolchain(
     name = "llvm_toolchain",
     llvm_versions = LLVM_VERSIONS,
+    cxx_standard = {"": "c++17"},
 )
 llvm.extra_target_compatible_with(
     name = "llvm_toolchain",
-    constraints = ["@//:no_test_define"],
+    constraints = ["@//:cxx17"],
 )
 use_repo(llvm, "llvm_toolchain", "llvm_toolchain_llvm")
 register_toolchains("@llvm_toolchain//:all")
 
 llvm.toolchain(
-    name = "llvm_toolchain_with_define",
+    name = "llvm_toolchain_cxx20",
     llvm_versions = LLVM_VERSIONS,
-    cxx_flags = {"": ["-DTEST_DEFINE", "-stdlib=libc++"]},
+    cxx_standard = {"": "c++20"},
 )
 llvm.extra_target_compatible_with(
-    name = "llvm_toolchain_with_define",
-    constraints = ["//:yes_test_define"],
+    name = "llvm_toolchain_cxx20",
+    constraints = ["//:cxx20"],
 )
-use_repo(llvm, "llvm_toolchain_with_define")
-register_toolchains("@llvm_toolchain_with_define//:all")
+use_repo(llvm, "llvm_toolchain_cxx20")
+register_toolchains("@llvm_toolchain_cxx20//:all")
 
 
 # Example toolchain with user provided URLs.
diff --git a/tests/WORKSPACE b/tests/WORKSPACE
index 04129246..ab9181dd 100644
--- a/tests/WORKSPACE
+++ b/tests/WORKSPACE
@@ -37,6 +37,19 @@ LLVM_VERSIONS = {
 
 llvm_toolchain(
     name = "llvm_toolchain",
+    cxx_standard = {"": "c++17"},
+    extra_target_compatible_with = {
+        "": ["@//:cxx17"],
+    },
+    llvm_versions = LLVM_VERSIONS,
+)
+
+llvm_toolchain(
+    name = "llvm_toolchain_cxx20",
+    cxx_standard = {"": "c++20"},
+    extra_target_compatible_with = {
+        "": ["@//:cxx20"],
+    },
     llvm_versions = LLVM_VERSIONS,
 )
 
@@ -75,6 +88,10 @@ load("@llvm_toolchain//:toolchains.bzl", "llvm_register_toolchains")
 
 llvm_register_toolchains()
 
+load("@llvm_toolchain_cxx20//:toolchains.bzl", llvm_register_toolchains_cxx20 = "llvm_register_toolchains")
+
+llvm_register_toolchains_cxx20()
+
 ## Toolchain example with absolute paths; tested in GitHub CI.
 llvm_toolchain(
     name = "llvm_toolchain_with_absolute_paths",
diff --git a/tests/test_cxx_standard.cc b/tests/test_cxx_standard.cc
new file mode 100644
index 00000000..7d383aee
--- /dev/null
+++ b/tests/test_cxx_standard.cc
@@ -0,0 +1,22 @@
+#include <iostream>
+#include <cstdlib>
+
+int main(int argc, char** argv) {
+    if (argc != 2) {
+        std::cout << "Not enough arguments" << std::endl;
+        return 1;
+    }
+
+    long expected_version = std::atol(argv[1]);
+
+    if (expected_version == 0) {
+        std::cout << "Invalid version argument, must be an integer" << std::endl;
+        return 1;
+    }
+
+    if (expected_version != __cplusplus) {
+        std::cout << "Expected version to be " << argv[1] << " but got " << __cplusplus << std::endl;
+        return 1;
+    }
+    return 0;
+}
\ No newline at end of file
diff --git a/tests/test_define.cc b/tests/test_define.cc
deleted file mode 100644
index 450e95dd..00000000
--- a/tests/test_define.cc
+++ /dev/null
@@ -1,24 +0,0 @@
-#include <string>
-#include <iostream>
-
-int main(int argc, char** argv) {
-    if (argc != 2) {
-        std::cout << "Not enough arguments" << std::endl;
-        return 1;
-    }
-
-    std::string arg = argv[1];
-
-#ifdef TEST_DEFINE
-    if (arg != "yes") {
-        std::cout << "TEST_DEFINE is defined but it was expected to be not defined" << std::endl;
-        return 1;
-    }
-#else
-    if (arg != "no") {
-        std::cout << "TEST_DEFINE is not defined but it was expected to be defined" << std::endl;
-        return 1;
-    }
-#endif
-    return 0;
-}
\ No newline at end of file
diff --git a/tests/transitions.bzl b/tests/transitions.bzl
index fb5bb969..33938337 100644
--- a/tests/transitions.bzl
+++ b/tests/transitions.bzl
@@ -97,23 +97,24 @@ dwp_file = rule(
     },
 )
 
-def _transition_to_test_define_impl(_, _attr):
-    return {"//command_line_option:platforms": "//:platform_with_test_define"}
+def _transition_library_to_platform_transition_impl(_, attr):
+    return {"//command_line_option:platforms": str(attr.platform)}
 
-_transition_to_test_define = transition(
-    implementation = _transition_to_test_define_impl,
+_transition_library_to_platform_transition = transition(
+    implementation = _transition_library_to_platform_transition_impl,
     inputs = [],
     outputs = ["//command_line_option:platforms"],
 )
 
-def _transition_library_to_test_define_impl(ctx):
+def _transition_library_to_platform_impl(ctx):
     return [
         ctx.attr.lib[0][CcInfo],
     ]
 
-transition_library_to_test_define = rule(
-    implementation = _transition_library_to_test_define_impl,
+transition_library_to_platform = rule(
+    implementation = _transition_library_to_platform_impl,
     attrs = {
-        "lib": attr.label(cfg = _transition_to_test_define),
+        "lib": attr.label(mandatory = True, cfg = _transition_library_to_platform_transition),
+        "platform": attr.label(mandatory = True),
     },
 )

From 7849f229142416abfc95a5eb7e136c676872aa02 Mon Sep 17 00:00:00 2001
From: Joshua Kurland <jkurland@roku.com>
Date: Tue, 20 Aug 2024 10:46:42 +0100
Subject: [PATCH 4/7] Use old host platform label, add
 function_transition_allowlist to platform transition rule

---
 tests/BUILD.bazel     | 4 +++-
 tests/transitions.bzl | 3 +++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/tests/BUILD.bazel b/tests/BUILD.bazel
index a350f976..0548b7f4 100644
--- a/tests/BUILD.bazel
+++ b/tests/BUILD.bazel
@@ -164,7 +164,7 @@ platform(
     constraint_values = [
         ":cxx20",
     ],
-    parents = ["@bazel_tools//tools:host_platform"],
+    parents = ["@platforms//host"],
     visibility = ["//visibility:public"],
 )
 
@@ -175,6 +175,7 @@ cc_library(
 
 cc_test(
     name = "test_cxx_standard_is_17",
+    size = "small",
     args = ["201703"],
     deps = [":test_cxx_standard_lib"],
 )
@@ -187,6 +188,7 @@ transition_library_to_platform(
 
 cc_test(
     name = "test_cxx_standard_is_20",
+    size = "small",
     args = ["202002"],
     deps = [":test_cxx_standard_lib_transitioned"],
 )
diff --git a/tests/transitions.bzl b/tests/transitions.bzl
index 33938337..ac7316ed 100644
--- a/tests/transitions.bzl
+++ b/tests/transitions.bzl
@@ -116,5 +116,8 @@ transition_library_to_platform = rule(
     attrs = {
         "lib": attr.label(mandatory = True, cfg = _transition_library_to_platform_transition),
         "platform": attr.label(mandatory = True),
+        "_allowlist_function_transition": attr.label(
+            default = "@bazel_tools//tools/allowlists/function_transition_allowlist",
+        ),
     },
 )

From 7f73ce490b80fbe454ddc23206bdf384a7800ea2 Mon Sep 17 00:00:00 2001
From: Joshua Kurland <jkurland@roku.com>
Date: Tue, 20 Aug 2024 10:50:26 +0100
Subject: [PATCH 5/7] Try adding a src file to platform constraint tests to see
 if that fixes macos

---
 tests/BUILD.bazel               | 2 ++
 tests/test_cxx_standard.cc      | 4 ++--
 tests/test_cxx_standard_main.cc | 5 +++++
 3 files changed, 9 insertions(+), 2 deletions(-)
 create mode 100644 tests/test_cxx_standard_main.cc

diff --git a/tests/BUILD.bazel b/tests/BUILD.bazel
index 0548b7f4..c1c9f8fe 100644
--- a/tests/BUILD.bazel
+++ b/tests/BUILD.bazel
@@ -176,6 +176,7 @@ cc_library(
 cc_test(
     name = "test_cxx_standard_is_17",
     size = "small",
+    srcs = ["test_cxx_standard_main.cc"],
     args = ["201703"],
     deps = [":test_cxx_standard_lib"],
 )
@@ -189,6 +190,7 @@ transition_library_to_platform(
 cc_test(
     name = "test_cxx_standard_is_20",
     size = "small",
+    srcs = ["test_cxx_standard_main.cc"],
     args = ["202002"],
     deps = [":test_cxx_standard_lib_transitioned"],
 )
diff --git a/tests/test_cxx_standard.cc b/tests/test_cxx_standard.cc
index 7d383aee..26892880 100644
--- a/tests/test_cxx_standard.cc
+++ b/tests/test_cxx_standard.cc
@@ -1,7 +1,7 @@
 #include <iostream>
 #include <cstdlib>
 
-int main(int argc, char** argv) {
+int run_test(int argc, char** argv) {
     if (argc != 2) {
         std::cout << "Not enough arguments" << std::endl;
         return 1;
@@ -19,4 +19,4 @@ int main(int argc, char** argv) {
         return 1;
     }
     return 0;
-}
\ No newline at end of file
+}
diff --git a/tests/test_cxx_standard_main.cc b/tests/test_cxx_standard_main.cc
new file mode 100644
index 00000000..9a388226
--- /dev/null
+++ b/tests/test_cxx_standard_main.cc
@@ -0,0 +1,5 @@
+int run_test(int argc, char** argv);
+
+int main(int argc, char** argv) {
+    return run_test(argc, argv);
+}
\ No newline at end of file

From 49aa18ed95cfca84e73fece55fb9bb715e99fa64 Mon Sep 17 00:00:00 2001
From: Joshua Kurland <jkurland@roku.com>
Date: Thu, 22 Aug 2024 10:44:11 +0100
Subject: [PATCH 6/7] Add c++17 constraint to other toolchains which get
 registered in different tests, add host_platform repo in non bzlmod tests

---
 tests/MODULE.bazel | 30 ++++++++++++++++++++++++++++++
 tests/WORKSPACE    | 37 +++++++++++++++++++++++++++++++++++++
 2 files changed, 67 insertions(+)

diff --git a/tests/MODULE.bazel b/tests/MODULE.bazel
index 1145b32c..7eb07566 100644
--- a/tests/MODULE.bazel
+++ b/tests/MODULE.bazel
@@ -111,6 +111,11 @@ llvm.toolchain(
         "darwin-aarch64": ["https://github.com/llvm/llvm-project/releases/download/llvmorg-15.0.7/clang+llvm-15.0.7-arm64-apple-darwin22.0.tar.xz"],
         "darwin-x86_64": ["https://github.com/llvm/llvm-project/releases/download/llvmorg-15.0.7/clang+llvm-15.0.7-x86_64-apple-darwin21.0.tar.xz"],
     },
+    cxx_standard = {"": "c++17"},
+)
+llvm.extra_target_compatible_with(
+    name = "llvm_toolchain_with_urls",
+    constraints = ["@//:cxx17"],
 )
 use_repo(llvm, "llvm_toolchain_with_urls")
 
