MantisBT - CMake
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ID	Project	Category	View Status	Date Submitted	Last Update
0008192	CMake	CMake	public	2008-11-28 11:06	2009-02-24 15:15

Reporter	Thorsten Köster
Assigned To	Brad King
Priority	normal	Severity	feature	Reproducibility	always
Status	closed	Resolution	fixed
Platform		OS		OS Version
Product Version	CMake-2-6
Target Version		Fixed in Version

Summary	0008192: Included scripts should be protected by policy push/pop
Description	Linking to libraries with hard-coded paths and non-standard extensions leads to what seems to be the "OLD" behaviour in CMake-2.6.2, i.e. the paths are removed and the standard extension is added.
Steps To Reproduce
Additional Information	CMAKE_POLICY(GET CMP0008 somevar) results in an empty somevar. Original summary: Policy CMP0008 is not honoured in CMake-2.6.2 Summary was changed after true problem was discovered.
Tags	No tags attached.
Relationships
Attached Files	CMakeLists.txt (133) 2008-12-01 03:24 https://public.kitware.com/Bug/file/1879/CMakeLists.txt IncludeFile.cmake (37) 2008-12-01 03:24 https://public.kitware.com/Bug/file/1880/IncludeFile.cmake

Issue History
Date Modified	Username	Field	Change
2008-11-28 11:06	Thorsten Köster	New Issue
2008-11-28 11:29	Bill Hoffman	Note Added: 0014225
2008-11-28 11:29	Bill Hoffman	Status	new => assigned
2008-11-28 11:29	Bill Hoffman	Assigned To	=> Brad King
2008-12-01 03:24	Thorsten Köster	File Added: CMakeLists.txt
2008-12-01 03:24	Thorsten Köster	File Added: IncludeFile.cmake
2008-12-01 03:32	Thorsten Köster	Note Added: 0014259
2008-12-15 15:54	Brad King	Note Added: 0014353
2008-12-15 15:54	Brad King	Status	assigned => closed
2008-12-15 15:54	Brad King	Resolution	open => no change required
2009-01-15 16:37	Brad King	Note Added: 0014578
2009-01-15 16:37	Brad King	Status	closed => feedback
2009-01-15 16:37	Brad King	Resolution	no change required => reopened
2009-01-15 16:39	Brad King	Severity	major => feature
2009-01-15 16:39	Brad King	Status	feedback => assigned
2009-01-15 16:39	Brad King	Summary	Policy CMP0008 is not honoured in CMake-2.6.2 => Included scripts should be protected by policy push/pop
2009-01-15 16:39	Brad King	Additional Information Updated
2009-01-22 13:40	Brad King	Note Added: 0014662
2009-01-22 13:44	Brad King	Note Added: 0014663
2009-01-22 13:45	Brad King	Note Edited: 0014662
2009-02-24 15:15	Brad King	Note Added: 0015338
2009-02-24 15:15	Brad King	Status	assigned => closed
2009-02-24 15:15	Brad King	Resolution	reopened => fixed

Notes

There are two types of included files:

(1) Those included from inside the project's source tree
(2) Those included from an outside third-party project installation

Files of type (1) usually don't change policies and just use the policies of the main project. For these it doesn't matter whether policies are protected by a push/pop or not. It is possible that the purpose of a file is to set policies for its including context, but that is a special case.

Files of type (2) should use cmake_minimum_required to enforce a version. Usually the including project just wants the file to do what it documents and doesn't care that it may have been written for a different version of CMake. For these files the including project should be protected by a push/pop.

There is also a special case utilized by KDE4 in which application authors can write

  # No cmake_minimum_required!!
  project(mykde4app)
  find_package(KDE4) # Has cmake_minimum_required and sets some policies

The file included by the find_package command sets CMP0000 to OLD to quiet the warning that the top file should have cmake_minimum_required. Any change we make needs to preserve this "development framework" use case.

We've concluded that in the common case include() and find_package() should protect their calling contexts from the included file by automatically implying a cmake_policy(PUSH) and cmake_policy(POP) around the loaded files. I've committed changes that make the commands do this by default but provide a NO_POLICY_SCOPE option to disable it. I've introduced policy CMP0011 for compatibility. It's OLD behavior is to imply NO_POLICY_SCOPE and its NEW behavior is to not imply the option. This supports the KDE4 use case because the find_package(KDE4) line occurs before CMP0011 has been set, so it uses the OLD behavior (and if the included file sets CMP0011 then there is no warning).

The changes also make functions and macros record policies set when they are created and use them when they are invoked. This is important so that functions provided by a third-party script run with the policies they expect.

The following series of commits implement the new bheavior.

