Use include_bytes! instead of incbin.

This is the second attempt at this patch. The first version was reverted
in 2ffd78da

The problem, I suspect, was that the snapshot was represented as a
source_set, which inserted a node into the dependency tree.
include_bytes does properly insert the snapshot into rustc's depfile but
the use of source_set confused gn. Now the that the deno executable has
the create_deno_snapshot as a direct dependency, changes will be
propagated.

BUILD.gn

@@ -111,6 +111,14 @@ ts_sources = [
   "third_party/yarn.lock",
 ]
 
+group("deno_deps") {
+  deps = [
+    ":create_snapshot_deno",
+    ":msg_rs",
+    "libdeno:libdeno",
+  ]
+}
+
 rust_executable("deno") {
   source_root = "src/main.rs"
   extern = main_extern
@@ -119,41 +127,12 @@ rust_executable("deno") {
   ]
 }
 
-source_set("snapshot") {
-  sources = [
-    "src/snapshot.cc",
-  ]
-  configs += [ "libdeno:deno_config" ]
-  inputs = [
-    "$target_gen_dir/snapshot_deno.bin",
-  ]
+rust_test("test_rs") {
+  source_root = "src/main.rs"
+  extern = main_extern
   deps = [
-    ":create_snapshot_deno",
+    ":deno_deps",
   ]
-
-  # snapshot.cc doesn't need to depend on libdeno, it just needs deno_buf.
-  include_dirs = [ "libdeno/" ]
-
-  # src/snapshot.cc uses an assembly '.incbin' directive to embed the snapshot.
-  # This causes trouble when using sccache: since the snapshot file is not
-  # inlined by the c preprocessor, sccache doesn't take its contents into
-  # consideration, leading to false-positive cache hits.
-  # Maybe other caching tools have this issue too, but ccache is unaffected.
-  # Therefore, if a cc_wrapper is used that isn't ccache, include a generated
-  # header file that contains the the sha256 hash of the snapshot.
-  if (cc_wrapper != "" && cc_wrapper != "ccache") {
-    hash_h = "$target_gen_dir/bundle/hash.h"
-    inputs += [ hash_h ]
-    deps += [ ":bundle_hash_h" ]
-    if (is_win) {
-      cflags = [ "/FI" + rebase_path(hash_h, target_out_dir) ]
-    } else {
-      cflags = [
-        "-include",
-        rebase_path(hash_h, target_out_dir),
-      ]
-    }
-  }
 }
 
 rust_executable("hyper_hello") {
@@ -164,24 +143,6 @@ rust_executable("hyper_hello") {
   ]
 }
 
-rust_test("test_rs") {
-  source_root = "src/main.rs"
-  extern = main_extern
-  deps = [
-    ":deno_deps",
-  ]
-}
-
-v8_static_library("deno_deps") {
-  complete_static_lib = true
-  public_deps = [
-    ":msg_rs",
-    ":snapshot",
-    "libdeno:libdeno",
-  ]
-  configs = [ "libdeno:deno_config" ]
-}
-
 # Generates the core TypeScript type library for deno that will be
 # included in the runtime bundle
 run_node("deno_runtime_declaration") {
@@ -236,29 +197,6 @@ run_node("bundle") {
   ]
 }
 
-action("bundle_hash_h") {
-  script = "//tools/sha256sum.py"
-  inputs = get_target_outputs(":bundle")
-  outputs = [
-    "$target_gen_dir/bundle/hash.h",
-  ]
-  deps = [
-    ":bundle",
-  ]
-  args = [
-    "--format",
-    "__attribute__((__unused__)) static const int dummy_%s = 0;",
-    "--outfile",
-    rebase_path(outputs[0], root_build_dir),
-  ]
-  foreach(input, inputs) {
-    args += [
-      "--infile",
-      rebase_path(input, root_build_dir),
-    ]
-  }
-}
-
 ts_flatbuffer("msg_ts") {
   sources = [
     "src/msg.fbs",

src/main.rs

@@ -97,7 +97,7 @@ fn main() {
   });
 
   let state = Arc::new(isolate::IsolateState::new(flags, rest_argv));
-  let snapshot = unsafe { snapshot::deno_snapshot.clone() };
+  let snapshot = snapshot::deno_snapshot();
   let mut isolate = isolate::Isolate::new(snapshot, state, ops::dispatch);
   tokio_util::init(|| {
     isolate

src/snapshot.cc

-// Copyright 2018 the Deno authors. All rights reserved. MIT license.
-
-#include "deno.h"
-
-extern "C" {
-
-extern const char snapshot_start asm("snapshot_start");
-extern const char snapshot_end asm("snapshot_end");
-asm(".data\n"
-    "snapshot_start: .incbin \"gen/snapshot_deno.bin\"\n"
-    "snapshot_end:\n"
-    ".globl snapshot_start;\n"
-    ".globl snapshot_end;");
-extern const deno_buf deno_snapshot = {
-  nullptr, 0, reinterpret_cast<uint8_t*>(const_cast<char*>(&snapshot_start)),
-  static_cast<size_t>(&snapshot_end - &snapshot_start)};
-
-}

src/snapshot.rs

 // Copyright 2018 the Deno authors. All rights reserved. MIT license.
 use libdeno::deno_buf;
-extern "C" {
-  pub static deno_snapshot: deno_buf;
+use std;
+
+pub fn deno_snapshot() -> deno_buf {
+  let data =
+    include_bytes!(concat!(env!("GN_OUT_DIR"), "/gen/snapshot_deno.bin"));
+  let ptr = data.as_ptr();
+  // TODO The cast is not necessary here. deno_buf specifies mutable
+  // pointers when it doesn't necessarally need mutable. So maybe the deno_buf
+  // type should be broken into a mutable and non-mutable version?
+  let ptr_mut = ptr as *mut u8;
+  deno_buf {
+    alloc_ptr: std::ptr::null_mut(),
+    alloc_len: 0,
+    data_ptr: ptr_mut,
+    data_len: data.len(),
+  }
 }