find_package: Implement UNWIND_INCLUDE

This implements a limited exception mechanism for find_package() via
the UNWIND_INCLUDE keyword.

When package discovery via find_package(UNWIND_INCLUDE) fails the
StateSnapshot is updated to an UNWINDING state. In this state further
calls to find_package() and include() are forbidden. While in the
UNWINDING state, the include() command immediately calls
SetReturnInvoked() whenever it is reached.

The UNWINDING state is reset when a parent call to find_package() is
reached.

Fixes: #26897

Help/command/find_package.rst

@@ -141,7 +141,8 @@ Basic Signature
                [REGISTRY_VIEW  (64|32|64_32|32_64|HOST|TARGET|BOTH)]
                [GLOBAL]
                [NO_POLICY_SCOPE]
-               [BYPASS_PROVIDER])
+               [BYPASS_PROVIDER]
+               [UNWIND_INCLUDE])
 
 The basic signature is supported by both Module and Config modes.
 The ``MODULE`` keyword implies that only Module mode can be used to find
@@ -249,6 +250,21 @@ of the ``NO_POLICY_SCOPE`` option.
   itself.  Future versions of CMake may detect attempts to use this keyword
   from places other than a dependency provider and halt with a fatal error.
 
+.. versionadded:: 4.2
+  The ``UNWIND_INCLUDE`` keyword is only allowed when ``find_package()`` is
+  being called within a parent call to ``find_package()``. When a call to
+  ``find_package(UNWIND_INCLUDE)`` fails to find the desired package, it begins
+  an "unwind" state. In this state further calls to ``find_package()`` and
+  :command:`include()` are forbidden, and all parent :command:`include()`
+  commands will immediately invoke :command:`return()` when their scope is
+  reached. This "unwinding" will continue until the parent ``find_package()``
+  is returned to.
+
+  ``UNWIND_INCLUDE`` is only intended to be used by calls to ``find_package()``
+  generated by :command:`install(EXPORT_PACKAGE_DEPENDENCIES)`, but may be
+  useful to those who wish to manually manage their dependencies in a similar
+  manner.
+
 .. _`full signature`:
 
 Full Signature

Help/release/dev/find-package-UNWIND_INCLUDE.rst

@@ -0,0 +1,6 @@
+find-package-UNWIND_INCLUDE
+---------------------------
+
+* The :command:`find_package()` command gained a new ``UNWIND_INCLUDE`` option
+  to enable immediate :command:`return` from :command:`include()` commands
+  after a failure to discover a transitive dependency.

Source/cmFindPackageCommand.cxx

@@ -630,6 +630,12 @@ bool cmFindPackageCommand::InitialPass(std::vector<std::string> const& args)
     return false;
   }
 
+  if (this->Makefile->GetStateSnapshot().GetUnwindState() ==
+      cmStateEnums::UNWINDING) {
+    this->SetError("called while already in an UNWIND state");
+    return false;
+  }
+
   // Lookup required version of CMake.
   if (cmValue const rv =
         this->Makefile->GetDefinition("CMAKE_MINIMUM_REQUIRED_VERSION")) {
@@ -839,6 +845,14 @@ bool cmFindPackageCommand::InitialPass(std::vector<std::string> const& args)
           cmStrCat("given invalid value for REGISTRY_VIEW: ", args[i]));
         return false;
       }
+    } else if (args[i] == "UNWIND_INCLUDE") {
+      if (this->Makefile->GetStateSnapshot().GetUnwindType() !=
+          cmStateEnums::CAN_UNWIND) {
+        this->SetError("called with UNWIND_INCLUDE in an invalid context");
+        return false;
+      }
+      this->ScopeUnwind = true;
+      doing = DoingNone;
     } else if (this->CheckCommonArgument(args[i])) {
       configArgs.push_back(i);
       doing = DoingNone;
@@ -1053,8 +1067,18 @@ bool cmFindPackageCommand::InitialPass(std::vector<std::string> const& args)
       this->VersionMaxPatch, this->VersionMaxTweak);
   }
 
-  return this->FindPackage(this->BypassProvider ? std::vector<std::string>{}
-                                                : args);
+  bool result = this->FindPackage(
+    this->BypassProvider ? std::vector<std::string>{} : args);
+
+  std::string const foundVar = cmStrCat(this->Name, "_FOUND");
+  bool const isFound = this->Makefile->IsOn(foundVar) ||
+    this->Makefile->IsOn(cmSystemTools::UpperCase(foundVar));
+
+  if (this->ScopeUnwind && (!result || !isFound)) {
+    this->Makefile->GetStateSnapshot().SetUnwindState(cmStateEnums::UNWINDING);
+  }
+
+  return result;
 }
 
 bool cmFindPackageCommand::FindPackage(
@@ -2047,12 +2071,24 @@ bool cmFindPackageCommand::ReadListFile(std::string const& f,
   ITScope scope = this->GlobalScope ? ITScope::Global : ITScope::Local;
   cmMakefile::SetGlobalTargetImportScope globScope(this->Makefile, scope);
 
-  if (this->Makefile->ReadDependentFile(f, noPolicyScope)) {
-    return true;
+  auto oldUnwind = this->Makefile->GetStateSnapshot().GetUnwindType();
+
+  // This allows child snapshots to inherit the CAN_UNWIND state from us, we'll
+  // reset it immediately after the dependent file is done
+  this->Makefile->GetStateSnapshot().SetUnwindType(cmStateEnums::CAN_UNWIND);
+  bool result = this->Makefile->ReadDependentFile(f, noPolicyScope);
+
+  this->Makefile->GetStateSnapshot().SetUnwindType(oldUnwind);
+  this->Makefile->GetStateSnapshot().SetUnwindState(
+    cmStateEnums::NOT_UNWINDING);
+
+  if (!result) {
+    std::string const e =
+      cmStrCat("Error reading CMake code from \"", f, "\".");
+    this->SetError(e);
   }
-  std::string const e = cmStrCat("Error reading CMake code from \"", f, "\".");
-  this->SetError(e);
-  return false;
+
+  return result;
 }
 
 bool cmFindPackageCommand::ReadPackage()

Source/cmFindPackageCommand.h

@@ -276,6 +276,7 @@ private:
   bool PolicyScope = true;
   bool GlobalScope = false;
   bool RegistryViewDefined = false;
+  bool ScopeUnwind = false;
   std::string LibraryArchitecture;
   std::vector<std::string> Names;
   std::set<std::string> IgnoredPaths;

Source/cmIncludeCommand.cxx

@@ -10,6 +10,8 @@
 #include "cmMakefile.h"
 #include "cmMessageType.h"
 #include "cmPolicies.h"
+#include "cmStateSnapshot.h"
+#include "cmStateTypes.h"
 #include "cmStringAlgorithms.h"
 #include "cmSystemTools.h"
 
@@ -38,6 +40,13 @@ bool cmIncludeCommand(std::vector<std::string> const& args,
                     "include() only takes one file.");
     return false;
   }
+
+  if (status.GetMakefile().GetStateSnapshot().GetUnwindState() ==
+      cmStateEnums::UNWINDING) {
+    status.SetError("called while already in an UNWIND state");
+    return false;
+  }
+
   bool optional = false;
   bool noPolicyScope = false;
   std::string fname = args[0];
@@ -166,5 +175,22 @@ bool cmIncludeCommand(std::vector<std::string> const& args,
     status.SetError(m);
     return false;
   }
+
+  if (status.GetMakefile().GetStateSnapshot().GetUnwindState() ==
+      cmStateEnums::UNWINDING) {
+
+    if (status.GetMakefile().GetStateSnapshot().GetUnwindType() !=
+        cmStateEnums::CAN_UNWIND) {
+      std::string m = cmStrCat("requested file is attempting to unwind the "
+                               "stack in an invalid context:\n ",
+                               fname);
+      status.SetError(m);
+      cmSystemTools::SetFatalErrorOccurred();
+      return false;
+    }
+
+    status.SetReturnInvoked();
+  }
+
   return true;
 }

