SERVER-40160 Remove `if_constexpr.h` header.

This header circumvented bad formatting which `clang-format-3.8`
imparted to `if constexpr`.  Now `clang-format-7.0.1` imparts
a reasonable format to `if constexpr` so this header is not
needed anymore.

1 files changed, 3 insertions, 6 deletions

diff --git a/src/mongo/bson/bsonobjbuilder.h b/src/mongo/bson/bsonobjbuilder.h
index 1eb052a7c21..de68ff65353 100644
--- a/src/mongo/bson/bsonobjbuilder.h
+++ b/src/mongo/bson/bsonobjbuilder.h
@@ -50,7 +50,6 @@
 #include "mongo/bson/util/builder.h"
 #include "mongo/platform/decimal128.h"
 #include "mongo/util/decimal_counter.h"
-#include "mongo/util/if_constexpr.h"
 #include "mongo/util/scopeguard.h"
 
 namespace mongo {
@@ -262,13 +261,11 @@ public:
         constexpr BSONType type = BSONObjAppendFormat<T>::value;
         _b.appendNum(static_cast<char>(type));
         _b.appendStr(fieldName);
-        IF_CONSTEXPR(type == Bool) {
+        if constexpr (type == Bool) {
             _b.appendNum(static_cast<char>(n));
-        }
-        else IF_CONSTEXPR(type == NumberInt) {
+        } else if constexpr (type == NumberInt) {
             _b.appendNum(static_cast<int>(n));
-        }
-        else {
+        } else {
             _b.appendNum(n);
         }
         return *this;