Merge topic 'find_package-PACKAGENAME_ROOT'

df9c4b1872 find_package: Use <PACKAGENAME>_ROOT variables as search prefixes
4da27a73bd Help: Document <PackageName>_ROOT variable ordering using an ordered list
bfeb16bd5b cmFindPackageCommand: Refactor CMP0074 logic to de-duplicate lookups
c0fcd07e6f cmFindPackageCommand: Factor out methods for package root stack management
acd9636d9d cmSystemTools: Add helpers for reading and parsing PATH env vars

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !8240

30 files changed, 761 insertions, 75 deletions

diff --git a/Help/command/FIND_XXX.txt b/Help/command/FIND_XXX.txt
index bd55e24..21236fa 100644
--- a/Help/command/FIND_XXX.txt
+++ b/Help/command/FIND_XXX.txt
@@ -140,21 +140,40 @@ If ``NO_DEFAULT_PATH`` is not specified, the search process is as follows:
    |prefix_XXX_SUBDIR| for each ``<prefix>`` in
    :variable:`CMAKE_SYSTEM_PREFIX_PATH`
 
-1. .. versionadded:: 3.12
-    If called from within a find module or any other script loaded by a call to
-    :command:`find_package(<PackageName>)`, search prefixes unique to the
-    current package being found.  Specifically, look in the
-    :variable:`<PackageName>_ROOT` CMake variable and the
-    :envvar:`<PackageName>_ROOT` environment variable.
-    The package root variables are maintained as a stack, so if called from
-    nested find modules or config packages, root paths from the parent's find
-    module or config package will be searched after paths from the current
-    module or package.  In other words, the search order would be
-    ``<CurrentPackage>_ROOT``, ``ENV{<CurrentPackage>_ROOT}``,
-    ``<ParentPackage>_ROOT``, ``ENV{<ParentPackage>_ROOT}``, etc.
-    This can be skipped if ``NO_PACKAGE_ROOT_PATH`` is passed or by setting
-    the :variable:`CMAKE_FIND_USE_PACKAGE_ROOT_PATH` to ``FALSE``.
-    See policy :policy:`CMP0074`.
+1. If called from within a find module or any other script loaded by a call to
+   :command:`find_package(<PackageName>)`, search prefixes unique to the
+   current package being found.  See policy :policy:`CMP0074`.
+
+   .. versionadded:: 3.12
+
+   Specifically, search paths specified by the following variables, in order:
+
+   a. :variable:`<PackageName>_ROOT` CMake variable,
+      where ``<PackageName>`` is the case-preserved package name.
+
+   b. :variable:`<PACKAGENAME>_ROOT` CMake variable,
+      where ``<PACKAGENAME>`` is the upper-cased package name.
+      See policy :policy:`CMP0144`.
+
+      .. versionadded:: 3.27
+
+   c. :envvar:`<PackageName>_ROOT` environment variable,
+      where ``<PackageName>`` is the case-preserved package name.
+
+   d. :envvar:`<PACKAGENAME>_ROOT` environment variable,
+      where ``<PACKAGENAME>`` is the upper-cased package name.
+      See policy :policy:`CMP0144`.
+
+      .. versionadded:: 3.27
+
+   The package root variables are maintained as a stack, so if called from
+   nested find modules or config packages, root paths from the parent's find
+   module or config package will be searched after paths from the current
+   module or package.  In other words, the search order would be
+   ``<CurrentPackage>_ROOT``, ``ENV{<CurrentPackage>_ROOT}``,
+   ``<ParentPackage>_ROOT``, ``ENV{<ParentPackage>_ROOT}``, etc.
+   This can be skipped if ``NO_PACKAGE_ROOT_PATH`` is passed or by setting
+   the :variable:`CMAKE_FIND_USE_PACKAGE_ROOT_PATH` to ``FALSE``.
 
    * |FIND_PACKAGE_ROOT_PREFIX_PATH_XXX|
 
diff --git a/Help/command/find_package.rst b/Help/command/find_package.rst
index de4cb88..b82088e 100644
--- a/Help/command/find_package.rst
+++ b/Help/command/find_package.rst
@@ -367,17 +367,37 @@ The set of installation prefixes is constructed using the following
 steps.  If ``NO_DEFAULT_PATH`` is specified all ``NO_*`` options are
 enabled.
 
-1. .. versionadded:: 3.12
-    Search paths specified in the :variable:`<PackageName>_ROOT` CMake
-    variable and the :envvar:`<PackageName>_ROOT` environment variable,
-    where ``<PackageName>`` is the package to be found
-    (the case-preserved first argument to ``find_package``).
-    The package root variables are maintained as a stack so if
-    called from within a find module, root paths from the parent's find
-    module will also be searched after paths for the current package.
-    This can be skipped if ``NO_PACKAGE_ROOT_PATH`` is passed or by setting
-    the :variable:`CMAKE_FIND_USE_PACKAGE_ROOT_PATH` to ``FALSE``.
-    See policy :policy:`CMP0074`.
+1. Search prefixes unique to the current ``<PackageName>`` being found.
+   See policy :policy:`CMP0074`.
+
+   .. versionadded:: 3.12
+
+   Specifically, search prefixes specified by the following variables,
+   in order:
+
+   a. :variable:`<PackageName>_ROOT` CMake variable,
+      where ``<PackageName>`` is the case-preserved package name.
+
+   b. :variable:`<PACKAGENAME>_ROOT` CMake variable,
+      where ``<PACKAGENAME>`` is the upper-cased package name.
+      See policy :policy:`CMP0144`.
+
+      .. versionadded:: 3.27
+
+   c. :envvar:`<PackageName>_ROOT` environment variable,
+      where ``<PackageName>`` is the case-preserved package name.
+
+   d. :envvar:`<PACKAGENAME>_ROOT` environment variable,
+      where ``<PACKAGENAME>`` is the upper-cased package name.
+      See policy :policy:`CMP0144`.
+
+      .. versionadded:: 3.27
+
+   The package root variables are maintained as a stack so if
+   called from within a find module, root paths from the parent's find
+   module will also be searched after paths for the current package.
+   This can be skipped if ``NO_PACKAGE_ROOT_PATH`` is passed or by setting
+   the :variable:`CMAKE_FIND_USE_PACKAGE_ROOT_PATH` to ``FALSE``.
 
 2. Search paths specified in cmake-specific cache variables.  These
    are intended to be used on the command line with a :option:`-DVAR=VALUE <cmake -D>`.
diff --git a/Help/envvar/PackageName_ROOT.rst b/Help/envvar/PackageName_ROOT.rst
index fa8c385..6e9c744 100644
--- a/Help/envvar/PackageName_ROOT.rst
+++ b/Help/envvar/PackageName_ROOT.rst
@@ -17,3 +17,17 @@ by ``:`` on UNIX or ``;`` on Windows (the same as the ``PATH`` environment
 variable convention on those platforms).
 
 See also the :variable:`<PackageName>_ROOT` CMake variable.
+
+.. envvar:: <PACKAGENAME>_ROOT
+
+  .. versionadded:: 3.27
+
+  Calls to :command:`find_package(<PackageName>)` will also search in
+  prefixes specified by the upper-case ``<PACKAGENAME>_ROOT`` environment
+  variable.  See policy :policy:`CMP0144`.
+
+.. note::
+
+  Note that the ``<PackageName>_ROOT`` and ``<PACKAGENAME>_ROOT``
+  environment variables are distinct only on platforms that have
+  case-sensitive environments.
diff --git a/Help/manual/cmake-policies.7.rst b/Help/manual/cmake-policies.7.rst
index 22e9eb2..e4c286d 100644
--- a/Help/manual/cmake-policies.7.rst
+++ b/Help/manual/cmake-policies.7.rst
@@ -51,6 +51,14 @@ The :variable:`CMAKE_MINIMUM_REQUIRED_VERSION` variable may also be used
 to determine whether to report an error on use of deprecated macros or
 functions.
 
+Policies Introduced by CMake 3.27
+=================================
+
+.. toctree::
+   :maxdepth: 1
+
+   CMP0144: find_package uses upper-case PACKAGENAME_ROOT variables. </policy/CMP0144>
+
 Policies Introduced by CMake 3.26
 =================================
 
diff --git a/Help/policy/CMP0144.rst b/Help/policy/CMP0144.rst
new file mode 100644
index 0000000..3959d96
--- /dev/null
+++ b/Help/policy/CMP0144.rst
@@ -0,0 +1,26 @@
+CMP0144
+-------
+
+.. versionadded:: 3.27
+
+:command:`find_package` uses upper-case ``<PACKAGENAME>_ROOT`` variables.
+
+In CMake 3.27 and above the :command:`find_package(<PackageName>)` command now
+searches prefixes specified by the upper-case :variable:`<PACKAGENAME>_ROOT`
+CMake variable and the :envvar:`<PACKAGENAME>_ROOT` environment variable
+in addition to the case-preserved :variable:`<PackageName>_ROOT` and
+:envvar:`<PackageName>_ROOT` variables used since policy :policy:`CMP0074`.
+This policy provides compatibility with projects that have not been
+updated to avoid using ``<PACKAGENAME>_ROOT`` variables for other purposes.
+
+The ``OLD`` behavior for this policy is to ignore ``<PACKAGENAME>_ROOT``
+variables if the original ``<PackageName>`` has lower-case characters.
+The ``NEW`` behavior for this policy is to use ``<PACKAGENAME>_ROOT``
+variables.
+
+This policy was introduced in CMake version 3.27.  CMake version
+|release| warns when the policy is not set and uses ``OLD`` behavior.
+Use the :command:`cmake_policy` command to set it to ``OLD`` or ``NEW``
+explicitly.
+
+.. include:: DEPRECATED.txt
diff --git a/Help/release/dev/find_package-PACKAGENAME_ROOT.rst b/Help/release/dev/find_package-PACKAGENAME_ROOT.rst
new file mode 100644
index 0000000..0388271
--- /dev/null
+++ b/Help/release/dev/find_package-PACKAGENAME_ROOT.rst
@@ -0,0 +1,7 @@
+find_package-PACKAGENAME_ROOT
+-----------------------------
+
+* The :command:`find_package` command now searches prefixes specified by
+  upper-case :variable:`<PACKAGENAME>_ROOT` CMake variables and upper-case
+  :envvar:`<PACKAGENAME>_ROOT` environment variables.
+  See policy :policy:`CMP0144`.
diff --git a/Help/variable/PackageName_ROOT.rst b/Help/variable/PackageName_ROOT.rst
index 6b17be3..8b728ba 100644
--- a/Help/variable/PackageName_ROOT.rst
+++ b/Help/variable/PackageName_ROOT.rst
@@ -14,3 +14,11 @@ This variable may hold a single prefix or a
 :ref:`semicolon-separated list <CMake Language Lists>` of multiple prefixes.
 
 See also the :envvar:`<PackageName>_ROOT` environment variable.
+
+.. variable:: <PACKAGENAME>_ROOT
+
+  .. versionadded:: 3.27
+
+  Calls to :command:`find_package(<PackageName>)` will also search in
+  prefixes specified by the upper-case ``<PACKAGENAME>_ROOT`` CMake
+  variable.  See policy :policy:`CMP0144`.
diff --git a/Source/cmFindPackageCommand.cxx b/Source/cmFindPackageCommand.cxx
index c1b82ab..5f1a2c5 100644
--- a/Source/cmFindPackageCommand.cxx
+++ b/Source/cmFindPackageCommand.cxx
@@ -975,35 +975,7 @@ bool cmFindPackageCommand::InitialPass(std::vector<std::string> const& args)
     }
   }
 
-  {
-    // Allocate a PACKAGE_ROOT_PATH for the current find_package call.
-    this->Makefile->FindPackageRootPathStack.emplace_back();
-    std::vector<std::string>& rootPaths =
-      this->Makefile->FindPackageRootPathStack.back();
-
-    // Add root paths from <PackageName>_ROOT CMake and environment variables,
-    // subject to CMP0074.
-    switch (this->Makefile->GetPolicyStatus(cmPolicies::CMP0074)) {
-      case cmPolicies::WARN:
-        this->Makefile->MaybeWarnCMP0074(this->Name);
-        CM_FALLTHROUGH;
-      case cmPolicies::OLD:
-        // OLD behavior is to ignore the <pkg>_ROOT variables.
-        break;
-      case cmPolicies::REQUIRED_IF_USED:
-      case cmPolicies::REQUIRED_ALWAYS:
-        this->Makefile->IssueMessage(
-          MessageType::FATAL_ERROR,
-          cmPolicies::GetRequiredPolicyError(cmPolicies::CMP0074));
-        break;
-      case cmPolicies::NEW: {
-        // NEW behavior is to honor the <pkg>_ROOT variables.
-        std::string const rootVar = this->Name + "_ROOT";
-        this->Makefile->GetDefExpandList(rootVar, rootPaths, false);
-        cmSystemTools::GetPath(rootPaths, rootVar.c_str());
-      } break;
-    }
-  }
+  this->PushFindPackageRootPathStack();
 
   this->SetModuleVariables(components, componentVarDefs);
 
@@ -1129,8 +1101,7 @@ bool cmFindPackageCommand::InitialPass(std::vector<std::string> const& args)
   // Restore original state of "_FIND_" variables set in SetModuleVariables()
   this->RestoreFindDefinitions();
 
-  // Pop the package stack
-  this->Makefile->FindPackageRootPathStack.pop_back();
+  this->PopFindPackageRootPathStack();
 
   if (!this->DebugBuffer.empty()) {
     this->DebugMessage(this->DebugBuffer);
@@ -1834,6 +1805,99 @@ void cmFindPackageCommand::AppendSuccessInformation()
   }
 }
 