Source/cmState.cxx

@@ -1030,6 +1030,7 @@ cmStateSnapshot cmState::Pop(cmStateSnapshot const& originSnapshot)
   prevPos->LinkDirectoriesPosition =
     prevPos->BuildSystemDirectory->LinkDirectories.size();
   prevPos->BuildSystemDirectory->CurrentScope = prevPos;
+  prevPos->UnwindState = pos->UnwindState;
 
   if (!pos->Keep && this->SnapshotData.IsLast(pos)) {
     if (pos->Vars != prevPos->Vars) {

Source/cmStatePrivate.h

@@ -34,6 +34,8 @@ struct cmStateDetail::SnapshotDataType
   cmLinkedTree<cmStateDetail::PolicyStackEntry>::iterator PolicyRoot;
   cmLinkedTree<cmStateDetail::PolicyStackEntry>::iterator PolicyScope;
   cmStateEnums::SnapshotType SnapshotType;
+  cmStateEnums::SnapshotUnwindType UnwindType = cmStateEnums::NO_UNWIND;
+  cmStateEnums::SnapshotUnwindState UnwindState = cmStateEnums::NOT_UNWINDING;
   bool Keep;
   cmLinkedTree<std::string>::iterator ExecutionListFile;
   cmLinkedTree<cmStateDetail::BuildsystemDirectoryStateType>::iterator

Source/cmStateSnapshot.cxx

@@ -50,6 +50,26 @@ cmStateEnums::SnapshotType cmStateSnapshot::GetType() const
   return this->Position->SnapshotType;
 }
 
+cmStateEnums::SnapshotUnwindType cmStateSnapshot::GetUnwindType() const
+{
+  return this->Position->UnwindType;
+}
+
+void cmStateSnapshot::SetUnwindType(cmStateEnums::SnapshotUnwindType type)
+{
+  this->Position->UnwindType = type;
+}
+
+cmStateEnums::SnapshotUnwindState cmStateSnapshot::GetUnwindState() const
+{
+  return this->Position->UnwindState;
+}
+
+void cmStateSnapshot::SetUnwindState(cmStateEnums::SnapshotUnwindState state)
+{
+  this->Position->UnwindState = state;
+}
+
 void cmStateSnapshot::SetListFile(std::string const& listfile)
 {
   *this->Position->ExecutionListFile = listfile;

Source/cmStateSnapshot.h

@@ -44,6 +44,12 @@ public:
   cmStateSnapshot GetCallStackBottom() const;
   cmStateEnums::SnapshotType GetType() const;
 
+  cmStateEnums::SnapshotUnwindType GetUnwindType() const;
+  void SetUnwindType(cmStateEnums::SnapshotUnwindType type);
+
+  cmStateEnums::SnapshotUnwindState GetUnwindState() const;
+  void SetUnwindState(cmStateEnums::SnapshotUnwindState state);
+
   void SetPolicy(cmPolicies::PolicyID id, cmPolicies::PolicyStatus status);
   cmPolicies::PolicyStatus GetPolicy(cmPolicies::PolicyID id,
                                      bool parent_scope = false) const;

Source/cmStateTypes.h

@@ -29,6 +29,18 @@ enum SnapshotType
   VariableScopeType
 };
 
+enum SnapshotUnwindType
+{
+  NO_UNWIND,
+  CAN_UNWIND
+};
+
+enum SnapshotUnwindState
+{
+  NOT_UNWINDING,
+  UNWINDING
+};
+
 // There are multiple overlapping ranges represented here. Be aware that adding
 // a value to this enumeration may cause failures in numerous places which
 // assume details about the ordering.

