7 files changed, 29 insertions, 0 deletions
diff --git a/Modules/Compiler/AppleClang-C.cmake b/Modules/Compiler/AppleClang-C.cmake
index 5908c26..1cc72c0 100644
--- a/Modules/Compiler/AppleClang-C.cmake
+++ b/Modules/Compiler/AppleClang-C.cmake
@@ -18,6 +18,9 @@ if(NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 4.0)
       message(FATAL_ERROR "CMAKE_C_STANDARD_COMPUTED_DEFAULT should be set for ${CMAKE_C_COMPILER_ID} (${CMAKE_C_COMPILER}) version ${CMAKE_C_COMPILER_VERSION}")
     endif()
     set(CMAKE_C_STANDARD_DEFAULT ${CMAKE_C_STANDARD_COMPUTED_DEFAULT})
+  elseif(NOT DEFINED CMAKE_C_STANDARD_DEFAULT)
+    # Compiler id was forced so just guess the default standard level.
+    set(CMAKE_C_STANDARD_DEFAULT 99)
   endif()
 endif()
 
diff --git a/Modules/Compiler/AppleClang-CXX.cmake b/Modules/Compiler/AppleClang-CXX.cmake
index c4e342b..95bc79a 100644
--- a/Modules/Compiler/AppleClang-CXX.cmake
+++ b/Modules/Compiler/AppleClang-CXX.cmake
@@ -28,6 +28,9 @@ if(NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.0)
       message(FATAL_ERROR "CMAKE_CXX_STANDARD_COMPUTED_DEFAULT should be set for ${CMAKE_CXX_COMPILER_ID} (${CMAKE_CXX_COMPILER}) version ${CMAKE_CXX_COMPILER_VERSION}")
     endif()
     set(CMAKE_CXX_STANDARD_DEFAULT ${CMAKE_CXX_STANDARD_COMPUTED_DEFAULT})
+  elseif(NOT DEFINED CMAKE_CXX_STANDARD_DEFAULT)
+    # Compiler id was forced so just guess the default standard level.
+    set(CMAKE_CXX_STANDARD_DEFAULT 98)
   endif()
 endif()
 
diff --git a/Modules/Compiler/Clang-C.cmake b/Modules/Compiler/Clang-C.cmake
index a2e81c1..d8b7743 100644
--- a/Modules/Compiler/Clang-C.cmake
+++ b/Modules/Compiler/Clang-C.cmake
@@ -23,6 +23,13 @@ if(NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 3.4)
       message(FATAL_ERROR "CMAKE_C_STANDARD_COMPUTED_DEFAULT should be set for ${CMAKE_C_COMPILER_ID} (${CMAKE_C_COMPILER}) version ${CMAKE_C_COMPILER_VERSION}")
     endif()
     set(CMAKE_C_STANDARD_DEFAULT ${CMAKE_C_STANDARD_COMPUTED_DEFAULT})
+  elseif(NOT DEFINED CMAKE_C_STANDARD_DEFAULT)
+    # Compiler id was forced so just guess the default standard level.
+    if (NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 3.6)
+      set(CMAKE_C_STANDARD_DEFAULT 11)
+    else()
+      set(CMAKE_C_STANDARD_DEFAULT 99)
+    endif()
   endif()
 endif()
 
diff --git a/Modules/Compiler/Clang-CXX.cmake b/Modules/Compiler/Clang-CXX.cmake
index 055a8ee..6a0a5e2 100644
--- a/Modules/Compiler/Clang-CXX.cmake
+++ b/Modules/Compiler/Clang-CXX.cmake
@@ -37,6 +37,9 @@ if(NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 3.4)
       message(FATAL_ERROR "CMAKE_CXX_STANDARD_COMPUTED_DEFAULT should be set for ${CMAKE_CXX_COMPILER_ID} (${CMAKE_CXX_COMPILER}) version ${CMAKE_CXX_COMPILER_VERSION}")
     endif()
     set(CMAKE_CXX_STANDARD_DEFAULT ${CMAKE_CXX_STANDARD_COMPUTED_DEFAULT})
+  elseif(NOT DEFINED CMAKE_CXX_STANDARD_DEFAULT)
+    # Compiler id was forced so just guess the default standard level.
+    set(CMAKE_CXX_STANDARD_DEFAULT 98)
   endif()
 endif()
 
diff --git a/Modules/Compiler/GNU-C.cmake b/Modules/Compiler/GNU-C.cmake
index d979fb7..2c478da 100644
--- a/Modules/Compiler/GNU-C.cmake
+++ b/Modules/Compiler/GNU-C.cmake
@@ -28,6 +28,13 @@ if(NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 4.4)
       message(FATAL_ERROR "CMAKE_C_STANDARD_COMPUTED_DEFAULT should be set for ${CMAKE_C_COMPILER_ID} (${CMAKE_C_COMPILER}) version ${CMAKE_C_COMPILER_VERSION}")
     endif()
     set(CMAKE_C_STANDARD_DEFAULT ${CMAKE_C_STANDARD_COMPUTED_DEFAULT})
+  elseif(NOT DEFINED CMAKE_C_STANDARD_DEFAULT)
+    # Compiler id was forced so just guess the default standard level.
+    if (NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 5.0)
+      set(CMAKE_C_STANDARD_DEFAULT 11)
+    else()
+      set(CMAKE_C_STANDARD_DEFAULT 90)
+    endif()
   endif()
 endif()
 
diff --git a/Modules/Compiler/GNU-CXX.cmake b/Modules/Compiler/GNU-CXX.cmake
index a7e71c3..e1c555b 100644
--- a/Modules/Compiler/GNU-CXX.cmake
+++ b/Modules/Compiler/GNU-CXX.cmake
@@ -40,6 +40,9 @@ if(NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.4)
       message(FATAL_ERROR "CMAKE_CXX_STANDARD_COMPUTED_DEFAULT should be set for ${CMAKE_CXX_COMPILER_ID} (${CMAKE_CXX_COMPILER}) version ${CMAKE_CXX_COMPILER_VERSION}")
     endif()
     set(CMAKE_CXX_STANDARD_DEFAULT ${CMAKE_CXX_STANDARD_COMPUTED_DEFAULT})
+  elseif(NOT DEFINED CMAKE_CXX_STANDARD_DEFAULT)
+    # Compiler id was forced so just guess the default standard level.
+    set(CMAKE_CXX_STANDARD_DEFAULT 98)
   endif()
 endif()
 
diff --git a/Modules/Compiler/SunPro-CXX.cmake b/Modules/Compiler/SunPro-CXX.cmake
index 50d68ee..b4a5591 100644
--- a/Modules/Compiler/SunPro-CXX.cmake
+++ b/Modules/Compiler/SunPro-CXX.cmake
@@ -42,6 +42,9 @@ if(NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 5.13)
       message(FATAL_ERROR "CMAKE_CXX_STANDARD_COMPUTED_DEFAULT should be set for ${CMAKE_CXX_COMPILER_ID} (${CMAKE_CXX_COMPILER}) version ${CMAKE_CXX_COMPILER_VERSION}")
     endif()
     set(CMAKE_CXX_STANDARD_DEFAULT ${CMAKE_CXX_STANDARD_COMPUTED_DEFAULT})
+  elseif(NOT DEFINED CMAKE_CXX_STANDARD_DEFAULT)
+    # Compiler id was forced so just guess the default standard level.
+    set(CMAKE_CXX_STANDARD_DEFAULT 98)
   endif()
 endif()