Revert "build: workaround for VC v14.25 / MSVC 19.25"

This reverts commit 6c92556c.

Reason for revert: Visual Studio 16.5.2 released, which fixes the issue,
and the workaround is (ironically) incompatible with 16.5.2.

Original change's description:
> build: workaround for VC v14.25 / MSVC 19.25
>
> Adds a temporary fix to vs_toolchain.py to use the previous version of
> MSVC's header files and documents how to install the previous version
> alongside 19.25.
>
> Bug: 1058860
> Change-Id: I6e96af3c71b23e5c5430237d00125a5830c37855
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2117732
> Commit-Queue: Richard Townsend <richard.townsend@arm.com>
> Reviewed-by: Nico Weber <thakis@chromium.org>
> Reviewed-by: Scott Violet <sky@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#753998}

TBR=sky@chromium.org,thakis@chromium.org,richard.townsend@arm.com

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 1058860,1066935
Change-Id: I343aac7a0af7d89bf5497bf0d063e03731599f9e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2132379Reviewed-by: Bruce Dawson <brucedawson@chromium.org>
Commit-Queue: Richard Townsend <richard.townsend@arm.com>
Cr-Commit-Position: refs/heads/master@{#755490}

build/toolchain/win/setup_toolchain.py

@@ -158,11 +158,6 @@ def _LoadToolchainEnv(cpu, sdk_dir, target_store):
     if (target_store):
       args.append(['store'])
     variables = _LoadEnvFromBat(args)
-    # Check for faulty 14.25 version of system headers (see crbug.com/1058860).
-    if "14.25" in _ExtractImportantEnvironment(variables)["LIB"]:
-      # If detected, switch back to 14.24.
-      args.append(["-vcvars_ver=14.24"])
-      variables = _LoadEnvFromBat(args)
   return _ExtractImportantEnvironment(variables)
 
 

build/vs_toolchain.py

@@ -320,21 +320,11 @@ def FindVCComponentRoot(component):
   vc_component_msvc_contents = os.listdir(vc_component_msvc_root)
   # Select the most recent toolchain if there are several.
   _SortByHighestVersionNumberFirst(vc_component_msvc_contents)
-  acceptable_msvc_version_found = False
   for directory in vc_component_msvc_contents:
-    if directory.startswith('14.25'):
-      print(
-          "Warning: known issue affecting the headers distributed with VC version {}."
-          .format(directory))
-      print("See https://crbug.com/1063424 for details.")
-      continue
-    acceptable_msvc_version_found = True
     if not os.path.isdir(os.path.join(vc_component_msvc_root, directory)):
       continue
     if re.match(r'14\.\d+\.\d+', directory):
       return os.path.join(vc_component_msvc_root, directory)
-  if not acceptable_msvc_version_found:
-    raise Exception("Unable to find a suitable VC version.")
   raise Exception('Unable to find the VC %s directory.' % component)
 
 

docs/windows_build_instructions.md

@@ -61,22 +61,6 @@ Software Development Kit" → Change → Change → Check "Debugging Tools For
 Windows" → Change. Or, you can download the standalone SDK installer and use it
 to install the Debugging Tools.
 
-### Known issue with Visual Studio 16.5.0
-Visual Studio 16.5.0 includes some header files which are incompatible with the
-C++ standard used in Chromium (see [crbug.com/1063424](https://crbug.com/1063424)
-for details.) A workaround is to install the older command-line tools:
-```shell
-$ PATH_TO_INSTALLER.exe ^
-    --add "Microsoft.VisualStudio.Component.VC.14.24.ARM64" ^
-    --add "Microsoft.VisualStudio.Component.VC.14.24.x86.x64" ^
-    --add "Microsoft.VisualStudio.Component.VC.14.24.ATL.ARM64" ^
-    --add "Microsoft.VisualStudio.Component.VC.14.24.ATL" ^
-    --add "Microsoft.VisualStudio.Component.VC.14.24.MFC.ARM64" ^
-    --add "Microsoft.VisualStudio.Component.VC.14.24.MFC" ^
-    --includeRecommended
-```
-
-
 ## Install `depot_tools`
 
 Download the [depot_tools bundle](https://storage.googleapis.com/chrome-infra/depot_tools.zip)