Tests/RunCMake/find_package/RunCMakeTest.cmake

@@ -48,6 +48,14 @@ run_cmake(RequiredVarOptional)
 run_cmake(RequiredVarNested)
 run_cmake(FindRootPathAndPrefixPathAreEqual)
 run_cmake(SetFoundFALSE)
+run_cmake(UnwindIncludeBlock)
+run_cmake(UnwindIncludeFunction)
+run_cmake(UnwindIncludeInvalidContext)
+run_cmake(UnwindIncludeInvalidFindPackage)
+run_cmake(UnwindIncludeInvalidInclude)
+run_cmake(UnwindIncludeNoUnwind)
+run_cmake(UnwindIncludeOnly)
+run_cmake(UnwindIncludeSecondary)
 run_cmake(WrongVersion)
 run_cmake(WrongVersionConfig)
 run_cmake(CMP0084-OLD)

Tests/RunCMake/find_package/UnwindInclude/NoUnwind.cmake

@@ -0,0 +1,2 @@
+find_package(SecondarySuccessful UNWIND_INCLUDE)
+include(${CMAKE_CURRENT_LIST_DIR}/NoOp.cmake)

Tests/RunCMake/find_package/UnwindInclude/PrimaryUnwindConfig.cmake

@@ -0,0 +1,2 @@
+include(${CMAKE_CURRENT_LIST_DIR}/${UNWIND_TARGET}.cmake)
+set(PrimaryUnwind_FOUND true)

Tests/RunCMake/find_package/UnwindInclude/SecondarySuccessfulConfig.cmake

@@ -0,0 +1 @@
+set(SecondarySuccessful_FOUND true)

Tests/RunCMake/find_package/UnwindInclude/SecondaryUnwindConfig.cmake

@@ -0,0 +1 @@
+set(SecondaryUnwind_FOUND false)

Tests/RunCMake/find_package/UnwindInclude/UnwindBlock.cmake

@@ -0,0 +1,14 @@
+set(RunCMake_TEST_FAILED "Failed to observe side effects of block() scopes during unwind")
+
+block()
+  find_package(foo UNWIND_INCLUDE)
+endblock()
+
+block(PROPAGATE BLOCK_RUN PrimaryUnwind_FOUND)
+  set(BLOCK_RUN true)
+  set(PrimaryUnwind_FOUND false)
+endblock()
+
+if(BLOCK_RUN)
+  set(RunCMake_TEST_FAILED)
+endif()

Tests/RunCMake/find_package/UnwindInclude/UnwindFunction.cmake

@@ -0,0 +1,20 @@
+cmake_policy(SET CMP0140 NEW)
+
+function(f)
+  find_package(foo UNWIND_INCLUDE)
+endfunction()
+
+function(g)
+  set(FUNC_CALLED true)
+  set(PrimaryUnwind_FOUND false)
+  return(PROPAGATE func_called PrimaryUnwind_FOUND)
+endfunction()
+
+set(RunCMake_TEST_FAILED "Failed to observe side effects of function() calls during unwind")
+
+f()
+g()
+
+if(FUNC_CALLED)
+  set(RunCMake_TEST_FAILED)
+endif()

Tests/RunCMake/find_package/UnwindInclude/UnwindInvalidFindPackage.cmake

@@ -0,0 +1,2 @@
+find_package(foo UNWIND_INCLUDE)
+find_package(bar)

Tests/RunCMake/find_package/UnwindInclude/UnwindInvalidInclude.cmake

@@ -0,0 +1,2 @@
+find_package(foo UNWIND_INCLUDE)
+include(${CMAKE_CURRENT_LIST_DIR}/NoOp.cmake)

Tests/RunCMake/find_package/UnwindInclude/UnwindOnly.cmake

@@ -0,0 +1,2 @@
+find_package(foo UNWIND_INCLUDE)
+set(PrimaryUnwind_FOUND false)

Tests/RunCMake/find_package/UnwindInclude/UnwindSecondary.cmake

@@ -0,0 +1,2 @@
+find_package(SecondaryUnwind UNWIND_INCLUDE)
+set(PrimaryUnwind_FOUND false)