+void cmFindPackageCommand::PushFindPackageRootPathStack()
+{
+  // Allocate a PACKAGE_ROOT_PATH for the current find_package call.
+  this->Makefile->FindPackageRootPathStack.emplace_back();
+  std::vector<std::string>& rootPaths =
+    this->Makefile->FindPackageRootPathStack.back();
+
+  // Add root paths from <PackageName>_ROOT CMake and environment variables,
+  // subject to CMP0074.
+  std::string const rootVar = this->Name + "_ROOT";
+  cmValue rootDef = this->Makefile->GetDefinition(rootVar);
+  if (rootDef && rootDef.IsEmpty()) {
+    rootDef = nullptr;
+  }
+  cm::optional<std::string> rootEnv = cmSystemTools::GetEnvVar(rootVar);
+  if (rootEnv && rootEnv->empty()) {
+    rootEnv = cm::nullopt;
+  }
+  switch (this->Makefile->GetPolicyStatus(cmPolicies::CMP0074)) {
+    case cmPolicies::WARN:
+      this->Makefile->MaybeWarnCMP0074(rootVar, rootDef, rootEnv);
+      CM_FALLTHROUGH;
+    case cmPolicies::OLD:
+      // OLD behavior is to ignore the <PackageName>_ROOT variables.
+      return;
+    case cmPolicies::REQUIRED_IF_USED:
+    case cmPolicies::REQUIRED_ALWAYS:
+      this->Makefile->IssueMessage(
+        MessageType::FATAL_ERROR,
+        cmPolicies::GetRequiredPolicyError(cmPolicies::CMP0074));
+      return;
+    case cmPolicies::NEW: {
+      // NEW behavior is to honor the <PackageName>_ROOT variables.
+    } break;
+  }
+
+  // Add root paths from <PACKAGENAME>_ROOT CMake and environment variables,
+  // if they are different than <PackageName>_ROOT, and subject to CMP0144.
+  std::string const rootVAR = cmSystemTools::UpperCase(rootVar);
+  cmValue rootDEF;
+  cm::optional<std::string> rootENV;
+  if (rootVAR != rootVar) {
+    rootDEF = this->Makefile->GetDefinition(rootVAR);
+    if (rootDEF && (rootDEF.IsEmpty() || rootDEF == rootDef)) {
+      rootDEF = nullptr;
+    }
+    rootENV = cmSystemTools::GetEnvVar(rootVAR);
+    if (rootENV && (rootENV->empty() || rootENV == rootEnv)) {
+      rootENV = cm::nullopt;
+    }
+  }
+
+  switch (this->Makefile->GetPolicyStatus(cmPolicies::CMP0144)) {
+    case cmPolicies::WARN:
+      this->Makefile->MaybeWarnCMP0144(rootVAR, rootDEF, rootENV);
+      CM_FALLTHROUGH;
+    case cmPolicies::OLD:
+      // OLD behavior is to ignore the <PACKAGENAME>_ROOT variables.
+      rootDEF = nullptr;
+      rootENV = cm::nullopt;
+      break;
+    case cmPolicies::REQUIRED_IF_USED:
+    case cmPolicies::REQUIRED_ALWAYS:
+      this->Makefile->IssueMessage(
+        MessageType::FATAL_ERROR,
+        cmPolicies::GetRequiredPolicyError(cmPolicies::CMP0144));
+      return;
+    case cmPolicies::NEW: {
+      // NEW behavior is to honor the <PACKAGENAME>_ROOT variables.
+    } break;
+  }
+
+  if (rootDef) {
+    cmExpandList(*rootDef, rootPaths);
+  }
+  if (rootDEF) {
+    cmExpandList(*rootDEF, rootPaths);
+  }
+  if (rootEnv) {
+    std::vector<std::string> p = cmSystemTools::SplitEnvPath(*rootEnv);
+    std::move(p.begin(), p.end(), std::back_inserter(rootPaths));
+  }
+  if (rootENV) {
+    std::vector<std::string> p = cmSystemTools::SplitEnvPath(*rootENV);
+    std::move(p.begin(), p.end(), std::back_inserter(rootPaths));
+  }
+}
+
+void cmFindPackageCommand::PopFindPackageRootPathStack()
+{
+  this->Makefile->FindPackageRootPathStack.pop_back();
+}
+
 void cmFindPackageCommand::ComputePrefixes()
 {
   this->FillPrefixesPackageRedirect();
diff --git a/Source/cmFindPackageCommand.h b/Source/cmFindPackageCommand.h
index 28e00a1..18684c9 100644
--- a/Source/cmFindPackageCommand.h
+++ b/Source/cmFindPackageCommand.h
@@ -125,6 +125,9 @@ private:
   void StoreVersionFound();
   void SetConfigDirCacheVariable(const std::string& value);
 
+  void PushFindPackageRootPathStack();
+  void PopFindPackageRootPathStack();
+
   void ComputePrefixes();
   void FillPrefixesPackageRedirect();
   void FillPrefixesPackageRoot();
diff --git a/Source/cmMakefile.cxx b/Source/cmMakefile.cxx
index d963a5a..2fc2974 100644
--- a/Source/cmMakefile.cxx
+++ b/Source/cmMakefile.cxx
@@ -208,32 +208,47 @@ bool cmMakefile::CheckCMP0037(std::string const& targetName,
   return true;
 }
 
-void cmMakefile::MaybeWarnCMP0074(std::string const& pkg)
+void cmMakefile::MaybeWarnCMP0074(std::string const& rootVar, cmValue rootDef,
+                                  cm::optional<std::string> const& rootEnv)
 {
-  // Warn if a <pkg>_ROOT variable we may use is set.
-  std::string const varName = pkg + "_ROOT";
-  cmValue var = this->GetDefinition(varName);
-  std::string env;
-  cmSystemTools::GetEnv(varName, env);
-
-  bool const haveVar = cmNonempty(var);
-  bool const haveEnv = !env.empty();
-  if ((haveVar || haveEnv) && this->WarnedCMP0074.insert(varName).second) {
+  // Warn if a <PackageName>_ROOT variable we may use is set.
+  if ((rootDef || rootEnv) && this->WarnedCMP0074.insert(rootVar).second) {
     std::ostringstream w;
     w << cmPolicies::GetPolicyWarning(cmPolicies::CMP0074) << "\n";
-    if (haveVar) {
-      w << "CMake variable " << varName << " is set to:\n"
-        << "  " << *var << "\n";
+    if (rootDef) {
+      w << "CMake variable " << rootVar << " is set to:\n"
+        << "  " << *rootDef << "\n";
     }
-    if (haveEnv) {
-      w << "Environment variable " << varName << " is set to:\n"
-        << "  " << env << "\n";
+    if (rootEnv) {
+      w << "Environment variable " << rootVar << " is set to:\n"
+        << "  " << *rootEnv << "\n";
     }
     w << "For compatibility, CMake is ignoring the variable.";
     this->IssueMessage(MessageType::AUTHOR_WARNING, w.str());
   }
 }
 
+void cmMakefile::MaybeWarnCMP0144(std::string const& rootVAR, cmValue rootDEF,
+                                  cm::optional<std::string> const& rootENV)
+{
+  // Warn if a <PACKAGENAME>_ROOT variable we may use is set.
+  if ((rootDEF || rootENV) && this->WarnedCMP0144.insert(rootVAR).second) {
+    std::ostringstream w;
+    w << cmPolicies::GetPolicyWarning(cmPolicies::CMP0144) << "\n";
+    if (rootDEF) {
+      w << "CMake variable " << rootVAR << " is set to:\n"
+        << "  " << *rootDEF << "\n";
+    }
+    if (rootENV) {
+      w << "Environment variable " << rootVAR << " is set to:\n"
+        << "  " << *rootENV << "\n";
+    }
+    w << "For compatibility, find_package is ignoring the variable, but "
+         "code in a .cmake module might still use it.";
+    this->IssueMessage(MessageType::AUTHOR_WARNING, w.str());
+  }
+}
+
 cmBTStringRange cmMakefile::GetIncludeDirectoriesEntries() const
 {
   return this->StateSnapshot.GetDirectory().GetIncludeDirectoriesEntries();
diff --git a/Source/cmMakefile.h b/Source/cmMakefile.h
index 7b19c97..3cf6e61 100644
--- a/Source/cmMakefile.h
+++ b/Source/cmMakefile.h
@@ -1011,7 +1011,10 @@ public:
 
   bool GetDebugFindPkgMode() const;
 
