Merge topic 'cmake-presets-host-system-name'

0d497e159b CMakePresets.json: Add ${hostSystemName} macro
79d03ab505 Help: Fix version numbers in CMakePresets.json documentation
69527a1979 Refactor: Pass CMakePresets.json version to ExpandMacros() functions
ad19da011d Refactor: Add cmSystemTools::GetSystemName()

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !5902

15 files changed, 219 insertions, 110 deletions

diff --git a/Help/manual/cmake-presets.7.rst b/Help/manual/cmake-presets.7.rst
index 3d2ada8..5273236 100644
--- a/Help/manual/cmake-presets.7.rst
+++ b/Help/manual/cmake-presets.7.rst
@@ -39,7 +39,7 @@ The root object recognizes the following fields:
 ``version``
 
   A required integer representing the version of the JSON schema.
-  The supported versions are ``1`` and ``2``.
+  The supported versions are ``1``, ``2``, and ``3``.
 
 ``cmakeMinimumRequired``
 
@@ -70,17 +70,17 @@ The root object recognizes the following fields:
 ``configurePresets``
 
   An optional array of `Configure Preset`_ objects.
-  This is allowed in preset files specifying version 1 or above.
+  This is allowed in preset files specifying version ``1`` or above.
 
 ``buildPresets``
 
   An optional array of `Build Preset`_ objects.
-  This is allowed in preset files specifying version 2 or above.
+  This is allowed in preset files specifying version ``2`` or above.
 
 ``testPresets``
 
   An optional array of `Test Preset`_ objects.
-  This is allowed in preset files specifying version 2 or above.
+  This is allowed in preset files specifying version ``2`` or above.
 
 Configure Preset
 ^^^^^^^^^^^^^^^^
@@ -187,7 +187,8 @@ that may contain the following fields:
 
   An optional string representing the path to the installation directory.
   This field supports `macro expansion`_. If a relative path is specified,
-  it is calculated relative to the source directory.
+  it is calculated relative to the source directory. This is allowed in
+  preset files specifying version ``3`` or above.
 
 ``cmakeExecutable``
 
@@ -829,6 +830,12 @@ Recognized macros include:
   test presets, this will evaluate to the generator specified by
   ``configurePreset``.
 
+``${hostSystemName}``
+
+  The name of the host operating system. Contains the same value as
+  :variable:`CMAKE_HOST_SYSTEM_NAME`. This is allowed in preset files
+  specifying version ``3`` or above.
+
 ``${dollar}``
 
   A literal dollar sign (``$``).
diff --git a/Help/release/dev/cmake-presets-host-system-name.rst b/Help/release/dev/cmake-presets-host-system-name.rst
new file mode 100644
index 0000000..8036939
--- /dev/null
+++ b/Help/release/dev/cmake-presets-host-system-name.rst
@@ -0,0 +1,5 @@
+cmake-presets-host-system-name
+------------------------------
+
+* :manual:`cmake-presets(7)` gained support for a new ``${hostSystemName}``
+  macro.
diff --git a/Help/release/dev/cmake-system-name-version.rst b/Help/release/dev/cmake-system-name-version.rst
new file mode 100644
index 0000000..9cfe401
--- /dev/null
+++ b/Help/release/dev/cmake-system-name-version.rst
@@ -0,0 +1,10 @@
+cmake-system-name-version
+-------------------------
+
+* :variable:`CMAKE_HOST_SYSTEM_NAME`'s undocumented version-stripping behavior
+  has been moved earlier, before :command:`project` or
+  :command:`enable_language` is called.
+* :variable:`CMAKE_SYSTEM_NAME`'s undocumented version-stripping behavior has
+  been removed entirely. If it is set by a ``-D`` flag or by a
+  :manual:`toolchain file <cmake-toolchains(7)>`, it is left unaltered, even if
+  it still contains a version number.
diff --git a/Modules/CMakeDetermineSystem.cmake b/Modules/CMakeDetermineSystem.cmake
index bae270d..c3f2b74 100644
--- a/Modules/CMakeDetermineSystem.cmake
+++ b/Modules/CMakeDetermineSystem.cmake
@@ -158,37 +158,14 @@ endif()
 
 include(Platform/${CMAKE_SYSTEM_NAME}-Determine OPTIONAL)
 