Tests/RunCMake/find_package/UnwindIncludeBlock-stderr.txt

@@ -0,0 +1,30 @@
+CMake Warning at UnwindInclude/UnwindBlock.cmake:4 \(find_package\):
+  By not providing "Findfoo.cmake" in CMAKE_MODULE_PATH this project has
+  asked CMake to find a package configuration file provided by "foo", but
+  CMake did not find one.
+
+  Could not find a package configuration file provided by "foo" with any of
+  the following names:
+
+    fooConfig.cmake
+    foo-config.cmake
+
+  Add the installation prefix of "foo" to CMAKE_PREFIX_PATH or set "foo_DIR"
+  to a directory containing one of the above files.  If "foo" provides a
+  separate development package or SDK, be sure it has been installed.
+Call Stack \(most recent call first\):
+  UnwindInclude/PrimaryUnwindConfig.cmake:1 \(include\)
+  UnwindIncludeBlock.cmake:5 \(find_package\)
+  CMakeLists.txt:3 \(include\)
+
+
+CMake Warning at UnwindIncludeBlock.cmake:5 \(find_package\):
+  Found package configuration file:
+
+    [^
+]*/Tests/RunCMake/find_package/UnwindInclude/PrimaryUnwindConfig.cmake
+
+  but it set PrimaryUnwind_FOUND to FALSE so package "PrimaryUnwind" is
+  considered to be NOT FOUND.
+Call Stack \(most recent call first\):
+  CMakeLists.txt:3 \(include\)

Tests/RunCMake/find_package/UnwindIncludeBlock.cmake

@@ -0,0 +1,5 @@
+cmake_policy(SET CMP0074 NEW)
+set(PrimaryUnwind_ROOT ${CMAKE_CURRENT_SOURCE_DIR}/UnwindInclude)
+
+set(UNWIND_TARGET UnwindBlock)
+find_package(PrimaryUnwind)

Tests/RunCMake/find_package/UnwindIncludeFunction-stderr.txt

@@ -0,0 +1,31 @@
+CMake Warning at UnwindInclude/UnwindFunction.cmake:4 \(find_package\):
+  By not providing "Findfoo.cmake" in CMAKE_MODULE_PATH this project has
+  asked CMake to find a package configuration file provided by "foo", but
+  CMake did not find one.
+
+  Could not find a package configuration file provided by "foo" with any of
+  the following names:
+
+    fooConfig.cmake
+    foo-config.cmake
+
+  Add the installation prefix of "foo" to CMAKE_PREFIX_PATH or set "foo_DIR"
+  to a directory containing one of the above files.  If "foo" provides a
+  separate development package or SDK, be sure it has been installed.
+Call Stack \(most recent call first\):
+  UnwindInclude/UnwindFunction.cmake:15 \(f\)
+  UnwindInclude/PrimaryUnwindConfig.cmake:1 \(include\)
+  UnwindIncludeFunction.cmake:5 \(find_package\)
+  CMakeLists.txt:3 \(include\)
+
+
+CMake Warning at UnwindIncludeFunction.cmake:5 \(find_package\):
+  Found package configuration file:
+
+    [^
+]*/Tests/RunCMake/find_package/UnwindInclude/PrimaryUnwindConfig.cmake
+
+  but it set PrimaryUnwind_FOUND to FALSE so package "PrimaryUnwind" is
+  considered to be NOT FOUND.
+Call Stack \(most recent call first\):
+  CMakeLists.txt:3 \(include\)

Tests/RunCMake/find_package/UnwindIncludeFunction.cmake

@@ -0,0 +1,5 @@
+cmake_policy(SET CMP0074 NEW)
+set(PrimaryUnwind_ROOT ${CMAKE_CURRENT_SOURCE_DIR}/UnwindInclude)
+
+set(UNWIND_TARGET UnwindFunction)
+find_package(PrimaryUnwind)

Tests/RunCMake/find_package/UnwindIncludeInvalidContext-result.txt

@@ -0,0 +1 @@
+1

Tests/RunCMake/find_package/UnwindIncludeInvalidContext-stderr.txt

@@ -0,0 +1,4 @@
+CMake Error at UnwindIncludeInvalidContext.cmake:5 \(find_package\):
+  find_package called with UNWIND_INCLUDE in an invalid context
+Call Stack \(most recent call first\):
+  CMakeLists.txt:3 \(include\)

Tests/RunCMake/find_package/UnwindIncludeInvalidContext.cmake

@@ -0,0 +1,5 @@
+cmake_policy(SET CMP0074 NEW)
+set(PrimaryUnwind_ROOT ${CMAKE_CURRENT_SOURCE_DIR}/UnwindInclude)
+
+set(UNWIND_TARGET NoUnwind)
+find_package(PrimaryUnwind UNWIND_INCLUDE)