@@ -121,6 +126,11 @@ use_repo(llvm, "llvm_toolchain_with_urls")
 llvm.toolchain(
     name = "llvm_toolchain_13_0_0",
     llvm_version = "13.0.0",
+    cxx_standard = {"": "c++17"},
+)
+llvm.extra_target_compatible_with(
+    name = "llvm_toolchain_13_0_0",
+    constraints = ["@//:cxx17"],
 )
 use_repo(llvm, "llvm_toolchain_13_0_0")
 
@@ -129,6 +139,11 @@ llvm.toolchain(
     name = "llvm_toolchain_with_absolute_paths",
     absolute_paths = True,
     llvm_versions = LLVM_VERSIONS,
+    cxx_standard = {"": "c++17"},
+)
+llvm.extra_target_compatible_with(
+    name = "llvm_toolchain_with_absolute_paths",
+    constraints = ["@//:cxx17"],
 )
 # We can share the downloaded LLVM distribution with the first configuration.
 llvm.toolchain_root(
@@ -141,6 +156,11 @@ use_repo(llvm, "llvm_toolchain_with_absolute_paths")
 llvm.toolchain(
     name = "llvm_toolchain_with_system_llvm",
     llvm_versions = LLVM_VERSIONS,
+    cxx_standard = {"": "c++17"},
+)
+llvm.extra_target_compatible_with(
+    name = "llvm_toolchain_with_system_llvm",
+    constraints = ["@//:cxx17"],
 )
 # For this toolchain to work, the LLVM distribution archive would need to be unpacked here.
 llvm.toolchain_root(
@@ -153,6 +173,11 @@ use_repo(llvm, "llvm_toolchain_with_system_llvm")
 llvm.toolchain(
     name = "llvm_toolchain_with_sysroot",
     llvm_versions = LLVM_VERSIONS,
+    cxx_standard = {"": "c++17"},
+)
+llvm.extra_target_compatible_with(
+    name = "llvm_toolchain_with_sysroot",
+    constraints = ["@//:cxx17"],
 )
 # We can share the downloaded LLVM distribution with the first configuration.
 llvm.toolchain_root(
@@ -177,5 +202,10 @@ llvm.toolchain(
     # distribution = "clang+llvm-17.0.6-x86_64-linux-gnu-ubuntu-22.04.tar.xz",
     exec_os = "linux",
     exec_arch = "amd64",
+    cxx_standard = {"": "c++17"},
+)
+llvm.extra_target_compatible_with(
+    name = "llvm_toolchain_linux_exec",
+    constraints = ["@//:cxx17"],
 )
 use_repo(llvm, "llvm_toolchain_linux_exec")
diff --git a/tests/WORKSPACE b/tests/WORKSPACE
index ab9181dd..f2a8af6f 100644
--- a/tests/WORKSPACE
+++ b/tests/WORKSPACE
@@ -57,6 +57,10 @@ llvm_toolchain(
 # TODO(siddharthab): Add test.
 llvm_toolchain(
     name = "llvm_toolchain_with_urls",
+    cxx_standard = {"": "c++17"},
+    extra_target_compatible_with = {
+        "": ["@//:cxx17"],
+    },
     llvm_versions = LLVM_VERSIONS,
     sha256 = {
         "": "38bc7f5563642e73e69ac5626724e206d6d539fbef653541b34cae0ba9c3f036",
@@ -81,6 +85,10 @@ llvm_toolchain(
 # image base-devel as of the time of this writing (23 May 2022).
 llvm_toolchain(
     name = "llvm_toolchain_13_0_0",
+    cxx_standard = {"": "c++17"},
+    extra_target_compatible_with = {
+        "": ["@//:cxx17"],
+    },
     llvm_version = "13.0.0",
 )
 
