Intel: Update Classic compiler version detection for 2021

The value of the `__INTEL_COMPILER` macro changed convention starting
in version 2021.

Fixes: #22120

Help/release/3.20.rst

@@ -351,3 +351,11 @@ Changes made since CMake 3.20.0 include the following.
   iOS, tvOS and watchOS should now default to ``@rpath`` instead of using
   a full absolute path and failing at runtime when the library or framework
   is embedded in an application bundle (see :prop_tgt:`XCODE_EMBED_<type>`).
+
+3.20.2
+------
+
+* The Intel Classic 2021 compiler version numbers are now detected correctly
+  as having major version 2021.  CMake 3.20.1 and below were not aware of a
+  change to the identification macro version scheme made by Intel starting
+  in version 2021, and detected the version as 20.2.

Modules/CMakeFortranCompilerId.F.in

@@ -38,12 +38,21 @@
 # endif
 #elif defined(__INTEL_COMPILER) || defined(__ICC)
         PRINT *, 'INFO:compiler[Intel]'
-# define COMPILER_VERSION_MAJOR DEC(__INTEL_COMPILER/100)
-# define COMPILER_VERSION_MINOR DEC(__INTEL_COMPILER/10 % 10)
-# if defined(__INTEL_COMPILER_UPDATE)
-#  define COMPILER_VERSION_PATCH DEC(__INTEL_COMPILER_UPDATE)
+! __INTEL_COMPILER = VRP prior to 2021, and then VVVV for 2021 and later.
+# if __INTEL_COMPILER < 2021
+#  define COMPILER_VERSION_MAJOR DEC(__INTEL_COMPILER/100)
+#  define COMPILER_VERSION_MINOR DEC(__INTEL_COMPILER/10 % 10)
+#  if defined(__INTEL_COMPILER_UPDATE)
+#   define COMPILER_VERSION_PATCH DEC(__INTEL_COMPILER_UPDATE)
+#  else
+#   define COMPILER_VERSION_PATCH DEC(__INTEL_COMPILER   % 10)
+#  endif
 # else
-#  define COMPILER_VERSION_PATCH DEC(__INTEL_COMPILER   % 10)
+#  define COMPILER_VERSION_MAJOR DEC(__INTEL_COMPILER)
+#  define COMPILER_VERSION_MINOR DEC(__INTEL_COMPILER_UPDATE)
+!  The third version component from --version is an update index,
+!  but no macro is provided for it.
+#  define COMPILER_VERSION_PATCH DEC(0)
 # endif
 # if defined(__INTEL_COMPILER_BUILD_DATE)
 #  define COMPILER_VERSION_TWEAK DEC(__INTEL_COMPILER_BUILD_DATE)

Modules/Compiler/Intel-DetermineCompiler.cmake

@@ -2,16 +2,25 @@
 set(_compiler_id_pp_test "defined(__INTEL_COMPILER) || defined(__ICC)")
 
 set(_compiler_id_version_compute "
-  /* __INTEL_COMPILER = VRP */
-# define @PREFIX@COMPILER_VERSION_MAJOR @MACRO_DEC@(__INTEL_COMPILER/100)
-# define @PREFIX@COMPILER_VERSION_MINOR @MACRO_DEC@(__INTEL_COMPILER/10 % 10)
-# if defined(__INTEL_COMPILER_UPDATE)
-#  define @PREFIX@COMPILER_VERSION_PATCH @MACRO_DEC@(__INTEL_COMPILER_UPDATE)
+  /* __INTEL_COMPILER = VRP prior to 2021, and then VVVV for 2021 and later,
+     except that a few beta releases use the old format with V=2021.  */
+# if __INTEL_COMPILER < 2021 || __INTEL_COMPILER == 202110 || __INTEL_COMPILER == 202111
+#  define @PREFIX@COMPILER_VERSION_MAJOR @MACRO_DEC@(__INTEL_COMPILER/100)
+#  define @PREFIX@COMPILER_VERSION_MINOR @MACRO_DEC@(__INTEL_COMPILER/10 % 10)
+#  if defined(__INTEL_COMPILER_UPDATE)
+#   define @PREFIX@COMPILER_VERSION_PATCH @MACRO_DEC@(__INTEL_COMPILER_UPDATE)
+#  else
+#   define @PREFIX@COMPILER_VERSION_PATCH @MACRO_DEC@(__INTEL_COMPILER   % 10)
+#  endif
 # else
-#  define @PREFIX@COMPILER_VERSION_PATCH @MACRO_DEC@(__INTEL_COMPILER   % 10)
+#  define @PREFIX@COMPILER_VERSION_MAJOR @MACRO_DEC@(__INTEL_COMPILER)
+#  define @PREFIX@COMPILER_VERSION_MINOR @MACRO_DEC@(__INTEL_COMPILER_UPDATE)
+   /* The third version component from --version is an update index,
+      but no macro is provided for it.  */
+#  define @PREFIX@COMPILER_VERSION_PATCH @MACRO_DEC@(0)
 # endif
 # if defined(__INTEL_COMPILER_BUILD_DATE)
-  /* __INTEL_COMPILER_BUILD_DATE = YYYYMMDD */
+   /* __INTEL_COMPILER_BUILD_DATE = YYYYMMDD */
 #  define @PREFIX@COMPILER_VERSION_TWEAK @MACRO_DEC@(__INTEL_COMPILER_BUILD_DATE)
 # endif
 # if defined(_MSC_VER)