Tests/RunCMake/find_package/UnwindIncludeInvalidFindPackage-result.txt

@@ -0,0 +1 @@
+1

Tests/RunCMake/find_package/UnwindIncludeInvalidFindPackage-stderr.txt

@@ -0,0 +1,26 @@
+CMake Warning at UnwindInclude/UnwindInvalidFindPackage.cmake:1 \(find_package\):
+  By not providing "Findfoo.cmake" in CMAKE_MODULE_PATH this project has
+  asked CMake to find a package configuration file provided by "foo", but
+  CMake did not find one.
+
+  Could not find a package configuration file provided by "foo" with any of
+  the following names:
+
+    fooConfig.cmake
+    foo-config.cmake
+
+  Add the installation prefix of "foo" to CMAKE_PREFIX_PATH or set "foo_DIR"
+  to a directory containing one of the above files.  If "foo" provides a
+  separate development package or SDK, be sure it has been installed.
+Call Stack \(most recent call first\):
+  UnwindInclude/PrimaryUnwindConfig.cmake:1 \(include\)
+  UnwindIncludeInvalidFindPackage.cmake:5 \(find_package\)
+  CMakeLists.txt:3 \(include\)
+
+
+CMake Error at UnwindInclude/UnwindInvalidFindPackage.cmake:2 \(find_package\):
+  find_package called while already in an UNWIND state
+Call Stack \(most recent call first\):
+  UnwindInclude/PrimaryUnwindConfig.cmake:1 \(include\)
+  UnwindIncludeInvalidFindPackage.cmake:5 \(find_package\)
+  CMakeLists.txt:3 \(include\)

Tests/RunCMake/find_package/UnwindIncludeInvalidFindPackage.cmake

@@ -0,0 +1,5 @@
+cmake_policy(SET CMP0074 NEW)
+set(PrimaryUnwind_ROOT ${CMAKE_CURRENT_SOURCE_DIR}/UnwindInclude)
+
+set(UNWIND_TARGET UnwindInvalidFindPackage)
+find_package(PrimaryUnwind)

Tests/RunCMake/find_package/UnwindIncludeInvalidInclude-result.txt

@@ -0,0 +1 @@
+1

Tests/RunCMake/find_package/UnwindIncludeInvalidInclude-stderr.txt

@@ -0,0 +1,26 @@
+CMake Warning at UnwindInclude/UnwindInvalidInclude.cmake:1 \(find_package\):
+  By not providing "Findfoo.cmake" in CMAKE_MODULE_PATH this project has
+  asked CMake to find a package configuration file provided by "foo", but
+  CMake did not find one.
+
+  Could not find a package configuration file provided by "foo" with any of
+  the following names:
+
+    fooConfig.cmake
+    foo-config.cmake
+
+  Add the installation prefix of "foo" to CMAKE_PREFIX_PATH or set "foo_DIR"
+  to a directory containing one of the above files.  If "foo" provides a
+  separate development package or SDK, be sure it has been installed.
+Call Stack \(most recent call first\):
+  UnwindInclude/PrimaryUnwindConfig.cmake:1 \(include\)
+  UnwindIncludeInvalidInclude.cmake:5 \(find_package\)
+  CMakeLists.txt:3 \(include\)
+
+
+CMake Error at UnwindInclude/UnwindInvalidInclude.cmake:2 \(include\):
+  include called while already in an UNWIND state
+Call Stack \(most recent call first\):
+  UnwindInclude/PrimaryUnwindConfig.cmake:1 \(include\)
+  UnwindIncludeInvalidInclude.cmake:5 \(find_package\)
+  CMakeLists.txt:3 \(include\)

Tests/RunCMake/find_package/UnwindIncludeInvalidInclude.cmake

@@ -0,0 +1,5 @@
+cmake_policy(SET CMP0074 NEW)
+set(PrimaryUnwind_ROOT ${CMAKE_CURRENT_SOURCE_DIR}/UnwindInclude)
+
+set(UNWIND_TARGET UnwindInvalidInclude)
+find_package(PrimaryUnwind)

