Fix LLVM 7 issues with MSVC, enable FindClangTools.cmake to find clang-format in conda env

Author: wesm

cpp/cmake_modules/FindClangTools.cmake

@@ -53,8 +53,10 @@ set(CLANG_TOOLS_SEARCH_PATHS
   ${ClangTools_PATH}
   $ENV{CLANG_TOOLS_PATH}
   /usr/local/bin /usr/bin
-  "C:/Program Files/LLVM/bin"
-  "${HOMEBREW_PREFIX}/bin")
+  "C:/Program Files/LLVM/bin"  # Windows, non-conda
+  "$ENV{CONDA_PREFIX}/Library/bin"  # Windows, conda
+  "${HOMEBREW_PREFIX}/bin"
+)
 
 find_program(CLANG_TIDY_BIN
   NAMES clang-tidy-${ARROW_LLVM_VERSION}

cpp/src/gandiva/engine.cc

@@ -15,6 +15,12 @@
 // specific language governing permissions and limitations
 // under the License.
 
+// TODO(wesm): LLVM 7 produces pesky C4244 that disable pragmas around the LLVM
+// includes seem to not fix as with LLVM 6
+#if defined(_MSC_VER)
+#pragma warning(disable : 4244)
+#endif
+
 #include "gandiva/engine.h"
 
 #include <iostream>

cpp/src/gandiva/precompiled/time_test.cc

@@ -67,6 +67,15 @@ TEST(TestTime, TestCastTimestamp) {
             -1187308799080);
   EXPECT_EQ(castTIMESTAMP_utf8(context_ptr, "1857-02-11 20:31:40.920 -05:30", 30),
             -3562264699080);
+}
+
+#ifndef _WIN32
+
+// TODO(wesm): ARROW-4495. Need to address TZ database issues on Windows
+
+TEST(TestTime, TestCastTimestampWithTZ) {
+  ExecutionContext context;
+  int64_t context_ptr = reinterpret_cast<int64_t>(&context);
 
   EXPECT_EQ(castTIMESTAMP_utf8(context_ptr, "2000-09-23 9:45:30.920 Canada/Pacific", 37),
             969727530920);
@@ -76,10 +85,6 @@ TEST(TestTime, TestCastTimestamp) {
             -1459094217000);
 }
 
-#ifndef _WIN32
-
-// TODO(wesm): ARROW-4495. Fix these tests on Windows
-
 TEST(TestTime, TestCastTimestampErrors) {
   ExecutionContext context;
   int64_t context_ptr = reinterpret_cast<int64_t>(&context);