-macro(ADJUST_CMAKE_SYSTEM_VARIABLES _PREFIX)
-  if(NOT ${_PREFIX}_NAME)
-    set(${_PREFIX}_NAME "UnknownOS")
-  endif()
-
-  # fix for BSD/OS , remove the /
-  if(${_PREFIX}_NAME MATCHES BSD.OS)
-    set(${_PREFIX}_NAME BSDOS)
-  endif()
-
-  # fix for GNU/kFreeBSD, remove the GNU/
-  if(${_PREFIX}_NAME MATCHES kFreeBSD)
-    set(${_PREFIX}_NAME kFreeBSD)
-  endif()
-
-  # fix for CYGWIN which has windows version in it
-  if(${_PREFIX}_NAME MATCHES CYGWIN)
-    set(${_PREFIX}_NAME CYGWIN)
-  endif()
-
-  # set CMAKE_SYSTEM to the CMAKE_SYSTEM_NAME
-  set(${_PREFIX}  ${${_PREFIX}_NAME})
-  # if there is a CMAKE_SYSTEM_VERSION then add a -${CMAKE_SYSTEM_VERSION}
-  if(${_PREFIX}_VERSION)
-    set(${_PREFIX} ${${_PREFIX}}-${${_PREFIX}_VERSION})
-  endif()
-
-endmacro()
-
-ADJUST_CMAKE_SYSTEM_VARIABLES(CMAKE_SYSTEM)
-ADJUST_CMAKE_SYSTEM_VARIABLES(CMAKE_HOST_SYSTEM)
+set(CMAKE_SYSTEM ${CMAKE_SYSTEM_NAME})
+if(CMAKE_SYSTEM_VERSION)
+  string(APPEND CMAKE_SYSTEM -${CMAKE_SYSTEM_VERSION})
+endif()
+set(CMAKE_HOST_SYSTEM ${CMAKE_HOST_SYSTEM_NAME})
+if(CMAKE_HOST_SYSTEM_VERSION)
+  string(APPEND CMAKE_HOST_SYSTEM -${CMAKE_HOST_SYSTEM_VERSION})
+endif()
 
 # this file is also executed from cpack, then we don't need to generate these files
 # in this case there is no CMAKE_BINARY_DIR
diff --git a/Source/cmCMakePresetsFile.cxx b/Source/cmCMakePresetsFile.cxx
index e9e8c4c..7726927 100644
--- a/Source/cmCMakePresetsFile.cxx
+++ b/Source/cmCMakePresetsFile.cxx
@@ -9,6 +9,7 @@
 #include <iterator>
 #include <utility>
 
+#include <cm/string_view>
 #include <cmext/string_view>
 
 #include <cm3p/json/reader.h>
@@ -28,9 +29,9 @@
       return _result;                                                         \
   }
 
-#define CHECK_EXPAND(out, field, expanders)                                   \
+#define CHECK_EXPAND(out, field, expanders, version)                          \
   {                                                                           \
-    switch (ExpandMacros(field, expanders)) {                                 \
+    switch (ExpandMacros(field, expanders, version)) {                        \
       case ExpandMacroResult::Error:                                          \
         return false;                                                         \
       case ExpandMacroResult::Ignore:                                         \
@@ -849,16 +850,19 @@ enum class ExpandMacroResult
 };
 
 using MacroExpander = std::function<ExpandMacroResult(
-  const std::string&, const std::string&, std::string&)>;
+  const std::string&, const std::string&, std::string&, int version)>;
 
 ExpandMacroResult VisitEnv(std::string& value, CycleStatus& status,
-                           const std::vector<MacroExpander>& macroExpanders);
+                           const std::vector<MacroExpander>& macroExpanders,
+                           int version);
 ExpandMacroResult ExpandMacros(
-  std::string& out, const std::vector<MacroExpander>& macroExpanders);
-ExpandMacroResult ExpandMacro(
-  std::string& out, const std::string& macroNamespace,
-  const std::string& macroName,
-  const std::vector<MacroExpander>& macroExpanders);
+  std::string& out, const std::vector<MacroExpander>& macroExpanders,
+  int version);
+ExpandMacroResult ExpandMacro(std::string& out,
+                              const std::string& macroNamespace,
+                              const std::string& macroName,
+                              const std::vector<MacroExpander>& macroExpanders,
+                              int version);
 
