From 7f401ae43fafed8258659f2da204bc818fd693d3 Mon Sep 17 00:00:00 2001
From: Brad King <brad.king@kitware.com>
Date: Fri, 15 Apr 2016 16:06:41 -0400
Subject: [PATCH] Features: Detect C default dialect on MSVC-like compilers

These compilers default to C 90 but do not define __STDC__.  While MSVC
itself has no option to change the dialect, compilers that document
compatibility with MSVC and define _MSC_VER may (e.g. Intel).
---
 Modules/CMakeCCompilerId.c.in | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/Modules/CMakeCCompilerId.c.in b/Modules/CMakeCCompilerId.c.in
index c107dfdf5..95184c982 100644
--- a/Modules/CMakeCCompilerId.c.in
+++ b/Modules/CMakeCCompilerId.c.in
@@ -34,7 +34,11 @@ char const *info_cray = "INFO" ":" "compiler_wrapper[CrayPrgEnv]";
 @CMAKE_C_COMPILER_ID_ERROR_FOR_TEST@
 
 #if !defined(__STDC__)
-# define C_DIALECT
+# if defined(_MSC_VER) && !defined(__clang__)
+#  define C_DIALECT "90"
+# else
+#  define C_DIALECT
+# endif
 #elif __STDC_VERSION__ >= 201000L
 # define C_DIALECT "11"
 #elif __STDC_VERSION__ >= 199901L