-  void MaybeWarnCMP0074(std::string const& pkg);
+  void MaybeWarnCMP0074(std::string const& rootVar, cmValue rootDef,
+                        cm::optional<std::string> const& rootEnv);
+  void MaybeWarnCMP0144(std::string const& rootVAR, cmValue rootDEF,
+                        cm::optional<std::string> const& rootENV);
   void MaybeWarnUninitialized(std::string const& variable,
                               const char* sourceFilename) const;
   bool IsProjectFile(const char* filename) const;
@@ -1189,6 +1192,7 @@ private:
   bool CheckSystemVars;
   bool CheckCMP0000;
   std::set<std::string> WarnedCMP0074;
+  std::set<std::string> WarnedCMP0144;
   bool IsSourceFileTryCompile;
   mutable bool SuppressSideEffects;
   ImportedTargetScope CurrentImportedTargetScope = ImportedTargetScope::Local;
diff --git a/Source/cmPolicies.h b/Source/cmPolicies.h
index 568eca3..1eca586 100644
--- a/Source/cmPolicies.h
+++ b/Source/cmPolicies.h
@@ -434,7 +434,10 @@ class cmMakefile;
          3, 25, 0, cmPolicies::WARN)                                          \
   SELECT(POLICY, CMP0143,                                                     \
          "Global property USE_FOLDERS treated as ON by default", 3, 26, 0,    \
-         cmPolicies::WARN)
+         cmPolicies::WARN)                                                    \
+  SELECT(POLICY, CMP0144,                                                     \
+         "find_package uses upper-case <PACKAGENAME>_ROOT variables.", 3, 27, \
+         0, cmPolicies::WARN)
 
 #define CM_SELECT_ID(F, A1, A2, A3, A4, A5, A6) F(A1)
 #define CM_FOR_EACH_POLICY_ID(POLICY)                                         \
diff --git a/Source/cmSystemTools.cxx b/Source/cmSystemTools.cxx
index 3d61270..1fb0079 100644
--- a/Source/cmSystemTools.cxx
+++ b/Source/cmSystemTools.cxx
@@ -1648,6 +1648,32 @@ std::string cmSystemTools::RelativeIfUnder(std::string const& top,
   return out;
 }
 
+cm::optional<std::string> cmSystemTools::GetEnvVar(std::string const& var)
+{
+  cm::optional<std::string> result;
+  {
+    std::string value;
+    if (cmSystemTools::GetEnv(var, value)) {
+      result = std::move(value);
+    }
+  }
+  return result;
+}
+
+std::vector<std::string> cmSystemTools::SplitEnvPath(std::string const& value)
+{
+#if defined(_WIN32) && !defined(__CYGWIN__)
+  static cm::string_view sep = ";"_s;
+#else
+  static cm::string_view sep = ":"_s;
+#endif
+  std::vector<std::string> paths = cmTokenize(value, sep);
+  for (std::string& p : paths) {
+    SystemTools::ConvertToUnixSlashes(p);
+  }
+  return paths;
+}
+
 #ifndef CMAKE_BOOTSTRAP
 bool cmSystemTools::UnsetEnv(const char* value)
 {
diff --git a/Source/cmSystemTools.h b/Source/cmSystemTools.h
index 09f2bf0..7d55d4b 100644
--- a/Source/cmSystemTools.h
+++ b/Source/cmSystemTools.h
@@ -399,6 +399,9 @@ public:
   static std::string RelativeIfUnder(std::string const& top,
                                      std::string const& in);
 
+  static cm::optional<std::string> GetEnvVar(std::string const& var);
+  static std::vector<std::string> SplitEnvPath(std::string const& value);
+
 #ifndef CMAKE_BOOTSTRAP
   /** Remove an environment variable */
   static bool UnsetEnv(const char* value);
diff --git a/Tests/RunCMake/find_package/CMP0144-NEW-CaseInsensitive-stderr.txt b/Tests/RunCMake/find_package/CMP0144-NEW-CaseInsensitive-stderr.txt
new file mode 100644
index 0000000..3ccd101
--- /dev/null
+++ b/Tests/RunCMake/find_package/CMP0144-NEW-CaseInsensitive-stderr.txt
@@ -0,0 +1,45 @@
+^----------
+FOO_ROOT     : ''
+ENV{FOO_ROOT}: ''
+
+find_package\(Foo\)
+FOO_TEST_FILE_FOO: FOO_TEST_FILE_FOO-NOTFOUND
+FOO_TEST_FILE_ZOT: FOO_TEST_FILE_ZOT-NOTFOUND
+FOO_TEST_PATH_FOO: FOO_TEST_PATH_FOO-NOTFOUND
+FOO_TEST_PATH_ZOT: FOO_TEST_PATH_ZOT-NOTFOUND
+FOO_TEST_PROG_FOO: FOO_TEST_PROG_FOO-NOTFOUND
+
+----------
+FOO_ROOT     : '<base>/foo/cmake_root'
+ENV{FOO_ROOT}: '<base>/foo/env_root'
+
+find_package\(Foo\)
+FOO_TEST_FILE_FOO: <base>/foo/cmake_root/include/foo.h
+FOO_TEST_FILE_ZOT: <base>/foo/cmake_root/include/zot/zot.h
+FOO_TEST_PATH_FOO: <base>/foo/cmake_root/include
+FOO_TEST_PATH_ZOT: <base>/foo/cmake_root/include/zot
+FOO_TEST_PROG_FOO: <base>/foo/cmake_root/bin/foo.exe
+
+----------
+FOO_ROOT     : '<base>/foo/cmake_root'
+ENV{FOO_ROOT}: ''
+
+find_package\(Foo\)
+FOO_TEST_FILE_FOO: <base>/foo/cmake_root/include/foo.h
+FOO_TEST_FILE_ZOT: <base>/foo/cmake_root/include/zot/zot.h
+FOO_TEST_PATH_FOO: <base>/foo/cmake_root/include
+FOO_TEST_PATH_ZOT: <base>/foo/cmake_root/include/zot
+FOO_TEST_PROG_FOO: <base>/foo/cmake_root/bin/foo.exe
+
+----------
+FOO_ROOT     : ''
+ENV{FOO_ROOT}: '<base>/foo/env_root'
+
+find_package\(Foo\)
+FOO_TEST_FILE_FOO: <base>/foo/env_root/include/foo.h
+FOO_TEST_FILE_ZOT: <base>/foo/env_root/include/zot/zot.h
+FOO_TEST_PATH_FOO: <base>/foo/env_root/include
+FOO_TEST_PATH_ZOT: <base>/foo/env_root/include/zot
+FOO_TEST_PROG_FOO: <base>/foo/env_root/bin/foo.exe
+
+----------$
diff --git a/Tests/RunCMake/find_package/CMP0144-NEW-CaseInsensitive.cmake b/Tests/RunCMake/find_package/CMP0144-NEW-CaseInsensitive.cmake
new file mode 100644
index 0000000..f0853ee
--- /dev/null
+++ b/Tests/RunCMake/find_package/CMP0144-NEW-CaseInsensitive.cmake
@@ -0,0 +1,3 @@
+cmake_policy(VERSION 3.26)
+cmake_policy(SET CMP0144 NEW)
+include(CMP0144-common.cmake)
diff --git a/Tests/RunCMake/find_package/CMP0144-NEW-CaseSensitive-stderr.txt b/Tests/RunCMake/find_package/CMP0144-NEW-CaseSensitive-stderr.txt
new file mode 100644
index 0000000..3ccd101
--- /dev/null
+++ b/Tests/RunCMake/find_package/CMP0144-NEW-CaseSensitive-stderr.txt
@@ -0,0 +1,45 @@
+^----------
+FOO_ROOT     : ''
+ENV{FOO_ROOT}: ''
+
+find_package\(Foo\)
+FOO_TEST_FILE_FOO: FOO_TEST_FILE_FOO-NOTFOUND
+FOO_TEST_FILE_ZOT: FOO_TEST_FILE_ZOT-NOTFOUND
+FOO_TEST_PATH_FOO: FOO_TEST_PATH_FOO-NOTFOUND
+FOO_TEST_PATH_ZOT: FOO_TEST_PATH_ZOT-NOTFOUND
+FOO_TEST_PROG_FOO: FOO_TEST_PROG_FOO-NOTFOUND
+
+----------
+FOO_ROOT     : '<base>/foo/cmake_root'
+ENV{FOO_ROOT}: '<base>/foo/env_root'
+
+find_package\(Foo\)
+FOO_TEST_FILE_FOO: <base>/foo/cmake_root/include/foo.h
+FOO_TEST_FILE_ZOT: <base>/foo/cmake_root/include/zot/zot.h
+FOO_TEST_PATH_FOO: <base>/foo/cmake_root/include
+FOO_TEST_PATH_ZOT: <base>/foo/cmake_root/include/zot
+FOO_TEST_PROG_FOO: <base>/foo/cmake_root/bin/foo.exe
+
+----------
+FOO_ROOT     : '<base>/foo/cmake_root'
+ENV{FOO_ROOT}: ''
+
+find_package\(Foo\)
+FOO_TEST_FILE_FOO: <base>/foo/cmake_root/include/foo.h
+FOO_TEST_FILE_ZOT: <base>/foo/cmake_root/include/zot/zot.h
+FOO_TEST_PATH_FOO: <base>/foo/cmake_root/include
+FOO_TEST_PATH_ZOT: <base>/foo/cmake_root/include/zot
+FOO_TEST_PROG_FOO: <base>/foo/cmake_root/bin/foo.exe
+
+----------
+FOO_ROOT     : ''
+ENV{FOO_ROOT}: '<base>/foo/env_root'
+
+find_package\(Foo\)
+FOO_TEST_FILE_FOO: <base>/foo/env_root/include/foo.h
+FOO_TEST_FILE_ZOT: <base>/foo/env_root/include/zot/zot.h
+FOO_TEST_PATH_FOO: <base>/foo/env_root/include
+FOO_TEST_PATH_ZOT: <base>/foo/env_root/include/zot
+FOO_TEST_PROG_FOO: <base>/foo/env_root/bin/foo.exe
+
+----------$
diff --git a/Tests/RunCMake/find_package/CMP0144-NEW-CaseSensitive.cmake b/Tests/RunCMake/find_package/CMP0144-NEW-CaseSensitive.cmake
new file mode 100644
index 0000000..f0853ee
--- /dev/null
+++ b/Tests/RunCMake/find_package/CMP0144-NEW-CaseSensitive.cmake
@@ -0,0 +1,3 @@
+cmake_policy(VERSION 3.26)
+cmake_policy(SET CMP0144 NEW)
+include(CMP0144-common.cmake)
diff --git a/Tests/RunCMake/find_package/CMP0144-OLD-CaseInsensitive-stderr.txt b/Tests/RunCMake/find_package/CMP0144-OLD-CaseInsensitive-stderr.txt
new file mode 100644
index 0000000..3274b82
--- /dev/null
+++ b/Tests/RunCMake/find_package/CMP0144-OLD-CaseInsensitive-stderr.txt
@@ -0,0 +1,45 @@
+^----------
+FOO_ROOT     : ''
+ENV{FOO_ROOT}: ''
+
+find_package\(Foo\)
+FOO_TEST_FILE_FOO: FOO_TEST_FILE_FOO-NOTFOUND
+FOO_TEST_FILE_ZOT: FOO_TEST_FILE_ZOT-NOTFOUND
+FOO_TEST_PATH_FOO: FOO_TEST_PATH_FOO-NOTFOUND
+FOO_TEST_PATH_ZOT: FOO_TEST_PATH_ZOT-NOTFOUND
+FOO_TEST_PROG_FOO: FOO_TEST_PROG_FOO-NOTFOUND
+
+----------
+FOO_ROOT     : '<base>/foo/cmake_root'
+ENV{FOO_ROOT}: '<base>/foo/env_root'
+
+find_package\(Foo\)
+FOO_TEST_FILE_FOO: <base>/foo/env_root/include/foo.h
+FOO_TEST_FILE_ZOT: <base>/foo/env_root/include/zot/zot.h
+FOO_TEST_PATH_FOO: <base>/foo/env_root/include
+FOO_TEST_PATH_ZOT: <base>/foo/env_root/include/zot
+FOO_TEST_PROG_FOO: <base>/foo/env_root/bin/foo.exe
+
+----------
+FOO_ROOT     : '<base>/foo/cmake_root'
+ENV{FOO_ROOT}: ''
+
+find_package\(Foo\)
+FOO_TEST_FILE_FOO: FOO_TEST_FILE_FOO-NOTFOUND
+FOO_TEST_FILE_ZOT: FOO_TEST_FILE_ZOT-NOTFOUND
+FOO_TEST_PATH_FOO: FOO_TEST_PATH_FOO-NOTFOUND
+FOO_TEST_PATH_ZOT: FOO_TEST_PATH_ZOT-NOTFOUND
+FOO_TEST_PROG_FOO: FOO_TEST_PROG_FOO-NOTFOUND
+
+----------
+FOO_ROOT     : ''
+ENV{FOO_ROOT}: '<base>/foo/env_root'
+
+find_package\(Foo\)
+FOO_TEST_FILE_FOO: <base>/foo/env_root/include/foo.h
+FOO_TEST_FILE_ZOT: <base>/foo/env_root/include/zot/zot.h
+FOO_TEST_PATH_FOO: <base>/foo/env_root/include
+FOO_TEST_PATH_ZOT: <base>/foo/env_root/include/zot
+FOO_TEST_PROG_FOO: <base>/foo/env_root/bin/foo.exe
+
+----------$
diff --git a/Tests/RunCMake/find_package/CMP0144-OLD-CaseInsensitive.cmake b/Tests/RunCMake/find_package/CMP0144-OLD-CaseInsensitive.cmake
new file mode 100644
index 0000000..f1560a9
--- /dev/null
+++ b/Tests/RunCMake/find_package/CMP0144-OLD-CaseInsensitive.cmake
@@ -0,0 +1,3 @@
+cmake_policy(VERSION 3.26)
+cmake_policy(SET CMP0144 OLD)
+include(CMP0144-common.cmake)
diff --git a/Tests/RunCMake/find_package/CMP0144-OLD-CaseSensitive-stderr.txt b/Tests/RunCMake/find_package/CMP0144-OLD-CaseSensitive-stderr.txt
new file mode 100644
index 0000000..c02a797
--- /dev/null
+++ b/Tests/RunCMake/find_package/CMP0144-OLD-CaseSensitive-stderr.txt
@@ -0,0 +1,45 @@
+^----------
+FOO_ROOT     : ''
+ENV{FOO_ROOT}: ''
+
+find_package\(Foo\)
+FOO_TEST_FILE_FOO: FOO_TEST_FILE_FOO-NOTFOUND
+FOO_TEST_FILE_ZOT: FOO_TEST_FILE_ZOT-NOTFOUND
+FOO_TEST_PATH_FOO: FOO_TEST_PATH_FOO-NOTFOUND
+FOO_TEST_PATH_ZOT: FOO_TEST_PATH_ZOT-NOTFOUND
+FOO_TEST_PROG_FOO: FOO_TEST_PROG_FOO-NOTFOUND
+
+----------
+FOO_ROOT     : '<base>/foo/cmake_root'
+ENV{FOO_ROOT}: '<base>/foo/env_root'
+
+find_package\(Foo\)
+FOO_TEST_FILE_FOO: FOO_TEST_FILE_FOO-NOTFOUND
+FOO_TEST_FILE_ZOT: FOO_TEST_FILE_ZOT-NOTFOUND
+FOO_TEST_PATH_FOO: FOO_TEST_PATH_FOO-NOTFOUND
+FOO_TEST_PATH_ZOT: FOO_TEST_PATH_ZOT-NOTFOUND
+FOO_TEST_PROG_FOO: FOO_TEST_PROG_FOO-NOTFOUND
+
+----------
+FOO_ROOT     : '<base>/foo/cmake_root'
+ENV{FOO_ROOT}: ''
+
+find_package\(Foo\)
+FOO_TEST_FILE_FOO: FOO_TEST_FILE_FOO-NOTFOUND
+FOO_TEST_FILE_ZOT: FOO_TEST_FILE_ZOT-NOTFOUND
+FOO_TEST_PATH_FOO: FOO_TEST_PATH_FOO-NOTFOUND
+FOO_TEST_PATH_ZOT: FOO_TEST_PATH_ZOT-NOTFOUND
+FOO_TEST_PROG_FOO: FOO_TEST_PROG_FOO-NOTFOUND
+
+----------
+FOO_ROOT     : ''
+ENV{FOO_ROOT}: '<base>/foo/env_root'
+
+find_package\(Foo\)
+FOO_TEST_FILE_FOO: FOO_TEST_FILE_FOO-NOTFOUND
+FOO_TEST_FILE_ZOT: FOO_TEST_FILE_ZOT-NOTFOUND
+FOO_TEST_PATH_FOO: FOO_TEST_PATH_FOO-NOTFOUND
+FOO_TEST_PATH_ZOT: FOO_TEST_PATH_ZOT-NOTFOUND
+FOO_TEST_PROG_FOO: FOO_TEST_PROG_FOO-NOTFOUND
+
+----------$
diff --git a/Tests/RunCMake/find_package/CMP0144-OLD-CaseSensitive.cmake b/Tests/RunCMake/find_package/CMP0144-OLD-CaseSensitive.cmake
new file mode 100644
index 0000000..f1560a9
--- /dev/null
+++ b/Tests/RunCMake/find_package/CMP0144-OLD-CaseSensitive.cmake
@@ -0,0 +1,3 @@
+cmake_policy(VERSION 3.26)
+cmake_policy(SET CMP0144 OLD)
+include(CMP0144-common.cmake)
diff --git a/Tests/RunCMake/find_package/CMP0144-WARN-CaseInsensitive-stderr.txt b/Tests/RunCMake/find_package/CMP0144-WARN-CaseInsensitive-stderr.txt
new file mode 100644
index 0000000..3540dc9
--- /dev/null
+++ b/Tests/RunCMake/find_package/CMP0144-WARN-CaseInsensitive-stderr.txt
@@ -0,0 +1,63 @@
+^----------
+FOO_ROOT     : ''
+ENV{FOO_ROOT}: ''
+
+find_package\(Foo\)
+FOO_TEST_FILE_FOO: FOO_TEST_FILE_FOO-NOTFOUND
+FOO_TEST_FILE_ZOT: FOO_TEST_FILE_ZOT-NOTFOUND
+FOO_TEST_PATH_FOO: FOO_TEST_PATH_FOO-NOTFOUND
+FOO_TEST_PATH_ZOT: FOO_TEST_PATH_ZOT-NOTFOUND
+FOO_TEST_PROG_FOO: FOO_TEST_PROG_FOO-NOTFOUND
+
+----------
+FOO_ROOT     : '<base>/foo/cmake_root'
+ENV{FOO_ROOT}: '<base>/foo/env_root'
++
+CMake Warning \(dev\) at CMP0144-common.cmake:[0-9]+ \(find_package\):
+  Policy CMP0144 is not set: find_package uses upper-case <PACKAGENAME>_ROOT
+  variables.  Run "cmake --help-policy CMP0144" for policy details\.  Use the
+  cmake_policy command to set the policy and suppress this warning\.
+
+  CMake variable FOO_ROOT is set to:
+
+    [^
+]*/Tests/RunCMake/find_package/PackageRoot/foo/cmake_root
+
+  For compatibility, find_package is ignoring the variable, but code in a
+  \.cmake module might still use it\.
+Call Stack \(most recent call first\):
+  CMP0144-common.cmake:[0-9]+ \(RunTestCase\)
+  CMP0144-WARN-CaseInsensitive.cmake:[0-9]+ \(include\)
+  CMakeLists.txt:[0-9]+ \(include\)
+This warning is for project developers.  Use -Wno-dev to suppress it.
++
+find_package\(Foo\)
+FOO_TEST_FILE_FOO: <base>/foo/env_root/include/foo.h
+FOO_TEST_FILE_ZOT: <base>/foo/env_root/include/zot/zot.h
+FOO_TEST_PATH_FOO: <base>/foo/env_root/include
+FOO_TEST_PATH_ZOT: <base>/foo/env_root/include/zot
+FOO_TEST_PROG_FOO: <base>/foo/env_root/bin/foo.exe
+
+----------
+FOO_ROOT     : '<base>/foo/cmake_root'
+ENV{FOO_ROOT}: ''
+
+find_package\(Foo\)
+FOO_TEST_FILE_FOO: FOO_TEST_FILE_FOO-NOTFOUND
+FOO_TEST_FILE_ZOT: FOO_TEST_FILE_ZOT-NOTFOUND
+FOO_TEST_PATH_FOO: FOO_TEST_PATH_FOO-NOTFOUND
+FOO_TEST_PATH_ZOT: FOO_TEST_PATH_ZOT-NOTFOUND
+FOO_TEST_PROG_FOO: FOO_TEST_PROG_FOO-NOTFOUND
+
+----------
+FOO_ROOT     : ''
+ENV{FOO_ROOT}: '<base>/foo/env_root'
+
+find_package\(Foo\)
+FOO_TEST_FILE_FOO: <base>/foo/env_root/include/foo.h
+FOO_TEST_FILE_ZOT: <base>/foo/env_root/include/zot/zot.h
+FOO_TEST_PATH_FOO: <base>/foo/env_root/include
+FOO_TEST_PATH_ZOT: <base>/foo/env_root/include/zot
+FOO_TEST_PROG_FOO: <base>/foo/env_root/bin/foo.exe
+
+----------$
diff --git a/Tests/RunCMake/find_package/CMP0144-WARN-CaseInsensitive.cmake b/Tests/RunCMake/find_package/CMP0144-WARN-CaseInsensitive.cmake
new file mode 100644
index 0000000..10f6b66
--- /dev/null
+++ b/Tests/RunCMake/find_package/CMP0144-WARN-CaseInsensitive.cmake
@@ -0,0 +1,3 @@
+cmake_policy(VERSION 3.26)
+# (do not set CMP0144)
+include(CMP0144-common.cmake)
diff --git a/Tests/RunCMake/find_package/CMP0144-WARN-CaseSensitive-Mixed-stderr.txt b/Tests/RunCMake/find_package/CMP0144-WARN-CaseSensitive-Mixed-stderr.txt
new file mode 100644
index 0000000..3ccd101
--- /dev/null
+++ b/Tests/RunCMake/find_package/CMP0144-WARN-CaseSensitive-Mixed-stderr.txt
@@ -0,0 +1,45 @@
+^----------
+FOO_ROOT     : ''
+ENV{FOO_ROOT}: ''
+
+find_package\(Foo\)
+FOO_TEST_FILE_FOO: FOO_TEST_FILE_FOO-NOTFOUND
+FOO_TEST_FILE_ZOT: FOO_TEST_FILE_ZOT-NOTFOUND
+FOO_TEST_PATH_FOO: FOO_TEST_PATH_FOO-NOTFOUND
+FOO_TEST_PATH_ZOT: FOO_TEST_PATH_ZOT-NOTFOUND
+FOO_TEST_PROG_FOO: FOO_TEST_PROG_FOO-NOTFOUND
+
+----------
+FOO_ROOT     : '<base>/foo/cmake_root'
+ENV{FOO_ROOT}: '<base>/foo/env_root'
+
+find_package\(Foo\)
+FOO_TEST_FILE_FOO: <base>/foo/cmake_root/include/foo.h
+FOO_TEST_FILE_ZOT: <base>/foo/cmake_root/include/zot/zot.h
+FOO_TEST_PATH_FOO: <base>/foo/cmake_root/include
+FOO_TEST_PATH_ZOT: <base>/foo/cmake_root/include/zot
+FOO_TEST_PROG_FOO: <base>/foo/cmake_root/bin/foo.exe
+
+----------
+FOO_ROOT     : '<base>/foo/cmake_root'
+ENV{FOO_ROOT}: ''
+
+find_package\(Foo\)
+FOO_TEST_FILE_FOO: <base>/foo/cmake_root/include/foo.h
+FOO_TEST_FILE_ZOT: <base>/foo/cmake_root/include/zot/zot.h
+FOO_TEST_PATH_FOO: <base>/foo/cmake_root/include
+FOO_TEST_PATH_ZOT: <base>/foo/cmake_root/include/zot
+FOO_TEST_PROG_FOO: <base>/foo/cmake_root/bin/foo.exe
+
+----------
+FOO_ROOT     : ''
+ENV{FOO_ROOT}: '<base>/foo/env_root'
+
+find_package\(Foo\)
+FOO_TEST_FILE_FOO: <base>/foo/env_root/include/foo.h
+FOO_TEST_FILE_ZOT: <base>/foo/env_root/include/zot/zot.h
+FOO_TEST_PATH_FOO: <base>/foo/env_root/include
+FOO_TEST_PATH_ZOT: <base>/foo/env_root/include/zot
+FOO_TEST_PROG_FOO: <base>/foo/env_root/bin/foo.exe
+
+----------$
diff --git a/Tests/RunCMake/find_package/CMP0144-WARN-CaseSensitive-Mixed.cmake b/Tests/RunCMake/find_package/CMP0144-WARN-CaseSensitive-Mixed.cmake
new file mode 100644
index 0000000..10f6b66
--- /dev/null
+++ b/Tests/RunCMake/find_package/CMP0144-WARN-CaseSensitive-Mixed.cmake
@@ -0,0 +1,3 @@
+cmake_policy(VERSION 3.26)
+# (do not set CMP0144)
+include(CMP0144-common.cmake)
diff --git a/Tests/RunCMake/find_package/CMP0144-WARN-CaseSensitive-stderr.txt b/Tests/RunCMake/find_package/CMP0144-WARN-CaseSensitive-stderr.txt
new file mode 100644
index 0000000..b828f05
--- /dev/null
+++ b/Tests/RunCMake/find_package/CMP0144-WARN-CaseSensitive-stderr.txt
@@ -0,0 +1,68 @@
+^----------
+FOO_ROOT     : ''
+ENV{FOO_ROOT}: ''
+
+find_package\(Foo\)
+FOO_TEST_FILE_FOO: FOO_TEST_FILE_FOO-NOTFOUND
+FOO_TEST_FILE_ZOT: FOO_TEST_FILE_ZOT-NOTFOUND
+FOO_TEST_PATH_FOO: FOO_TEST_PATH_FOO-NOTFOUND
+FOO_TEST_PATH_ZOT: FOO_TEST_PATH_ZOT-NOTFOUND
+FOO_TEST_PROG_FOO: FOO_TEST_PROG_FOO-NOTFOUND
+
+----------
+FOO_ROOT     : '<base>/foo/cmake_root'
+ENV{FOO_ROOT}: '<base>/foo/env_root'
++
+CMake Warning \(dev\) at CMP0144-common.cmake:[0-9]+ \(find_package\):
+  Policy CMP0144 is not set: find_package uses upper-case <PACKAGENAME>_ROOT
+  variables.  Run "cmake --help-policy CMP0144" for policy details\.  Use the
+  cmake_policy command to set the policy and suppress this warning\.
+
+  CMake variable FOO_ROOT is set to:
+
+    [^
+]*/Tests/RunCMake/find_package/PackageRoot/foo/cmake_root
+
+  Environment variable FOO_ROOT is set to:
+
+    [^
+]*/Tests/RunCMake/find_package/PackageRoot/foo/env_root
+
+  For compatibility, find_package is ignoring the variable, but code in a
+  \.cmake module might still use it\.