 bool ExpandMacros(const cmCMakePresetsFile& file,
                   const ConfigurePreset& preset,
@@ -866,7 +870,7 @@ bool ExpandMacros(const cmCMakePresetsFile& file,
                   const std::vector<MacroExpander>& macroExpanders)
 {
   std::string binaryDir = preset.BinaryDir;
-  CHECK_EXPAND(out, binaryDir, macroExpanders)
+  CHECK_EXPAND(out, binaryDir, macroExpanders, file.GetVersion(preset))
 
   if (!cmSystemTools::FileIsFullPath(binaryDir)) {
     binaryDir = cmStrCat(file.SourceDir, '/', binaryDir);
@@ -876,7 +880,7 @@ bool ExpandMacros(const cmCMakePresetsFile& file,
 
   if (!preset.InstallDir.empty()) {
     std::string installDir = preset.InstallDir;
-    CHECK_EXPAND(out, installDir, macroExpanders)
+    CHECK_EXPAND(out, installDir, macroExpanders, file.GetVersion(preset))
 
     if (!cmSystemTools::FileIsFullPath(installDir)) {
       installDir = cmStrCat(file.SourceDir, '/', installDir);
@@ -887,67 +891,76 @@ bool ExpandMacros(const cmCMakePresetsFile& file,
 
   for (auto& variable : out->CacheVariables) {
     if (variable.second) {
-      CHECK_EXPAND(out, variable.second->Value, macroExpanders)
+      CHECK_EXPAND(out, variable.second->Value, macroExpanders,
+                   file.GetVersion(preset))
     }
   }
 
   return true;
 }
 
-bool ExpandMacros(const cmCMakePresetsFile&, const BuildPreset&,
+bool ExpandMacros(const cmCMakePresetsFile& file, const BuildPreset& preset,
                   cm::optional<BuildPreset>& out,
                   const std::vector<MacroExpander>& macroExpanders)
 {
   for (auto& target : out->Targets) {
-    CHECK_EXPAND(out, target, macroExpanders)
+    CHECK_EXPAND(out, target, macroExpanders, file.GetVersion(preset))
   }
 
   for (auto& nativeToolOption : out->NativeToolOptions) {
-    CHECK_EXPAND(out, nativeToolOption, macroExpanders)
+    CHECK_EXPAND(out, nativeToolOption, macroExpanders,
+                 file.GetVersion(preset))
   }
 
   return true;
 }
 
-bool ExpandMacros(const cmCMakePresetsFile&, const TestPreset&,
+bool ExpandMacros(const cmCMakePresetsFile& file, const TestPreset& preset,
                   cm::optional<TestPreset>& out,
                   const std::vector<MacroExpander>& macroExpanders)
 {
   for (auto& overwrite : out->OverwriteConfigurationFile) {
-    CHECK_EXPAND(out, overwrite, macroExpanders);
+    CHECK_EXPAND(out, overwrite, macroExpanders, file.GetVersion(preset));
   }
 
   if (out->Output) {
-    CHECK_EXPAND(out, out->Output->OutputLogFile, macroExpanders)
+    CHECK_EXPAND(out, out->Output->OutputLogFile, macroExpanders,
+                 file.GetVersion(preset))
   }
 
   if (out->Filter) {
     if (out->Filter->Include) {
-      CHECK_EXPAND(out, out->Filter->Include->Name, macroExpanders)
-      CHECK_EXPAND(out, out->Filter->Include->Label, macroExpanders)
+      CHECK_EXPAND(out, out->Filter->Include->Name, macroExpanders,
+                   file.GetVersion(preset))
+      CHECK_EXPAND(out, out->Filter->Include->Label, macroExpanders,
+                   file.GetVersion(preset))
 
       if (out->Filter->Include->Index) {
         CHECK_EXPAND(out, out->Filter->Include->Index->IndexFile,
-                     macroExpanders);
+                     macroExpanders, file.GetVersion(preset));
       }
     }
 
     if (out->Filter->Exclude) {
-      CHECK_EXPAND(out, out->Filter->Exclude->Name, macroExpanders)
-      CHECK_EXPAND(out, out->Filter->Exclude->Label, macroExpanders)
+      CHECK_EXPAND(out, out->Filter->Exclude->Name, macroExpanders,
+                   file.GetVersion(preset))
+      CHECK_EXPAND(out, out->Filter->Exclude->Label, macroExpanders,
+                   file.GetVersion(preset))
 
       if (out->Filter->Exclude->Fixtures) {
-        CHECK_EXPAND(out, out->Filter->Exclude->Fixtures->Any, macroExpanders)
+        CHECK_EXPAND(out, out->Filter->Exclude->Fixtures->Any, macroExpanders,
+                     file.GetVersion(preset))
         CHECK_EXPAND(out, out->Filter->Exclude->Fixtures->Setup,
-                     macroExpanders)
+                     macroExpanders, file.GetVersion(preset))
         CHECK_EXPAND(out, out->Filter->Exclude->Fixtures->Cleanup,
-                     macroExpanders)
+                     macroExpanders, file.GetVersion(preset))
       }
     }
   }
 
   if (out->Execution) {
-    CHECK_EXPAND(out, out->Execution->ResourceSpecFile, macroExpanders)
+    CHECK_EXPAND(out, out->Execution->ResourceSpecFile, macroExpanders,
+                 file.GetVersion(preset))
   }
 
   return true;
@@ -968,8 +981,8 @@ bool ExpandMacros(const cmCMakePresetsFile& file, const T& preset,
 
   MacroExpander defaultMacroExpander =
     [&file, &preset](const std::string& macroNamespace,
-                     const std::string& macroName,
-                     std::string& macroOut) -> ExpandMacroResult {
+                     const std::string& macroName, std::string& macroOut,
+                     int version) -> ExpandMacroResult {
     if (macroNamespace.empty()) {
       if (macroName == "sourceDir") {
         macroOut += file.SourceDir;
@@ -998,6 +1011,13 @@ bool ExpandMacros(const cmCMakePresetsFile& file, const T& preset,
         macroOut += '$';
         return ExpandMacroResult::Ok;
       }
+      if (macroName == "hostSystemName") {
+        if (version < 3) {
+          return ExpandMacroResult::Error;
+        }
+        macroOut += cmSystemTools::GetSystemName();
+        return ExpandMacroResult::Ok;
+      }
     }
 
     return ExpandMacroResult::Ignore;
@@ -1006,11 +1026,12 @@ bool ExpandMacros(const cmCMakePresetsFile& file, const T& preset,
   MacroExpander environmentMacroExpander =
     [&macroExpanders, &out, &envCycles](
       const std::string& macroNamespace, const std::string& macroName,
-      std::string& result) -> ExpandMacroResult {
+      std::string& result, int version) -> ExpandMacroResult {
     if (macroNamespace == "env" && !macroName.empty() && out) {
       auto v = out->Environment.find(macroName);
       if (v != out->Environment.end() && v->second) {
-        auto e = VisitEnv(*v->second, envCycles[macroName], macroExpanders);
+        auto e =
+          VisitEnv(*v->second, envCycles[macroName], macroExpanders, version);
         if (e != ExpandMacroResult::Ok) {
           return e;
         }
@@ -1038,7 +1059,8 @@ bool ExpandMacros(const cmCMakePresetsFile& file, const T& preset,
 
   for (auto& v : out->Environment) {
     if (v.second) {
-      switch (VisitEnv(*v.second, envCycles[v.first], macroExpanders)) {
+      switch (VisitEnv(*v.second, envCycles[v.first], macroExpanders,
+                       file.GetVersion(preset))) {
         case ExpandMacroResult::Error:
           return false;
         case ExpandMacroResult::Ignore:
@@ -1054,7 +1076,8 @@ bool ExpandMacros(const cmCMakePresetsFile& file, const T& preset,
 }
 
 ExpandMacroResult VisitEnv(std::string& value, CycleStatus& status,
-                           const std::vector<MacroExpander>& macroExpanders)
+                           const std::vector<MacroExpander>& macroExpanders,
+                           int version)
 {
   if (status == CycleStatus::Verified) {
     return ExpandMacroResult::Ok;
@@ -1064,7 +1087,7 @@ ExpandMacroResult VisitEnv(std::string& value, CycleStatus& status,
   }
 
   status = CycleStatus::InProgress;
-  auto e = ExpandMacros(value, macroExpanders);
+  auto e = ExpandMacros(value, macroExpanders, version);
   if (e != ExpandMacroResult::Ok) {
     return e;
   }
@@ -1073,7 +1096,8 @@ ExpandMacroResult VisitEnv(std::string& value, CycleStatus& status,
 }
 
 ExpandMacroResult ExpandMacros(
-  std::string& out, const std::vector<MacroExpander>& macroExpanders)
+  std::string& out, const std::vector<MacroExpander>& macroExpanders,
+  int version)
 {
   std::string result;
   std::string macroNamespace;
@@ -1120,8 +1144,8 @@ ExpandMacroResult ExpandMacros(
 
       case State::MacroName:
         if (c == '}') {
-          auto e =
-            ExpandMacro(result, macroNamespace, macroName, macroExpanders);
+          auto e = ExpandMacro(result, macroNamespace, macroName,
+                               macroExpanders, version);
           if (e != ExpandMacroResult::Ok) {
             return e;
           }
@@ -1153,10 +1177,11 @@ ExpandMacroResult ExpandMacros(
 ExpandMacroResult ExpandMacro(std::string& out,
                               const std::string& macroNamespace,
                               const std::string& macroName,
-                              const std::vector<MacroExpander>& macroExpanders)
+                              const std::vector<MacroExpander>& macroExpanders,
+                              int version)
 {
   for (auto const& macroExpander : macroExpanders) {
-    auto result = macroExpander(macroNamespace, macroName, out);
+    auto result = macroExpander(macroNamespace, macroName, out, version);
     if (result != ExpandMacroResult::Ignore) {
       return result;
     }
@@ -1549,6 +1574,11 @@ cmCMakePresetsFile::ReadFileResult cmCMakePresetsFile::ReadJSONFile(
   if (v < MIN_VERSION || v > MAX_VERSION) {
     return ReadFileResult::UNRECOGNIZED_VERSION;
   }
+  if (user) {
+    this->UserVersion = v;
+  } else {
+    this->Version = v;
+  }
 
   // Support for build and test presets added in version 2.
   if (v < 2 &&
diff --git a/Source/cmCMakePresetsFile.h b/Source/cmCMakePresetsFile.h
index 517215d..eed0eab 100644
--- a/Source/cmCMakePresetsFile.h
+++ b/Source/cmCMakePresetsFile.h
@@ -294,6 +294,13 @@ public:
   std::vector<std::string> TestPresetOrder;
 
   std::string SourceDir;
+  int Version;
+  int UserVersion;
+
+  int GetVersion(const Preset& preset) const
+  {
+    return preset.User ? this->UserVersion : this->Version;
+  }
 
   static std::string GetFilename(const std::string& sourceDir);
   static std::string GetUserFilename(const std::string& sourceDir);
diff --git a/Source/cmStateSnapshot.cxx b/Source/cmStateSnapshot.cxx
index 1e20abb..fbf47ef 100644
--- a/Source/cmStateSnapshot.cxx
+++ b/Source/cmStateSnapshot.cxx
@@ -16,16 +16,9 @@
 #include "cmState.h"
 #include "cmStateDirectory.h"
 #include "cmStatePrivate.h"
+#include "cmSystemTools.h"
 #include "cmVersion.h"
 
-#if !defined(_WIN32)
-#  include <sys/utsname.h>
-#endif
-
-#if defined(__CYGWIN__)
-#  include "cmSystemTools.h"
-#endif
-
 cmStateSnapshot::cmStateSnapshot(cmState* state)
   : State(state)
 {
@@ -292,34 +285,26 @@ void InitializeContentFromParent(T& parentContent, T& thisContent,
 
 void cmStateSnapshot::SetDefaultDefinitions()
 {
-/* Up to CMake 2.4 here only WIN32, UNIX and APPLE were set.
-  With CMake must separate between target and host platform. In most cases
-  the tests for WIN32, UNIX and APPLE will be for the target system, so an
-  additional set of variables for the host system is required ->
-  CMAKE_HOST_WIN32, CMAKE_HOST_UNIX, CMAKE_HOST_APPLE.
-  WIN32, UNIX and APPLE are now set in the platform files in
-  Modules/Platforms/.
-  To keep cmake scripts (-P) and custom language and compiler modules
-  working, these variables are still also set here in this place, but they
-  will be reset in CMakeSystemSpecificInformation.cmake before the platform
-  files are executed. */
-#if defined(_WIN32)
-  this->SetDefinition("WIN32", "1");
-  this->SetDefinition("CMAKE_HOST_WIN32", "1");
-  this->SetDefinition("CMAKE_HOST_SYSTEM_NAME", "Windows");
-#else
-  this->SetDefinition("UNIX", "1");
-  this->SetDefinition("CMAKE_HOST_UNIX", "1");
-
-#  if defined(__ANDROID__)
-  this->SetDefinition("CMAKE_HOST_SYSTEM_NAME", "Android");
-#  else
-  struct utsname uts_name;
-  if (uname(&uts_name) >= 0) {
-    this->SetDefinition("CMAKE_HOST_SYSTEM_NAME", uts_name.sysname);
+  /* Up to CMake 2.4 here only WIN32, UNIX and APPLE were set.
+    With CMake must separate between target and host platform. In most cases
+    the tests for WIN32, UNIX and APPLE will be for the target system, so an
+    additional set of variables for the host system is required ->
+    CMAKE_HOST_WIN32, CMAKE_HOST_UNIX, CMAKE_HOST_APPLE.
+    WIN32, UNIX and APPLE are now set in the platform files in
+    Modules/Platforms/.
+    To keep cmake scripts (-P) and custom language and compiler modules
+    working, these variables are still also set here in this place, but they
+    will be reset in CMakeSystemSpecificInformation.cmake before the platform
+    files are executed. */
+  cm::string_view hostSystemName = cmSystemTools::GetSystemName();
+  this->SetDefinition("CMAKE_HOST_SYSTEM_NAME", hostSystemName);
+  if (hostSystemName == "Windows") {
+    this->SetDefinition("WIN32", "1");
+    this->SetDefinition("CMAKE_HOST_WIN32", "1");
+  } else {
+    this->SetDefinition("UNIX", "1");
+    this->SetDefinition("CMAKE_HOST_UNIX", "1");
   }
-#  endif
-#endif
 #if defined(__CYGWIN__)
   std::string legacy;
   if (cmSystemTools::GetEnv("CMAKE_LEGACY_CYGWIN_WIN32", legacy) &&
diff --git a/Source/cmSystemTools.cxx b/Source/cmSystemTools.cxx
index 87ba152..e8e1018 100644
--- a/Source/cmSystemTools.cxx
+++ b/Source/cmSystemTools.cxx
@@ -103,6 +103,10 @@
 #  include <malloc.h> /* for malloc/free on QNX */
 #endif
 
+#if !defined(_WIN32) && !defined(__ANDROID__)
+#  include <sys/utsname.h>
+#endif
+
 namespace {
 
 cmSystemTools::InterruptCallback s_InterruptCallback;
@@ -3207,3 +3211,46 @@ bool cmSystemTools::CreateLink(const std::string& origName,
 
   return true;
 }
+
+cm::string_view cmSystemTools::GetSystemName()
+{
+#if defined(_WIN32)
+  return "Windows";
+#elif defined(__ANDROID__)
+  return "Android";
+#else
+  static struct utsname uts_name;
+  static bool initialized = false;
+  static cm::string_view systemName;
+  if (initialized) {
+    return systemName;
+  }
+  if (uname(&uts_name) >= 0) {
+    initialized = true;
+    systemName = uts_name.sysname;
+
+    if (cmIsOff(systemName)) {
+      systemName = "UnknownOS";
+    }
+
+    // fix for BSD/OS, remove the /
+    static const cmsys::RegularExpression bsdOsRegex("BSD.OS");
+    cmsys::RegularExpressionMatch match;
+    if (bsdOsRegex.find(uts_name.sysname, match)) {
+      systemName = "BSDOS";
+    }
+
+    // fix for GNU/kFreeBSD, remove the GNU/
+    if (systemName.find("kFreeBSD") != cm::string_view::npos) {
+      systemName = "kFreeBSD";
+    }
+
+    // fix for CYGWIN which has windows version in it
+    if (systemName.find("CYGWIN") != cm::string_view::npos) {
+      systemName = "CYGWIN";
+    }
+    return systemName;
+  }
+  return "";
+#endif
+}
diff --git a/Source/cmSystemTools.h b/Source/cmSystemTools.h
index 2ff4c5d..5620899 100644
--- a/Source/cmSystemTools.h
+++ b/Source/cmSystemTools.h
@@ -498,6 +498,9 @@ public:
                          const std::string& newName,
                          std::string* errorMessage = nullptr);
 
+  /** Get the system name. */
+  static cm::string_view GetSystemName();
+
 private:
   static bool s_ForceUnixPaths;
   static bool s_RunCommandHideConsole;
diff --git a/Tests/RunCMake/CMakePresets/HostSystemName.cmake b/Tests/RunCMake/CMakePresets/HostSystemName.cmake
new file mode 100644
index 0000000..dc0998a
--- /dev/null
+++ b/Tests/RunCMake/CMakePresets/HostSystemName.cmake
@@ -0,0 +1,3 @@
+include(${CMAKE_CURRENT_LIST_DIR}/TestVariable.cmake)
+
+test_variable(TEST_HOST_SYSTEM_NAME "" "${CMAKE_HOST_SYSTEM_NAME}")
diff --git a/Tests/RunCMake/CMakePresets/HostSystemName.json.in b/Tests/RunCMake/CMakePresets/HostSystemName.json.in
new file mode 100644
index 0000000..7fcd8c8
--- /dev/null
+++ b/Tests/RunCMake/CMakePresets/HostSystemName.json.in
@@ -0,0 +1,13 @@
+{
+  "version": 3,
+  "configurePresets": [
+    {
+      "name": "HostSystemName",
+      "generator": "@RunCMake_GENERATOR@",
+      "binaryDir": "${sourceDir}/build",
+      "cacheVariables": {
+        "TEST_HOST_SYSTEM_NAME": "${hostSystemName}"
+      }
+    }
+  ]
+}
diff --git a/Tests/RunCMake/CMakePresets/HostSystemNameFuture-result.txt b/Tests/RunCMake/CMakePresets/HostSystemNameFuture-result.txt
new file mode 100644
index 0000000..d00491f
--- /dev/null
+++ b/Tests/RunCMake/CMakePresets/HostSystemNameFuture-result.txt
@@ -0,0 +1 @@
+1
diff --git a/Tests/RunCMake/CMakePresets/HostSystemNameFuture-stderr.txt b/Tests/RunCMake/CMakePresets/HostSystemNameFuture-stderr.txt
new file mode 100644
index 0000000..7f4bb9a
--- /dev/null
+++ b/Tests/RunCMake/CMakePresets/HostSystemNameFuture-stderr.txt
@@ -0,0 +1,2 @@
+^CMake Error: Could not read presets from [^
+]*/Tests/RunCMake/CMakePresets/HostSystemNameFuture: Invalid macro expansion$
diff --git a/Tests/RunCMake/CMakePresets/HostSystemNameFuture.json.in b/Tests/RunCMake/CMakePresets/HostSystemNameFuture.json.in
new file mode 100644
index 0000000..7a2f0aa
--- /dev/null
+++ b/Tests/RunCMake/CMakePresets/HostSystemNameFuture.json.in
@@ -0,0 +1,13 @@
+{
+  "version": 2,
+  "configurePresets": [
+    {
+      "name": "HostSystemNameFuture",
+      "generator": "@RunCMake_GENERATOR@",
+      "binaryDir": "${sourceDir}/build",
+      "cacheVariables": {
+        "TEST_HOST_SYSTEM_NAME": "${hostSystemName}"
+      }
+    }
+  ]
+}
diff --git a/Tests/RunCMake/CMakePresets/RunCMakeTest.cmake b/Tests/RunCMake/CMakePresets/RunCMakeTest.cmake
index ee21130..24ac0e9 100644
--- a/Tests/RunCMake/CMakePresets/RunCMakeTest.cmake
+++ b/Tests/RunCMake/CMakePresets/RunCMakeTest.cmake
@@ -261,6 +261,12 @@ set(CMakePresets_FILE "${RunCMake_SOURCE_DIR}/Debug.json.in")
 run_cmake_presets(NoDebug)
 run_cmake_presets(Debug)
 
+# Test ${hostSystemName} macro
+set(CMakePresets_FILE "${RunCMake_SOURCE_DIR}/HostSystemName.json.in")
+run_cmake_presets(HostSystemName)
+set(CMakePresets_FILE "${RunCMake_SOURCE_DIR}/HostSystemNameFuture.json.in")
+run_cmake_presets(HostSystemNameFuture)
+
 # Test the example from the documentation
 file(READ "${RunCMake_SOURCE_DIR}/../../../Help/manual/presets/example.json" _example)
 string(REPLACE "\"generator\": \"Ninja\"" "\"generator\": \"@RunCMake_GENERATOR@\"" _example "${_example}")