Fix VS clang-cl build

* Disable "undefined-var-template" in code, rather than in build files
* Add back some missing headers required when building in this context
* Make sure gtest/gmock do not override the default runtime library

Change-Id: I12c05943fc1d2dee4733ae70db7da026f67e0dad
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/44180
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Antonio Maiorano <amaiorano@google.com>

src/castable.h

diff --git a/src/castable.h b/src/castable.h
index c5d88c3..956f4f6 100644
--- a/src/castable.h
+++ b/src/castable.h
@@ -17,6 +17,26 @@
 
 #include <utility>
 
+#if defined(__clang__)
+/// Temporarily disable certain warnings when using Castable API
+#define TINT_CASTABLE_PUSH_DISABLE_WARNINGS()                               \
+  _Pragma("clang diagnostic push")                                     /**/ \
+      _Pragma("clang diagnostic ignored \"-Wundefined-var-template\"") /**/ \
+      static_assert(true, "require extra semicolon")
+
+/// Restore disabled warnings
+#define TINT_CASTABLE_POP_DISABLE_WARNINGS() \
+  _Pragma("clang diagnostic pop") /**/       \
+      static_assert(true, "require extra semicolon")
+#else
+#define TINT_CASTABLE_PUSH_DISABLE_WARNINGS() \
+  static_assert(true, "require extra semicolon")
+#define TINT_CASTABLE_POP_DISABLE_WARNINGS() \
+  static_assert(true, "require extra semicolon")
+#endif
+
+TINT_CASTABLE_PUSH_DISABLE_WARNINGS();
+
 namespace tint {
 
 namespace detail {
@@ -25,11 +45,14 @@
 }  // namespace detail
 
 /// Helper macro to instantiate the TypeInfo<T> template for `CLASS`.
-#define TINT_INSTANTIATE_TYPEINFO(CLASS)                       \
-  template <>                                                  \
-  const tint::TypeInfo tint::detail::TypeInfoOf<CLASS>::info { \
-    &tint::detail::TypeInfoOf<CLASS::TrueBase>::info, #CLASS,  \
-  }
+#define TINT_INSTANTIATE_TYPEINFO(CLASS)                      \
+  TINT_CASTABLE_PUSH_DISABLE_WARNINGS();                      \
+  template <>                                                 \
+  const tint::TypeInfo tint::detail::TypeInfoOf<CLASS>::info{ \
+      &tint::detail::TypeInfoOf<CLASS::TrueBase>::info,       \
+      #CLASS,                                                 \
+  };                                                          \
+  TINT_CASTABLE_POP_DISABLE_WARNINGS()
 
 /// TypeInfo holds type information for a Castable type.
 struct TypeInfo {
@@ -197,4 +220,6 @@
 
 }  // namespace tint
 
+TINT_CASTABLE_POP_DISABLE_WARNINGS();
+
 #endif  // SRC_CASTABLE_H_

src/reader/spirv/parser_impl.cc

diff --git a/src/reader/spirv/parser_impl.cc b/src/reader/spirv/parser_impl.cc
index 729e33d..b694b6d 100644
--- a/src/reader/spirv/parser_impl.cc
+++ b/src/reader/spirv/parser_impl.cc
@@ -15,6 +15,7 @@
 #include "src/reader/spirv/parser_impl.h"
 
 #include <limits>
+#include <locale>
 
 #include "source/opt/build_module.h"
 #include "src/ast/bitcast_expression.h"

src/source.h

diff --git a/src/source.h b/src/source.h
index f56953c..416a30e 100644
--- a/src/source.h
+++ b/src/source.h
@@ -16,6 +16,7 @@
 #ifndef SRC_SOURCE_H_
 #define SRC_SOURCE_H_
 
+#include <iostream>
 #include <string>
 #include <vector>
 

third_party/CMakeLists.txt

diff --git a/third_party/CMakeLists.txt b/third_party/CMakeLists.txt
index b14613c..734ebca 100644
--- a/third_party/CMakeLists.txt
+++ b/third_party/CMakeLists.txt
@@ -13,6 +13,7 @@
 # limitations under the License.
 
 if (${TINT_BUILD_TESTS} AND NOT TARGET gmock)
+  set(gtest_force_shared_crt ON CACHE BOOL "" FORCE)
   add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/googletest EXCLUDE_FROM_ALL)
 endif()