@@ -96,6 +104,10 @@ llvm_register_toolchains_cxx20()
 llvm_toolchain(
     name = "llvm_toolchain_with_absolute_paths",
     absolute_paths = True,
+    cxx_standard = {"": "c++17"},
+    extra_target_compatible_with = {
+        "": ["@//:cxx17"],
+    },
     llvm_versions = LLVM_VERSIONS,
     # We can share the downloaded LLVM distribution with the first configuration.
     toolchain_roots = {
@@ -106,6 +118,10 @@ llvm_toolchain(
 ## Toolchain example with system LLVM; tested in GitHub CI.
 llvm_toolchain(
     name = "llvm_toolchain_with_system_llvm",
+    cxx_standard = {"": "c++17"},
+    extra_target_compatible_with = {
+        "": ["@//:cxx17"],
+    },
     llvm_versions = LLVM_VERSIONS,
     # For this toolchain to work, the LLVM distribution archive would need to be unpacked here.
     toolchain_roots = {"": "/opt/llvm-16"},
@@ -129,6 +145,10 @@ filegroup(
 
 llvm_toolchain(
     name = "llvm_toolchain_with_sysroot",
+    cxx_standard = {"": "c++17"},
+    extra_target_compatible_with = {
+        "": ["@//:cxx17"],
+    },
     llvm_versions = LLVM_VERSIONS,
     sysroot = {
         "linux-x86_64": "@org_chromium_sysroot_linux_x64//:sysroot",
@@ -145,10 +165,14 @@ bazel_skylib_workspace()
 
 llvm_toolchain(
     name = "llvm_toolchain_linux_exec",
+    cxx_standard = {"": "c++17"},
     exec_arch = "amd64",
     # Option 2:
     # distribution = "clang+llvm-17.0.6-x86_64-linux-gnu-ubuntu-22.04.tar.xz",
     exec_os = "linux",
+    extra_target_compatible_with = {
+        "": ["@//:cxx17"],
+    },
     llvm_version = "17.0.6",
     # Option 1:
     sha256 = {"": "884ee67d647d77e58740c1e645649e29ae9e8a6fe87c1376be0f3a30f3cc9ab3"},
@@ -247,3 +271,16 @@ http_archive(
         "https://ftp.pcre.org/pub/pcre/pcre-8.43.tar.gz",
     ],
 )
+
+http_archive(
+    name = "platforms",
+    sha256 = "218efe8ee736d26a3572663b374a253c012b716d8af0c07e842e82f238a0a7ee",
+    urls = [
+        "https://mirror.bazel.build/github.com/bazelbuild/platforms/releases/download/0.0.10/platforms-0.0.10.tar.gz",
+        "https://github.com/bazelbuild/platforms/releases/download/0.0.10/platforms-0.0.10.tar.gz",
+    ],
+)
+
+load("@platforms//host:extension.bzl", "host_platform_repo")
+
+host_platform_repo(name = "host_platform")

From 659db85963eb8099f383fad8c014026210803929 Mon Sep 17 00:00:00 2001
From: Joshua Kurland <jkurland@roku.com>
Date: Fri, 30 Aug 2024 11:02:37 +0100
Subject: [PATCH 7/7] Only build the c++20 test when the default toolchain is
 being used

---
 tests/BUILD.bazel          |  6 ++++++
 tests/MODULE.bazel         | 30 ------------------------------
 tests/WORKSPACE            | 24 ------------------------
 tests/scripts/run_tests.sh | 12 +++++++++++-
 4 files changed, 17 insertions(+), 55 deletions(-)

