Roll clang 278861:280106.

* win: Members of base classes now should show up in debugger.
* win: Debugger shouldn't show funny highlights anymore due to
  debug info no longer including column information.  (we still
  force this on if sanitizers are used, mostly for clusterfuzz.
  maybe we want to make this toggleable independent of sanitizers
  at some point)
* win: -Wextern-initializer no longer warns on midl-generated code
* win: clang-cl now accepts /source-encoding:utf-8 and friends
  (utf-8 was the source enconding in clang-cl before already, but
  now we don't warn on an explicit flag requesting this)
* all platforms: Three plugin checks are now on-by-default,
  remove flags for these (see
    https://codereview.chromium.org/2267713003
    https://codereview.chromium.org/2268203002
    https://codereview.chromium.org/2265093002
  )
* win: clang-cl's /Brepro now does what it's supposed to do
* win: clang-cl now emits absolute paths in diagnostics, by
  popular request.

Ran `tools/clang/scripts/upload_revision.py 280106`.

BUG=640254,637456,636109,636091,636099

Review-Url: https://codereview.chromium.org/2292173002
Cr-Commit-Position: refs/heads/master@{#415563}

build/config/clang/BUILD.gn

@@ -35,18 +35,6 @@ config("find_bad_constructs") {
       "-add-plugin",
       "-Xclang",
       "find-bad-constructs",
-      "-Xclang",
-      "-plugin-arg-find-bad-constructs",
-      "-Xclang",
-      "check-templates",
-      "-Xclang",
-      "-plugin-arg-find-bad-constructs",
-      "-Xclang",
-      "follow-macro-expansion",
-      "-Xclang",
-      "-plugin-arg-find-bad-constructs",
-      "-Xclang",
-      "enforce-in-pdf",
     ]
 
     if ((is_linux || is_android) && !is_chromecast) {

build/config/compiler/BUILD.gn

@@ -374,8 +374,7 @@ config("compiler") {
   # Print absolute paths in diagnostics. There is no precedent for doing this
   # on Linux/Mac (GCC doesn't support it), but MSVC does this with /FC and
   # Windows developers rely on it (crbug.com/636109) so only do this on Windows.
-  # TODO(hans) Remove llvm_force_head_revision check in next clang roll.
-  if (is_clang && is_win && llvm_force_head_revision) {
+  if (is_clang && is_win) {
     cflags += [ "-fdiagnostics-absolute-paths" ]
   }
 

build/config/sanitizers/BUILD.gn

@@ -231,7 +231,14 @@ config("common_sanitizer_flags") {
   # or variable info, so we can leave that out to speed up the build.
   if (using_sanitizer) {
     assert(is_clang, "sanitizers only supported with clang")
-    cflags += [ "-gline-tables-only" ]
+    cflags += [
+      "-gline-tables-only",
+
+      # Column info in debug data confuses Visual Studio's debugger, so don't
+      # use this by default.  However, clusterfuzz needs it for good attribution
+      # of reports to CLs, so turn it on there.
+      "-gcolumn-info",
+    ]
   }
 
   # Common options for AddressSanitizer, LeakSanitizer, ThreadSanitizer,

build/config/win/BUILD.gn

@@ -402,13 +402,7 @@ config("target_winrt") {
 # Config used by the MIDL template to disable warnings.
 config("midl_warnings") {
   if (is_clang) {
-    cflags = [
-      # MIDL generates code like "#endif !_MIDL_USE_GUIDDEF_".
-      "-Wno-extra-tokens",
-
-      # TODO(thakis): Remove this once clang is rolled past r279116,
-      # https://crbug.com/637456
-      "-Wno-extern-initializer",
-    ]
+    # MIDL generates code like "#endif !_MIDL_USE_GUIDDEF_".
+    cflags = [ "-Wno-extra-tokens" ]
   }
 }

tools/clang/scripts/update.py

@@ -27,7 +27,7 @@ import zipfile
 # Do NOT CHANGE this if you don't know what you're doing -- see
 # https://chromium.googlesource.com/chromium/src/+/master/docs/updating_clang.md
 # Reverting problematic clang rolls is safe, though.
-CLANG_REVISION = '278861'
+CLANG_REVISION = '280106'
 
 use_head_revision = 'LLVM_FORCE_HEAD_REVISION' in os.environ
 if use_head_revision: