Change rules_foreign_cc_dependencies so that by default the built

pkgconfig toolchain is not registered, as a few extra bazel flags are
required on Windows.

.bazelci/config.yaml

@@ -131,8 +131,6 @@ tasks:
       - "-//cmake_with_data/..."
     build_targets: *windows_targets
     test_targets: *windows_targets
-    test_flags:
-      - "--enable_runfiles"
   rbe_ubuntu1604_flags:
     name: Flags
     platform: rbe_ubuntu1604

WORKSPACE.bazel

@@ -3,7 +3,7 @@ workspace(name = "rules_foreign_cc")
 load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
 load("//foreign_cc:repositories.bzl", "rules_foreign_cc_dependencies")
 
-rules_foreign_cc_dependencies()
+rules_foreign_cc_dependencies(register_built_pkgconfig_toolchain=True)
 
 local_repository(
     name = "rules_foreign_cc_examples",

examples/.bazelrc

@@ -0,0 +1,8 @@
+
+# Required for Windows
+build --enable_runfiles
+
+# These are required otherwise paths are too long
+startup --windows_enable_symlinks
+build --action_env=MSYS=winsymlinks:nativestrict
+test --action_env=MSYS=winsymlinks:nativestrict

examples/WORKSPACE.bazel

@@ -7,8 +7,7 @@ local_repository(
 
 load("@rules_foreign_cc//foreign_cc:repositories.bzl", "rules_foreign_cc_dependencies")
 
-# Don't use preinstalled tools to ensure builds are as hermetic as possible
-rules_foreign_cc_dependencies(register_preinstalled_tools = False)
+rules_foreign_cc_dependencies(register_built_pkgconfig_toolchain=True)
 
 load("@bazel_skylib//:workspace.bzl", "bazel_skylib_workspace")
 

examples/third_party/WORKSPACE.bazel

@@ -7,7 +7,7 @@ local_repository(
 
 load("@rules_foreign_cc//foreign_cc:repositories.bzl", "rules_foreign_cc_dependencies")
 
-rules_foreign_cc_dependencies()
+rules_foreign_cc_dependencies(register_built_pkgconfig_toolchain=True)
 
 local_repository(
     name = "rules_foreign_cc_examples",

foreign_cc/repositories.bzl

@@ -15,7 +15,8 @@ def rules_foreign_cc_dependencies(
         pkgconfig_version = "0.29.2",
         register_preinstalled_tools = True,
         register_built_tools = True,
-        register_toolchains = True):
+        register_toolchains = True,
+        register_built_pkgconfig_toolchain = False):
     """Call this function from the WORKSPACE file to initialize rules_foreign_cc \
     dependencies and let neccesary code generation happen \
     (Code generation is needed to support different variants of the C++ Starlark API.).
@@ -47,6 +48,14 @@ def rules_foreign_cc_dependencies(
         register_built_tools: If true, toolchains that build the tools from source are registered
 
         register_toolchains: If true, registers the toolchains via native.register_toolchains. Used by bzlmod
+
+        register_built_pkgconfig_toolchain: If true, the built pkgconfig toolchain will be registered. On Windows it may be preferrable to set this to False, as
+            this requires the --enable_runfiles bazel option. Also note that building pkgconfig from source under bazel results in paths that are more
+            than 256 characters long, which will not work on Windows unless the following options are added to the .bazelrc and symlinks are enabled in Windows.
+
+            startup --windows_enable_symlinks -> This is required to enable symlinking to avoid long runfile paths
+            build --action_env=MSYS=winsymlinks:nativestrict -> This is required to enable symlinking to avoid long runfile paths
+            startup --output_user_root=C:/b  -> This is required to keep paths as short as possible
     """
 
     register_framework_toolchains(register_toolchains = register_toolchains)
@@ -64,6 +73,7 @@ def rules_foreign_cc_dependencies(
             ninja_version = ninja_version,
             pkgconfig_version = pkgconfig_version,
             register_toolchains = register_toolchains,
+            register_built_pkgconfig_toolchain = register_built_pkgconfig_toolchain,
         )
 
     if register_preinstalled_tools:

foreign_cc/utils.bzl

@@ -22,12 +22,20 @@ def runnable_binary(name, binary, foreign_cc_target, match_binary_name = False,
 
     tags = kwargs.pop("tags", [])
 
+    # filegroups cannot select on constraint_values in before Bazel 5.1. Add this config_setting as a workaround. See https://github.com/bazelbuild/bazel/issues/13047
+    native.config_setting(
+        name = "windows_config_setting",
+        constraint_values = [
+            "@platforms//os:windows",
+        ],
+    )
+
     native.filegroup(
         name = name + "_fg",
         srcs = [foreign_cc_target],
         tags = tags + ["manual"],
         output_group = select({
-            "@platforms//os:windows": binary + ".exe",
+            ":windows_config_setting": binary + ".exe",
             "//conditions:default": binary,
         }),
     )

toolchains/built_toolchains.bzl

@@ -31,12 +31,14 @@ _CMAKE_SRCS = {
 }
 
 # buildifier: disable=unnamed-macro
-def built_toolchains(cmake_version, make_version, ninja_version, pkgconfig_version, register_toolchains):
+def built_toolchains(cmake_version, make_version, ninja_version, pkgconfig_version, register_toolchains, register_built_pkgconfig_toolchain):
     """Register toolchains for built tools that will be built from source"""
     _cmake_toolchain(cmake_version, register_toolchains)
     _make_toolchain(make_version, register_toolchains)
     _ninja_toolchain(ninja_version, register_toolchains)
-    _pkgconfig_toolchain(pkgconfig_version, register_toolchains)
+
+    if register_built_pkgconfig_toolchain:
+        _pkgconfig_toolchain(pkgconfig_version, register_toolchains)
 
 def _cmake_toolchain(version, register_toolchains):
     if register_toolchains: