cmake: Document '--preset <preset>' form of the argument

This form already works.  Document it and add tests.

Issue: #21855

Help/manual/cmake.1.rst

@@ -377,7 +377,7 @@ Options
  about:tracing tab of Google Chrome or using a plugin for a tool like Trace
  Compass.
 
-``--preset=<preset>``
+``--preset <preset>``, ``--preset=<preset>``
  Reads a :manual:`preset <cmake-presets(7)>` from
  ``<path-to-source>/CMakePresets.json`` and
  ``<path-to-source>/CMakeUserPresets.json``. The preset specifies the

Source/cmakemain.cxx

@@ -64,7 +64,7 @@ const char* cmDocumentationUsageNote[][2] = {
 
 const char* cmDocumentationOptions[][2] = {
   CMAKE_STANDARD_OPTIONS_TABLE,
-  { "--preset=<preset>", "Specify a configure preset." },
+  { "--preset <preset>,--preset=<preset>", "Specify a configure preset." },
   { "--list-presets", "List available presets." },
   { "-E", "CMake command mode." },
   { "-L[A][H]", "List non-advanced cached variables." },

Tests/RunCMake/CMakePresets/CMakePresets.json.in

@@ -132,7 +132,13 @@
     {
       "name": "Good Spaces",
       "generator": "@RunCMake_GENERATOR@",
-      "binaryDir": "${sourceDir}/build"
+      "binaryDir": "${sourceDir}/build",
+      "cacheVariables": {
+        "GOOD_SPACES": {
+          "type": "STRING",
+          "value": "1"
+        }
+      }
     },
     {
       "name": "GoodWindowsBackslash",

Tests/RunCMake/CMakePresets/GoodSpaces-stdout.txt

+Preset CMake variables:
+
+  GOOD_SPACES:STRING="1"

Tests/RunCMake/CMakePresets/GoodSpacesEq-stdout.txt

+Preset CMake variables:
+
+  GOOD_SPACES:STRING="1"

Tests/RunCMake/CMakePresets/NoPresetArgumentEq-result.txt

+1

Tests/RunCMake/CMakePresets/NoPresetArgumentEq-stderr.txt

+^CMake Error: No preset specified for --preset
+CMake Error: Run 'cmake --help' for all supported options.$

Tests/RunCMake/CMakePresets/RunCMakeTest.cmake

@@ -143,7 +143,8 @@ run_cmake_presets(GoodBinaryUp)
 set(CMakePresets_SOURCE_ARG "../GoodBinaryRelative")
 run_cmake_presets(GoodBinaryRelative)
 unset(CMakePresets_SOURCE_ARG)
-run_cmake_presets(GoodSpaces "--preset=Good Spaces")
+run_cmake_presets(GoodSpaces "--preset" "Good Spaces")
+run_cmake_presets(GoodSpacesEq "--preset=Good Spaces")
 if(WIN32)
   run_cmake_presets(GoodWindowsBackslash)
 endif()
@@ -206,7 +207,8 @@ endif()
 
 # Test bad command line arguments
 run_cmake_presets(NoSuchPreset)
-run_cmake_presets(NoPresetArgument --preset=)
+run_cmake_presets(NoPresetArgument --preset)
+run_cmake_presets(NoPresetArgumentEq --preset= -DA=B)
 run_cmake_presets(UseHiddenPreset)
 
 # Test CMakeUserPresets.json