Minor tidying-up of workspace-relative vs absolute labels.

The use of absolute labels in `load()` calls was a workaround for a
Bazel bug[0] that was fixed in 2018, before the Bazel v1.0 release.

Using either absolute or relative labels as appropriate makes it
easier to understand whether a given load is expected to happen in
the `@rules_m4` repository or in the root workspace.

[0] bazelbuild/bazel#3115

GitOrigin-RevId: 7e5120adf89230c32569c6d9eb281123f1d48b54

m4/BUILD

@@ -1,4 +1,4 @@
-load("@rules_m4//m4/internal:toolchain_alias.bzl", "m4_toolchain_alias")
+load("//m4/internal:toolchain_alias.bzl", "m4_toolchain_alias")
 
 filegroup(
     name = "bzl_srcs",

m4/internal/testutil_ext.bzl

@@ -16,8 +16,8 @@
 
 """Helpers for testing rules_m4 in a bzlmod-enabled workspace."""
 
-load("@rules_m4//m4/internal:versions.bzl", "VERSION_URLS")
-load("@rules_m4//m4/rules:m4_repository.bzl", "m4_repository")
+load("//m4/internal:versions.bzl", "VERSION_URLS")
+load("//m4/rules:m4_repository.bzl", "m4_repository")
 load(":testutil.bzl", "rules_m4_testutil")
 
 def _rules_m4_testutil_ext(_module_ctx):

m4/internal/toolchain_alias.bzl

@@ -17,7 +17,7 @@
 """Shim rule for using m4 in a genrule."""
 
 load(
-    "@rules_m4//m4:toolchain_type.bzl",
+    "//m4:toolchain_type.bzl",
     "M4_TOOLCHAIN_TYPE",
     "m4_toolchain",
 )

m4/internal/toolchain_info.bzl

@@ -16,7 +16,7 @@
 
 """Bazel toolchain for the m4 macro expander."""
 
-load("@rules_m4//m4:providers.bzl", "M4ToolchainInfo")
+load("//m4:providers.bzl", "M4ToolchainInfo")
 
 def _template_vars(toolchain):
     return platform_common.TemplateVariableInfo({

m4/m4.bzl

@@ -17,29 +17,29 @@
 """Bazel rules for the m4 macro expander."""
 
 load(
-    "@rules_m4//m4:providers.bzl",
+    "//m4:providers.bzl",
     _M4ToolchainInfo = "M4ToolchainInfo",
 )
 load(
-    "@rules_m4//m4:toolchain_type.bzl",
+    "//m4:toolchain_type.bzl",
     _M4_TOOLCHAIN_TYPE = "M4_TOOLCHAIN_TYPE",
     _m4_toolchain = "m4_toolchain",
 )
 load(
-    "@rules_m4//m4/internal:versions.bzl",
+    "//m4/internal:versions.bzl",
     "DEFAULT_VERSION",
     "check_version",
 )
 load(
-    "@rules_m4//m4/rules:m4.bzl",
+    "//m4/rules:m4.bzl",
     _m4 = "m4",
 )
 load(
-    "@rules_m4//m4/rules:m4_repository.bzl",
+    "//m4/rules:m4_repository.bzl",
     _m4_repository = "m4_repository",
 )
 load(
-    "@rules_m4//m4/rules:m4_toolchain_repository.bzl",
+    "//m4/rules:m4_toolchain_repository.bzl",
     _m4_toolchain_repository = "m4_toolchain_repository",
 )
 

m4/rules/m4.bzl

@@ -17,7 +17,7 @@
 """Definition of the `m4` build rule."""
 
 load(
-    "@rules_m4//m4:toolchain_type.bzl",
+    "//m4:toolchain_type.bzl",
     "M4_TOOLCHAIN_TYPE",
     "m4_toolchain",
 )
@@ -133,12 +133,12 @@ These will be added to the command args immediately before the source files.
         ),
         "_capture_stdout": attr.label(
             executable = True,
-            default = "@rules_m4//m4/internal:capture_stdout",
+            default = Label("//m4/internal:capture_stdout"),
             cfg = "host",
         ),
         "_deny_shell": attr.label(
             executable = True,
-            default = "@rules_m4//m4/internal:deny_shell",
+            default = Label("//m4/internal:deny_shell"),
             cfg = "host",
         ),
     },

m4/rules/m4_repository.bzl

@@ -16,8 +16,8 @@
 
 """Definition of the `m4_repository` repository rule."""
 
-load("@rules_m4//m4/internal:versions.bzl", "VERSION_URLS")
-load("@rules_m4//m4/internal:gnulib/gnulib.bzl", "gnulib_overlay")
+load("//m4/internal:versions.bzl", "VERSION_URLS")
+load("//m4/internal:gnulib/gnulib.bzl", "gnulib_overlay")
 
 _M4_BUILD = """
 cc_library(
@@ -163,27 +163,27 @@ m4_repository(
             doc = "Additional C compiler options to use when building GNU M4.",
         ),
         "_gnulib_build": attr.label(
-            default = "@rules_m4//m4/internal:gnulib/gnulib.BUILD",
+            default = Label("//m4/internal:gnulib/gnulib.BUILD"),
             allow_single_file = True,
         ),
         "_gnulib_config_darwin_h": attr.label(
-            default = "//m4/internal:gnulib/config-darwin.h",
+            default = Label("//m4/internal:gnulib/config-darwin.h"),
             allow_single_file = True,
         ),
         "_gnulib_config_linux_h": attr.label(
-            default = "//m4/internal:gnulib/config-linux.h",
+            default = Label("//m4/internal:gnulib/config-linux.h"),
             allow_single_file = True,
         ),
         "_gnulib_config_windows_h": attr.label(
-            default = "//m4/internal:gnulib/config-windows.h",
+            default = Label("//m4/internal:gnulib/config-windows.h"),
             allow_single_file = True,
         ),
         "_gnulib_config_openbsd_h": attr.label(
-            default = "//m4/internal:gnulib/config-openbsd.h",
+            default = Label("//m4/internal:gnulib/config-openbsd.h"),
             allow_single_file = True,
         ),
         "_gnulib_config_freebsd_h": attr.label(
-            default = "//m4/internal:gnulib/config-freebsd.h",
+            default = Label("//m4/internal:gnulib/config-freebsd.h"),
             allow_single_file = True,
         ),
     },

m4/toolchains/BUILD

@@ -1,5 +1,5 @@
-load("@rules_m4//m4:toolchain_type.bzl", "M4_TOOLCHAIN_TYPE")
-load("@rules_m4//m4/internal:versions.bzl", "VERSION_URLS")
+load("//m4:toolchain_type.bzl", "M4_TOOLCHAIN_TYPE")
+load("//m4/internal:versions.bzl", "VERSION_URLS")
 
 [toolchain(
     name = "v{}".format(version),

tests/BUILD

@@ -1,4 +1,4 @@
-load("@rules_m4//m4:m4.bzl", "m4")
+load("//m4:m4.bzl", "m4")
 
 m4(
     name = "expansion_test",
@@ -15,7 +15,7 @@ genrule(
 cp $(location expansion_test.in) genrule_test.in
 $(M4) --synclines genrule_test.in > $@
 """,
-    toolchains = ["@rules_m4//m4:current_m4_toolchain"],
+    toolchains = ["//m4:current_m4_toolchain"],
 )
 
 m4(