Update to bazel 8.0.0 (#4729)

This updates to bazel 8.0.0, also updating bazel mod deps and tools to
make that function. The release is a couple weeks old, and we haven't
updated in a while, and it's a major release. Note it includes some
incompatible flag flips that this is trying to update with respect to.
I'll try generally enabling incompatible support separately.

The most visible bazel behavior change here will be the change from `~`
to `+` in repo path names. (If you're curious,
bazelbuild/bazel#23127 indicates this fixes a
Windows performance issue)

Note that this is building on top of both the action env update in #4728
(which got me started down this path) and the proto removal in #4731
(which would add significant work to this update). Only the commit
starting at "Work towards bazel 8.0.0" is specifically part of this PR.

.bazelignore

@@ -7,3 +7,6 @@ bazel-carbon-lang
 
 # See github_tools/MODULE.bazel.
 github_tools
+
+# Used as part of repo patching.
+third_party/boost_unordered

.bazelrc

@@ -128,7 +128,18 @@ build --allow_unresolved_symlinks=false
 # RC file here if present.
 try-import %workspace%/user.bazelrc
 
+# TODO: WORKSPACE will be removed in bazel 9, should finish moving off.
+common --enable_workspace
+
+# The version of treesitter rules we're using depends on empty globs.
+# TODO: Look at the different rules in the registry.
+common --incompatible_disallow_empty_glob=false
+
 # TODO: Enable as many incompatible flags as we can, per
 # https://bazel.build/release/backward-compatibility. To get the latest list,
 # using `bazelisk --migrate build //...` will help.
-build --incompatible_strict_action_env
+common --incompatible_strict_action_env
+
+# This excludes things like rules_android to reduce warnings.
+# TODO: Disable this completely.
+common --incompatible_autoload_externally=+@rules_java,+@rules_python,+@rules_shell

.bazelversion

@@ -1 +1 @@
-7.3.0
+8.0.0

.gdbinit

@@ -2,6 +2,6 @@
 # Exceptions. See /LICENSE for license information.
 # SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
-source external/_main~llvm_project~llvm-project/llvm/utils/gdb-scripts/prettyprinters.py
-source external/_main~llvm_project~llvm-project/libcxx/utils/gdb/libcxx/printers.py
+source external/+llvm_project+llvm-project/llvm/utils/gdb-scripts/prettyprinters.py
+source external/+llvm_project+llvm-project/libcxx/utils/gdb/libcxx/printers.py
 python register_libcxx_printer_loader()

.vscode/lldb_launch.json

@@ -9,7 +9,7 @@
       "args": ["--file_tests=${relativeFile}"],
       "debuggerRoot": "${workspaceFolder}",
       "initCommands": [
-        "command script import external/_main~llvm_project~llvm-project/llvm/utils/lldbDataFormatters.py",
+        "command script import external/+llvm_project+llvm-project/llvm/utils/lldbDataFormatters.py",
         "settings set target.source-map \".\" \"${workspaceFolder}\""
       ],
       "env": { "TEST_TMPDIR": "/tmp" }
@@ -28,7 +28,7 @@
       ],
       "debuggerRoot": "${workspaceFolder}",
       "initCommands": [
-        "command script import external/_main~llvm_project~llvm-project/llvm/utils/lldbDataFormatters.py",
+        "command script import external/+llvm_project+llvm-project/llvm/utils/lldbDataFormatters.py",
         "settings set target.source-map \".\" \"${workspaceFolder}\""
       ]
     }

MODULE.bazel

@@ -29,11 +29,11 @@ http_archive = use_repo_rule(
 )
 
 bazel_dep(name = "bazel_skylib", version = "1.7.1")
-bazel_dep(name = "rules_pkg", version = "0.10.1")
-bazel_dep(name = "abseil-cpp", version = "20240116.2")
-bazel_dep(name = "re2", version = "2024-06-01")
-bazel_dep(name = "googletest", version = "1.14.0.bcr.1")
-bazel_dep(name = "google_benchmark", version = "1.8.4")
+bazel_dep(name = "rules_pkg", version = "1.0.1")
+bazel_dep(name = "abseil-cpp", version = "20240722.0.bcr.2")
+bazel_dep(name = "re2", version = "2024-07-02.bcr.1")
+bazel_dep(name = "googletest", version = "1.15.2")
+bazel_dep(name = "google_benchmark", version = "1.8.5")
 
 # The registry only has an old version. We use that here to avoid a miss but
 # override it with a newer version.
@@ -60,15 +60,15 @@ archive_override(
 bazel_dep(name = "tcmalloc", version = "0.0.0-20240411-5ed309d", dev_dependency = True)
 git_override(
     module_name = "tcmalloc",
-    # HEAD as of 2024-07-14.
-    commit = "923df94c922e0cd2d0512c1662d374f63c2c0c96",
+    # HEAD as of 2024-12-20.
+    commit = "91765c11461a01579fcbdddf430a556b818818c4",
     remote = "https://github.com/google/tcmalloc.git",
 )
 
-bazel_dep(name = "rules_bison", version = "0.2.2")
-bazel_dep(name = "rules_flex", version = "0.2.1")
-bazel_dep(name = "rules_m4", version = "0.2.3")
-bazel_dep(name = "rules_cc", version = "0.0.9")
+bazel_dep(name = "rules_bison", version = "0.3")
+bazel_dep(name = "rules_flex", version = "0.3")
+bazel_dep(name = "rules_m4", version = "0.2.4")
+bazel_dep(name = "rules_cc", version = "0.1.0")
 
 bazel_dep(name = "bazel_clang_tidy", dev_dependency = True)
 git_override(
@@ -106,7 +106,7 @@ http_archive(
 
 # Required for llvm-project.
 bazel_dep(name = "platforms", version = "0.0.10")
-bazel_dep(name = "zlib", version = "1.3.1.bcr.3", repo_name = "llvm_zlib")
+bazel_dep(name = "zlib", version = "1.3.1.bcr.4", repo_name = "llvm_zlib")
 bazel_dep(name = "zstd", version = "1.5.6", repo_name = "llvm_zstd")
 
 ###############################################################################
@@ -143,7 +143,7 @@ use_repo(llvm_project, "llvm-project")
 # Python
 ###############################################################################
 
-bazel_dep(name = "rules_python", version = "0.33.1")
+bazel_dep(name = "rules_python", version = "1.0.0")
 
 python = use_extension("@rules_python//python/extensions:python.bzl", "python")
 python.toolchain(