diff --git a/tests/BUILD.bazel b/tests/BUILD.bazel
index c1c9f8fe..02ab2032 100644
--- a/tests/BUILD.bazel
+++ b/tests/BUILD.bazel
@@ -192,5 +192,11 @@ cc_test(
     size = "small",
     srcs = ["test_cxx_standard_main.cc"],
     args = ["202002"],
+
+    # Since some platforms require special toolchains (e.g. llvm 13.0.0) this
+    # target won't build on those platforms unless we create a new toolchain per
+    # platform with c++20. So instead just only run this test on platforms that
+    # can use the default toolchain
+    tags = ["manual"],
     deps = [":test_cxx_standard_lib_transitioned"],
 )
diff --git a/tests/MODULE.bazel b/tests/MODULE.bazel
index 7eb07566..1145b32c 100644
--- a/tests/MODULE.bazel
+++ b/tests/MODULE.bazel
@@ -111,11 +111,6 @@ llvm.toolchain(
         "darwin-aarch64": ["https://github.com/llvm/llvm-project/releases/download/llvmorg-15.0.7/clang+llvm-15.0.7-arm64-apple-darwin22.0.tar.xz"],
         "darwin-x86_64": ["https://github.com/llvm/llvm-project/releases/download/llvmorg-15.0.7/clang+llvm-15.0.7-x86_64-apple-darwin21.0.tar.xz"],
     },
-    cxx_standard = {"": "c++17"},
-)
-llvm.extra_target_compatible_with(
-    name = "llvm_toolchain_with_urls",
-    constraints = ["@//:cxx17"],
 )
 use_repo(llvm, "llvm_toolchain_with_urls")
 
@@ -126,11 +121,6 @@ use_repo(llvm, "llvm_toolchain_with_urls")
 llvm.toolchain(
     name = "llvm_toolchain_13_0_0",
     llvm_version = "13.0.0",
-    cxx_standard = {"": "c++17"},
-)
-llvm.extra_target_compatible_with(
-    name = "llvm_toolchain_13_0_0",
-    constraints = ["@//:cxx17"],
 )
 use_repo(llvm, "llvm_toolchain_13_0_0")
 
@@ -139,11 +129,6 @@ llvm.toolchain(
     name = "llvm_toolchain_with_absolute_paths",
     absolute_paths = True,
     llvm_versions = LLVM_VERSIONS,
-    cxx_standard = {"": "c++17"},
-)
-llvm.extra_target_compatible_with(
-    name = "llvm_toolchain_with_absolute_paths",
-    constraints = ["@//:cxx17"],
 )
 # We can share the downloaded LLVM distribution with the first configuration.
 llvm.toolchain_root(
@@ -156,11 +141,6 @@ use_repo(llvm, "llvm_toolchain_with_absolute_paths")
 llvm.toolchain(
     name = "llvm_toolchain_with_system_llvm",
     llvm_versions = LLVM_VERSIONS,
-    cxx_standard = {"": "c++17"},
-)
-llvm.extra_target_compatible_with(
-    name = "llvm_toolchain_with_system_llvm",
-    constraints = ["@//:cxx17"],
 )
 # For this toolchain to work, the LLVM distribution archive would need to be unpacked here.
 llvm.toolchain_root(
@@ -173,11 +153,6 @@ use_repo(llvm, "llvm_toolchain_with_system_llvm")
 llvm.toolchain(
     name = "llvm_toolchain_with_sysroot",
     llvm_versions = LLVM_VERSIONS,
-    cxx_standard = {"": "c++17"},
-)
-llvm.extra_target_compatible_with(
-    name = "llvm_toolchain_with_sysroot",
-    constraints = ["@//:cxx17"],
 )
 # We can share the downloaded LLVM distribution with the first configuration.
 llvm.toolchain_root(
@@ -202,10 +177,5 @@ llvm.toolchain(
     # distribution = "clang+llvm-17.0.6-x86_64-linux-gnu-ubuntu-22.04.tar.xz",
     exec_os = "linux",
     exec_arch = "amd64",
-    cxx_standard = {"": "c++17"},
-)
-llvm.extra_target_compatible_with(
-    name = "llvm_toolchain_linux_exec",
-    constraints = ["@//:cxx17"],
 )
 use_repo(llvm, "llvm_toolchain_linux_exec")
diff --git a/tests/WORKSPACE b/tests/WORKSPACE
index f2a8af6f..65c8ee52 100644
--- a/tests/WORKSPACE
+++ b/tests/WORKSPACE
@@ -57,10 +57,6 @@ llvm_toolchain(
 # TODO(siddharthab): Add test.
 llvm_toolchain(
     name = "llvm_toolchain_with_urls",
-    cxx_standard = {"": "c++17"},
-    extra_target_compatible_with = {
-        "": ["@//:cxx17"],
-    },
     llvm_versions = LLVM_VERSIONS,
     sha256 = {
         "": "38bc7f5563642e73e69ac5626724e206d6d539fbef653541b34cae0ba9c3f036",
@@ -85,10 +81,6 @@ llvm_toolchain(
 # image base-devel as of the time of this writing (23 May 2022).
 llvm_toolchain(
     name = "llvm_toolchain_13_0_0",
-    cxx_standard = {"": "c++17"},
-    extra_target_compatible_with = {
-        "": ["@//:cxx17"],
-    },
     llvm_version = "13.0.0",
 )
 
@@ -104,10 +96,6 @@ llvm_register_toolchains_cxx20()
 llvm_toolchain(
     name = "llvm_toolchain_with_absolute_paths",
     absolute_paths = True,
-    cxx_standard = {"": "c++17"},
-    extra_target_compatible_with = {
-        "": ["@//:cxx17"],
-    },
     llvm_versions = LLVM_VERSIONS,
     # We can share the downloaded LLVM distribution with the first configuration.
     toolchain_roots = {
@@ -118,10 +106,6 @@ llvm_toolchain(
 ## Toolchain example with system LLVM; tested in GitHub CI.
 llvm_toolchain(
     name = "llvm_toolchain_with_system_llvm",
-    cxx_standard = {"": "c++17"},
-    extra_target_compatible_with = {
-        "": ["@//:cxx17"],
-    },
     llvm_versions = LLVM_VERSIONS,
     # For this toolchain to work, the LLVM distribution archive would need to be unpacked here.
     toolchain_roots = {"": "/opt/llvm-16"},
@@ -145,10 +129,6 @@ filegroup(
 
 llvm_toolchain(
     name = "llvm_toolchain_with_sysroot",
-    cxx_standard = {"": "c++17"},
-    extra_target_compatible_with = {
-        "": ["@//:cxx17"],
-    },
     llvm_versions = LLVM_VERSIONS,
     sysroot = {
         "linux-x86_64": "@org_chromium_sysroot_linux_x64//:sysroot",
@@ -165,14 +145,10 @@ bazel_skylib_workspace()
 
 llvm_toolchain(
     name = "llvm_toolchain_linux_exec",
-    cxx_standard = {"": "c++17"},
     exec_arch = "amd64",
     # Option 2:
     # distribution = "clang+llvm-17.0.6-x86_64-linux-gnu-ubuntu-22.04.tar.xz",
     exec_os = "linux",
-    extra_target_compatible_with = {
-        "": ["@//:cxx17"],
-    },
     llvm_version = "17.0.6",
     # Option 1:
     sha256 = {"": "884ee67d647d77e58740c1e645649e29ae9e8a6fe87c1376be0f3a30f3cc9ab3"},
diff --git a/tests/scripts/run_tests.sh b/tests/scripts/run_tests.sh
index 694e5533..c50a346a 100755
--- a/tests/scripts/run_tests.sh
+++ b/tests/scripts/run_tests.sh
@@ -46,8 +46,18 @@ test_args=(
   "--linkopt=-Wl,-t"
 )
 
+targets=(
+  "//:all"
+)
+# :test_cxx_standard_is_20 builds with a version of the default toolchain, if
+# we're trying to build with a different toolchain then it's likely the default
+# toolchain won't work so :test_cxx_standard_is_20 won't build.
+if [[ -z ${toolchain_name} ]]; then
+  targets+=("//:test_cxx_standard_is_20")
+fi
+
 "${bazel}" ${TEST_MIGRATION:+"--strict"} --bazelrc=/dev/null test \
-  "${common_test_args[@]}" "${test_args[@]}" //:all
+  "${common_test_args[@]}" "${test_args[@]}" "${targets[@]}"
 
 # Note that the following flags are currently known to cause issues in migration tests:
 # --incompatible_disallow_struct_provider_syntax # https://github.com/bazelbuild/bazel/issues/7347