1 files changed, 30 insertions, 17 deletions

diff --git a/chromium/build/config/win/BUILD.gn b/chromium/build/config/win/BUILD.gn
index 80bfa75f2e1..1f6bc13e087 100644
--- a/chromium/build/config/win/BUILD.gn
+++ b/chromium/build/config/win/BUILD.gn
@@ -3,6 +3,7 @@
 # found in the LICENSE file.
 
 import("//build/config/chrome_build.gni")
+import("//build/config/c++/c++.gni")
 import("//build/config/clang/clang.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/sanitizers/sanitizers.gni")
@@ -61,8 +62,6 @@ config("compiler") {
     "/Zc:sizedDealloc-",
   ]
 
-  # Building with Clang on Windows is a work in progress and very
-  # experimental. See crbug.com/82385.
   if (is_clang) {
     cflags += [ "-fmsc-version=1911" ]
 
@@ -85,6 +84,14 @@ config("compiler") {
     lib_dirs = [ "$clang_base_path/lib/clang/$clang_version/lib/windows" ]
   }
 
+  if (use_lld) {
+    # /Brepro lets the compiler not write the mtime field in the .obj output.
+    # link.exe /incremental relies on this field to work correctly, but lld
+    # never looks at this timestamp, so it's safe to pass this flag with
+    # lld and get more deterministic compiler output in return.
+    cflags += [ "/Brepro" ]
+  }
+
   # /PROFILE ensures that the PDB file contains FIXUP information (growing the
   # PDB file by about 5%) but does not otherwise alter the output binary. This
   # information is used by the Syzygy optimization tool when decomposing the
@@ -217,13 +224,26 @@ config("runtime_library") {
     # However it is prohibited when using /analyze
     defines += [ "_USING_V110_SDK71_" ]
   }
+
+  if (use_custom_libcxx) {
+    cflags_cc = [ "-I" + rebase_path("$libcxx_prefix/include", root_build_dir) ]
+    if (libcpp_is_static) {
+      defines += [ "_LIBCPP_DISABLE_VISIBILITY_ANNOTATIONS" ]
+    }
+
+    # Prevent libc++ from embedding linker flags to try to automatically link
+    # against its runtime library. This is unnecessary with our build system,
+    # and can also result in build failures if libc++'s name for a library does
+    # not match ours.
+    defines += [ "_LIBCPP_NO_AUTO_LINK" ]
+  }
 }
 
 # Sets the default Windows build version. This is separated because some
 # targets need to manually override it for their compiles.
 config("winver") {
   defines = [
-    "NTDDI_VERSION=0x0A000000",
+    "NTDDI_VERSION=0x0A000002",
     "_WIN32_WINNT=0x0A00",
     "WINVER=0x0A00",
   ]
@@ -262,20 +282,9 @@ config("common_linker_setup") {
     "/ignore:4199",
     "/ignore:4221",
     "/NXCOMPAT",
+    "/DYNAMICBASE",
   ]
 
-  # ASLR makes debugging with windbg difficult because Chrome.exe and
-  # Chrome.dll share the same base name. As result, windbg will name the
-  # Chrome.dll module like chrome_<base address>, where <base address>
-  # typically changes with each launch. This in turn means that breakpoints in
-  # Chrome.dll don't stick from one launch to the next. For this reason, we
-  # turn ASLR off in debug builds.
-  if (is_debug) {
-    ldflags += [ "/DYNAMICBASE:NO" ]
-  } else {
-    ldflags += [ "/DYNAMICBASE" ]
-  }
-
   if (win_linker_timing) {
     ldflags += [
       "/time",
@@ -289,8 +298,9 @@ config("cfi_linker") {
   # https://msdn.microsoft.com/en-us/library/windows/desktop/mt637065.aspx
   # /DYNAMICBASE (ASLR) is turned off in debug builds, therefore CFG can’t be
   # turned on either.
-  # TODO(thakis): Turn this on with lld once supported, https://crbug.com/693709
-  if (!is_debug && !use_lld) {
+  # CFG seems to lead to random corruption with incremental linking so turn off
+  # CFG in component builds. https://crbug.com/812421
+  if (!is_debug && !is_component_build) {
     # Turn on CFG in msvc linker, regardless of compiler used. Turn off CFG for
     # longjmp (new in VS 2017) because it relies on compiler support which we do
     # not have enabled.
@@ -373,6 +383,9 @@ config("windowed") {
 
 incremental_linking_on_switch = [ "/INCREMENTAL" ]
 incremental_linking_off_switch = [ "/INCREMENTAL:NO" ]
+if (use_lld) {
+  incremental_linking_on_switch += [ "/OPT:NOREF" ]
+}
 
 # Disable incremental linking for syzyasan, enable for debug builds and all
 # component builds - any builds where performance is not job one.