rename main() entrypoints to main.go (#1901)

Based on https://go.dev/doc/modules/layout#basic-command

The file with the `main()` function should be named `main.go`. 

This makes things easier to find while searching through source code.

cmd/autogazelle/BUILD.bazel

@@ -3,8 +3,8 @@ load("@io_bazel_rules_go//go:def.bzl", "go_binary", "go_library")
 go_library(
     name = "autogazelle_lib",
     srcs = [
-        "autogazelle.go",
         "client_unix.go",
+        "main.go",
         "server_unix.go",
     ],
     importpath = "github.com/bazelbuild/bazel-gazelle/cmd/autogazelle",
@@ -57,8 +57,8 @@ filegroup(
         "BUILD.bazel",
         "README.rst",
         "autogazelle.bash",
-        "autogazelle.go",
         "client_unix.go",
+        "main.go",
         "server_unix.go",
     ],
     visibility = ["//visibility:public"],

cmd/fetch_repo/BUILD.bazel

@@ -6,8 +6,8 @@ go_library(
         "clean.go",
         "copy_tree.go",
         "errorscompat.go",
-        "fetch_repo.go",
         "go_mod_download.go",
+        "main.go",
         "module.go",
         "path.go",
         "vcs.go",
@@ -34,8 +34,8 @@ go_cross_binary(
 )
 
 go_test(
-    name = "fetch_repo_test",
-    srcs = ["fetch_repo_test.go"],
+    name = "main_test",
+    srcs = ["main_test.go"],
     embed = [":fetch_repo_lib"],
     deps = ["@org_golang_x_tools_go_vcs//:vcs"],
 )
@@ -48,12 +48,19 @@ filegroup(
         "clean.go",
         "copy_tree.go",
         "errorscompat.go",
-        "fetch_repo.go",
-        "fetch_repo_test.go",
         "go_mod_download.go",
+        "main.go",
+        "main_test.go",
         "module.go",
         "path.go",
         "vcs.go",
     ],
     visibility = ["//visibility:public"],
 )
+
+go_test(
+    name = "fetch_repo_test",
+    srcs = ["main_test.go"],
+    embed = [":fetch_repo_lib"],
+    deps = ["@org_golang_x_tools_go_vcs//:vcs"],
+)

cmd/gazelle/BUILD.bazel

@@ -14,7 +14,7 @@ go_library(
         "diff.go",
         "fix.go",
         "fix-update.go",
-        "gazelle.go",
+        "main.go",
         "metaresolver.go",
         "print.go",
         "profiler.go",
@@ -73,9 +73,9 @@ filegroup(
         "fix.go",
         "fix-update.go",
         "fix_test.go",
-        "gazelle.go",
         "integration_test.go",
         "langs.go",
+        "main.go",
         "metaresolver.go",
         "print.go",
         "profiler.go",

cmd/generate_repo_config/BUILD.bazel

@@ -2,7 +2,7 @@ load("@io_bazel_rules_go//go:def.bzl", "go_binary", "go_library", "go_test")
 
 go_library(
     name = "generate_repo_config_lib",
-    srcs = ["generate_repo_config.go"],
+    srcs = ["main.go"],
     importpath = "github.com/bazelbuild/bazel-gazelle/cmd/generate_repo_config",
     visibility = ["//visibility:private"],
     deps = [
@@ -19,7 +19,7 @@ go_binary(
 
 go_test(
     name = "generate_repo_config_test",
-    srcs = ["generate_repo_config_test.go"],
+    srcs = ["main_test.go"],
     embed = [":generate_repo_config_lib"],
     deps = ["//testtools"],
 )
@@ -29,8 +29,8 @@ filegroup(
     testonly = True,
     srcs = [
         "BUILD.bazel",
-        "generate_repo_config.go",
-        "generate_repo_config_test.go",
+        "main.go",
+        "main_test.go",
     ],
     visibility = ["//visibility:public"],
 )

cmd/move_labels/BUILD.bazel

@@ -2,7 +2,7 @@ load("@io_bazel_rules_go//go:def.bzl", "go_binary", "go_library", "go_test")
 
 go_library(
     name = "move_labels_lib",
-    srcs = ["move_labels.go"],
+    srcs = ["main.go"],
     importpath = "github.com/bazelbuild/bazel-gazelle/cmd/move_labels",
     visibility = ["//visibility:private"],
     deps = [
@@ -21,7 +21,7 @@ go_binary(
 
 go_test(
     name = "move_labels_test",
-    srcs = ["move_labels_test.go"],
+    srcs = ["main_test.go"],
     embed = [":move_labels_lib"],
     deps = ["//testtools"],
 )
@@ -31,8 +31,8 @@ filegroup(
     testonly = True,
     srcs = [
         "BUILD.bazel",
-        "move_labels.go",
-        "move_labels_test.go",
+        "main.go",
+        "main_test.go",
     ],
     visibility = ["//visibility:public"],
 )

internal/go_repository_tools_srcs.bzl

@@ -4,32 +4,32 @@ GO_REPOSITORY_TOOLS_SRCS = [
     Label("//:BUILD.bazel"),
     Label("//cmd:BUILD.bazel"),
     Label("//cmd/autogazelle:BUILD.bazel"),
-    Label("//cmd/autogazelle:autogazelle.go"),
     Label("//cmd/autogazelle:client_unix.go"),
+    Label("//cmd/autogazelle:main.go"),
     Label("//cmd/autogazelle:server_unix.go"),
     Label("//cmd/fetch_repo:BUILD.bazel"),
     Label("//cmd/fetch_repo:clean.go"),
     Label("//cmd/fetch_repo:copy_tree.go"),
     Label("//cmd/fetch_repo:errorscompat.go"),
-    Label("//cmd/fetch_repo:fetch_repo.go"),
     Label("//cmd/fetch_repo:go_mod_download.go"),
+    Label("//cmd/fetch_repo:main.go"),
     Label("//cmd/fetch_repo:module.go"),
     Label("//cmd/fetch_repo:path.go"),
     Label("//cmd/fetch_repo:vcs.go"),
     Label("//cmd/gazelle:BUILD.bazel"),
     Label("//cmd/gazelle:diff.go"),
     Label("//cmd/gazelle:fix-update.go"),
     Label("//cmd/gazelle:fix.go"),
-    Label("//cmd/gazelle:gazelle.go"),
     Label("//cmd/gazelle:langs.go"),
+    Label("//cmd/gazelle:main.go"),
     Label("//cmd/gazelle:metaresolver.go"),
     Label("//cmd/gazelle:print.go"),
     Label("//cmd/gazelle:profiler.go"),
     Label("//cmd/gazelle:update-repos.go"),
     Label("//cmd/generate_repo_config:BUILD.bazel"),
-    Label("//cmd/generate_repo_config:generate_repo_config.go"),
+    Label("//cmd/generate_repo_config:main.go"),
     Label("//cmd/move_labels:BUILD.bazel"),
-    Label("//cmd/move_labels:move_labels.go"),
+    Label("//cmd/move_labels:main.go"),
     Label("//config:BUILD.bazel"),
     Label("//config:config.go"),
     Label("//config:constants.go"),