+Call Stack \(most recent call first\):
+  CMP0144-common.cmake:[0-9]+ \(RunTestCase\)
+  CMP0144-WARN-CaseSensitive.cmake:[0-9]+ \(include\)
+  CMakeLists.txt:[0-9]+ \(include\)
+This warning is for project developers.  Use -Wno-dev to suppress it.
++
+find_package\(Foo\)
+FOO_TEST_FILE_FOO: FOO_TEST_FILE_FOO-NOTFOUND
+FOO_TEST_FILE_ZOT: FOO_TEST_FILE_ZOT-NOTFOUND
+FOO_TEST_PATH_FOO: FOO_TEST_PATH_FOO-NOTFOUND
+FOO_TEST_PATH_ZOT: FOO_TEST_PATH_ZOT-NOTFOUND
+FOO_TEST_PROG_FOO: FOO_TEST_PROG_FOO-NOTFOUND
+
+----------
+FOO_ROOT     : '<base>/foo/cmake_root'
+ENV{FOO_ROOT}: ''
+
+find_package\(Foo\)
+FOO_TEST_FILE_FOO: FOO_TEST_FILE_FOO-NOTFOUND
+FOO_TEST_FILE_ZOT: FOO_TEST_FILE_ZOT-NOTFOUND
+FOO_TEST_PATH_FOO: FOO_TEST_PATH_FOO-NOTFOUND
+FOO_TEST_PATH_ZOT: FOO_TEST_PATH_ZOT-NOTFOUND
+FOO_TEST_PROG_FOO: FOO_TEST_PROG_FOO-NOTFOUND
+
+----------
+FOO_ROOT     : ''
+ENV{FOO_ROOT}: '<base>/foo/env_root'
+
+find_package\(Foo\)
+FOO_TEST_FILE_FOO: FOO_TEST_FILE_FOO-NOTFOUND
+FOO_TEST_FILE_ZOT: FOO_TEST_FILE_ZOT-NOTFOUND
+FOO_TEST_PATH_FOO: FOO_TEST_PATH_FOO-NOTFOUND
+FOO_TEST_PATH_ZOT: FOO_TEST_PATH_ZOT-NOTFOUND
+FOO_TEST_PROG_FOO: FOO_TEST_PROG_FOO-NOTFOUND
+
+----------$
diff --git a/Tests/RunCMake/find_package/CMP0144-WARN-CaseSensitive.cmake b/Tests/RunCMake/find_package/CMP0144-WARN-CaseSensitive.cmake
new file mode 100644
index 0000000..10f6b66
--- /dev/null
+++ b/Tests/RunCMake/find_package/CMP0144-WARN-CaseSensitive.cmake
@@ -0,0 +1,3 @@
+cmake_policy(VERSION 3.26)
+# (do not set CMP0144)
+include(CMP0144-common.cmake)
diff --git a/Tests/RunCMake/find_package/CMP0144-common.cmake b/Tests/RunCMake/find_package/CMP0144-common.cmake
new file mode 100644
index 0000000..58eccca
--- /dev/null
+++ b/Tests/RunCMake/find_package/CMP0144-common.cmake
@@ -0,0 +1,78 @@
+# (includer selects CMP0144)
+list(INSERT CMAKE_MODULE_PATH 0 ${CMAKE_CURRENT_SOURCE_DIR}/PackageRoot)
+set(PackageRoot_BASE ${CMAKE_CURRENT_SOURCE_DIR}/PackageRoot)
+
+function(PrintPath label path)
+  string(REPLACE "${PackageRoot_BASE}" "<base>" out "${path}")
+  message("${label} ${out}")
+endfunction()
+
+macro(RunTestCase)
+  message("----------")
+  PrintPath("FOO_ROOT     :" "'${FOO_ROOT}'")
+  PrintPath("ENV{FOO_ROOT}:" "'$ENV{FOO_ROOT}'")
+  message("")
+
+  find_package(Foo)
+  message("find_package(Foo)")
+  PrintPath("FOO_TEST_FILE_FOO:" "${FOO_TEST_FILE_FOO}")
+  PrintPath("FOO_TEST_FILE_ZOT:" "${FOO_TEST_FILE_ZOT}")
+  PrintPath("FOO_TEST_PATH_FOO:" "${FOO_TEST_PATH_FOO}")
+  PrintPath("FOO_TEST_PATH_ZOT:" "${FOO_TEST_PATH_ZOT}")
+  PrintPath("FOO_TEST_PROG_FOO:" "${FOO_TEST_PROG_FOO}")
+  message("")
+
+  unset(FOO_ROOT)
+  unset(ENV{FOO_ROOT})
+  if(NOT CMAKE_HOST_WIN32)
+    unset(Foo_ROOT)
+    unset(ENV{Foo_ROOT})
+  endif()
+  unset(FOO_TEST_FILE_FOO)
+  unset(FOO_TEST_FILE_ZOT)
+  unset(FOO_TEST_PATH_FOO)
+  unset(FOO_TEST_PATH_ZOT)
+  unset(FOO_TEST_PROG_FOO)
+  unset(FOO_TEST_FILE_FOO CACHE)
+  unset(FOO_TEST_FILE_ZOT CACHE)
+  unset(FOO_TEST_PATH_FOO CACHE)
+  unset(FOO_TEST_PATH_ZOT CACHE)
+  unset(FOO_TEST_PROG_FOO CACHE)
+endmacro()
+
+RunTestCase()
+
+set(FOO_ROOT      ${PackageRoot_BASE}/foo/cmake_root)
+set(ENV{FOO_ROOT} ${PackageRoot_BASE}/foo/env_root)
+if(RunCMake_TEST MATCHES "CaseSensitive")
+  if(RunCMake_TEST STREQUAL "CMP0144-WARN-CaseSensitive-Mixed")
+    set(Foo_ROOT      "${FOO_ROOT}")
+    set(ENV{Foo_ROOT} "$ENV{FOO_ROOT}")
+  else()
+    set(Foo_ROOT      ${PackageRoot_BASE}/does_not_exist)
+    set(ENV{Foo_ROOT} ${PackageRoot_BASE}/does_not_exist)
+  endif()
+endif()
+RunTestCase()
+
+set(FOO_ROOT      ${PackageRoot_BASE}/foo/cmake_root)
+if(RunCMake_TEST MATCHES "CaseSensitive")
+  if(RunCMake_TEST STREQUAL "CMP0144-WARN-CaseSensitive-Mixed")
+    set(Foo_ROOT      "${FOO_ROOT}")
+  else()
+    set(Foo_ROOT      ${PackageRoot_BASE}/does_not_exist)
+  endif()
+endif()
+RunTestCase()
+
+set(ENV{FOO_ROOT} ${PackageRoot_BASE}/foo/env_root)
+if(RunCMake_TEST MATCHES "CaseSensitive")
+  if(RunCMake_TEST STREQUAL "CMP0144-WARN-CaseSensitive-Mixed")
+    set(ENV{Foo_ROOT} "$ENV{FOO_ROOT}")
+  else()
+    set(ENV{Foo_ROOT} ${PackageRoot_BASE}/does_not_exist)
+  endif()
+endif()
+RunTestCase()
+
+message("----------")
diff --git a/Tests/RunCMake/find_package/RunCMakeTest.cmake b/Tests/RunCMake/find_package/RunCMakeTest.cmake
index fa41fc1..e7e3a0b 100644
--- a/Tests/RunCMake/find_package/RunCMakeTest.cmake
+++ b/Tests/RunCMake/find_package/RunCMakeTest.cmake
@@ -55,6 +55,17 @@ run_cmake(REGISTRY_VIEW-no-view)
 run_cmake(REGISTRY_VIEW-wrong-view)
 run_cmake(REGISTRY_VIEW-propagated)
 
+if(CMAKE_HOST_WIN32)
+  run_cmake(CMP0144-WARN-CaseInsensitive)
+  run_cmake(CMP0144-OLD-CaseInsensitive)
+  run_cmake(CMP0144-NEW-CaseInsensitive)
+else()
+  run_cmake(CMP0144-WARN-CaseSensitive)
+  run_cmake(CMP0144-WARN-CaseSensitive-Mixed)
+  run_cmake(CMP0144-OLD-CaseSensitive)
+  run_cmake(CMP0144-NEW-CaseSensitive)
+endif()
+
 file(
     GLOB SearchPaths_TEST_CASE_LIST
     LIST_DIRECTORIES TRUE