Fetch fp16 dependency of v8, and patch v8 to find it

Signed-off-by: Michael Warres <[email protected]>

bazel/external/v8.patch

@@ -3,9 +3,11 @@
 # 3. Revert v8 commit b26554ec368e9553782012c96aa5e99b163eaff2, which removed
 #    use of _allowlist_function_transition from v8 bazel/defs.bzl, since it is
 #    still required by the version of Bazel we currently use (6.5.0).
+# 4. Tweak where v8 looks for its fp16 dependency, since it isn't downloaded by
+#    gn.
 
 diff --git a/BUILD.bazel b/BUILD.bazel
-index 30be47fa333..d03d1e4d522 100644
+index 30be47fa333..093599d47df 100644
 --- a/BUILD.bazel
 +++ b/BUILD.bazel
 @@ -220,7 +220,7 @@ v8_int(
@@ -17,6 +19,25 @@ index 30be47fa333..d03d1e4d522 100644
  )
 
  # Default setting for v8_enable_pointer_compression.
+@@ -3698,13 +3698,14 @@ filegroup(
+
+ v8_library(
+   name = "lib_fp16",
+-  srcs = ["third_party/fp16/src/include/fp16.h"],
++  srcs = ["@fp16//:include/fp16.h"],
+   hdrs = [
+-    "third_party/fp16/src/include/fp16/fp16.h",
+-    "third_party/fp16/src/include/fp16/bitcasts.h",
++    "@fp16//:include/fp16/fp16.h",
++    "@fp16//:include/fp16/bitcasts.h",
+   ],
++  include_prefix = "third_party/fp16/src",
+   includes = [
+-    "third_party/fp16/src/include",
++    "@fp16//:include",
+   ],
+ )
+
 diff --git a/bazel/defs.bzl b/bazel/defs.bzl
 index 520a311595e..246c4ecf27a 100644
 --- a/bazel/defs.bzl

bazel/repositories.bzl

@@ -196,6 +196,14 @@ def proxy_wasm_cpp_host_repositories():
         actual = "@com_google_absl//absl/container:flat_hash_set",
     )
 
+    maybe(
+        git_repository,
+        name = "fp16",
+        commit = "0a92994d729ff76a58f692d3028ca1b64b145d91",
+        build_file_content = "exports_files(glob([\"**\"]))",
+        remote = "https://chromium.googlesource.com/external/github.com/Maratyszcza/FP16.git",
+    )
+
     # WAMR with dependencies.
 
     maybe(