Tests/RunCMake/find_package/UnwindIncludeNoUnwind.cmake

@@ -0,0 +1,5 @@
+cmake_policy(SET CMP0074 NEW)
+set(PrimaryUnwind_ROOT ${CMAKE_CURRENT_SOURCE_DIR}/UnwindInclude)
+
+set(UNWIND_TARGET NoUnwind)
+find_package(PrimaryUnwind)

Tests/RunCMake/find_package/UnwindIncludeOnly-stderr.txt

@@ -0,0 +1,30 @@
+CMake Warning at UnwindInclude/UnwindOnly.cmake:1 \(find_package\):
+  By not providing "Findfoo.cmake" in CMAKE_MODULE_PATH this project has
+  asked CMake to find a package configuration file provided by "foo", but
+  CMake did not find one.
+
+  Could not find a package configuration file provided by "foo" with any of
+  the following names:
+
+    fooConfig.cmake
+    foo-config.cmake
+
+  Add the installation prefix of "foo" to CMAKE_PREFIX_PATH or set "foo_DIR"
+  to a directory containing one of the above files.  If "foo" provides a
+  separate development package or SDK, be sure it has been installed.
+Call Stack \(most recent call first\):
+  UnwindInclude/PrimaryUnwindConfig.cmake:1 \(include\)
+  UnwindIncludeOnly.cmake:5 \(find_package\)
+  CMakeLists.txt:3 \(include\)
+
+
+CMake Warning at UnwindIncludeOnly.cmake:5 \(find_package\):
+  Found package configuration file:
+
+    [^
+]*/Tests/RunCMake/find_package/UnwindInclude/PrimaryUnwindConfig.cmake
+
+  but it set PrimaryUnwind_FOUND to FALSE so package "PrimaryUnwind" is
+  considered to be NOT FOUND.
+Call Stack \(most recent call first\):
+  CMakeLists.txt:3 \(include\)

Tests/RunCMake/find_package/UnwindIncludeOnly.cmake

@@ -0,0 +1,5 @@
+cmake_policy(SET CMP0074 NEW)
+set(PrimaryUnwind_ROOT ${CMAKE_CURRENT_SOURCE_DIR}/UnwindInclude)
+
+set(UNWIND_TARGET UnwindOnly)
+find_package(PrimaryUnwind)

Tests/RunCMake/find_package/UnwindIncludeSecondary-stderr.txt

@@ -0,0 +1,24 @@
+CMake Warning at UnwindInclude/UnwindSecondary.cmake:1 \(find_package\):
+  Found package configuration file:
+
+    [^
+]*/Tests/RunCMake/find_package/UnwindInclude/SecondaryUnwindConfig.cmake
+
+  but it set SecondaryUnwind_FOUND to FALSE so package "SecondaryUnwind" is
+  considered to be NOT FOUND.
+Call Stack \(most recent call first\):
+  UnwindInclude/PrimaryUnwindConfig.cmake:1 \(include\)
+  UnwindIncludeSecondary.cmake:5 \(find_package\)
+  CMakeLists.txt:3 \(include\)
+
+
+CMake Warning at UnwindIncludeSecondary.cmake:5 \(find_package\):
+  Found package configuration file:
+
+    [^
+]*/Tests/RunCMake/find_package/UnwindInclude/PrimaryUnwindConfig.cmake
+
+  but it set PrimaryUnwind_FOUND to FALSE so package "PrimaryUnwind" is
+  considered to be NOT FOUND.
+Call Stack \(most recent call first\):
+  CMakeLists.txt:3 \(include\)

Tests/RunCMake/find_package/UnwindIncludeSecondary.cmake

@@ -0,0 +1,5 @@
+cmake_policy(SET CMP0074 NEW)
+set(PrimaryUnwind_ROOT ${CMAKE_CURRENT_SOURCE_DIR}/UnwindInclude)
+
+set(UNWIND_TARGET UnwindSecondary)
+find_package(PrimaryUnwind)