Author: Brad King <brad.king@kitware.com>
Date: Thu Jan 22 15:56:39 2009 +0000

    ENH: Refactor policy stack representation

    This defines PolicyMap as a public member of cmPolicies. Its previous
    role as a policy stack entry is now called PolicyStackEntry and
    represented as a class to which more information can be added later.

Source/cmMakefile.cxx | 7 +++----
Source/cmMakefile.h | 12 +++++++++---
Source/cmPolicies.h | 4 ++++
3 files changed, 16 insertions(+), 7 deletions(-)

Author: Brad King <brad.king@kitware.com>
Date: Thu Jan 22 15:56:50 2009 +0000

    ENH: Create automatic policy push/pop helper

    This creates cmMakefile::PolicyPushPop to push and pop policy scope
    automatically. It also enforces balanced push/pop pairs inside the
    scope it handles.

Source/cmMakefile.cxx | 29 +++++++++++++++++++++++++++++
Source/cmMakefile.h | 12 ++++++++++++
2 files changed, 41 insertions(+), 0 deletions(-)

Author: Brad King <brad.king@kitware.com>
Date: Thu Jan 22 15:56:58 2009 +0000

    ENH: Refactor find_package version file scoping

    This converts the variable and policy scope protection find_package()
    uses when loading version files to use automatic variables.

Source/cmFindPackageCommand.cxx | 10 ++++------
1 files changed, 4 insertions(+), 6 deletions(-)

Author: Brad King <brad.king@kitware.com>
Date: Thu Jan 22 15:57:09 2009 +0000

    ENH: Make policy push/pop methods private

    This makes cmMakefile::PushPolicy and cmMakefile::PopPolicy private so
    that any outside place that uses them needs to use the PolicyPushPop
    helper in an automatic variable. We grant an exception to
    cmCMakePolicyCommand so it can implement cmake_policy(PUSH) and
    cmake_policy(POP).

Source/cmMakefile.h | 10 +++++++---
1 files changed, 7 insertions(+), 3 deletions(-)

Author: Brad King <brad.king@kitware.com>
Date: Thu Jan 22 15:57:16 2009 +0000

    ENH: Create policy scope barriers

    This creates a barrier mechanism to prevent user code from using
    cmake_policy(POP) to pop a scope it didn't push with cmake_policy(PUSH).

Source/cmCMakePolicyCommand.cxx | 14 ++----
Source/cmMakefile.cxx | 110 ++++++++++++++++++++++++--------------
Source/cmMakefile.h | 12 +++-
3 files changed, 82 insertions(+), 54 deletions(-)

Author: Brad King <brad.king@kitware.com>
Date: Thu Jan 22 18:16:27 2009 +0000

    ENH: Create notion of a 'weak' policy stack entry

    A 'weak' poilcy stack entry responds normally to queries. However,
    setting a policy in a weak entry will recursively set the policy in the
    next entry too. This also gives the internal interface to create a weak
    entry the option to provide an initial PolicyMap for it.

Source/cmMakefile.cxx | 19 +++++++++++++------
Source/cmMakefile.h | 14 +++++++++-----
2 files changed, 22 insertions(+), 11 deletions(-)

Author: Brad King <brad.king@kitware.com>
Date: Thu Jan 22 18:16:33 2009 +0000

    ENH: Improve stack discussion in cmake_policy

    This re-organizes the discussion of the policy stack in documentation of
    the cmake_policy() command. The new organization clearer and easier to
    extend with new information.

Source/cmCMakePolicyCommand.h | 17 +++++++++--------
1 files changed, 9 insertions(+), 8 deletions(-)

Author: Brad King <brad.king@kitware.com>
Date: Thu Jan 22 18:16:47 2009 +0000

    ENH: Better policies for functions and macros

    This teaches functions and macros to use policies recorded at creation
    time when they are invoked. It restores the policies as a weak policy
    stack entry so that any policies set by a function escape to its caller
    as before.

Source/cmCMakePolicyCommand.h | 6 ++++
Source/cmFunctionCommand.cxx | 8 +++++
Source/cmFunctionCommand.h | 6 +++-
Source/cmMacroCommand.cxx | 8 +++++
Source/cmMacroCommand.h | 6 +++-
Source/cmMakefile.cxx | 12 ++++++++
Source/cmMakefile.h | 1 +
Tests/CMakeLists.txt | 1 +
Tests/PolicyScope/CMakeLists.txt | 55 ++++++++++++++++++++++++++++++++++++++
Tests/PolicyScope/main.c | 4 +++
10 files changed, 105 insertions(+), 2 deletions(-)

Author: Brad King <brad.king@kitware.com>
Date: Thu Jan 22 18:18:40 2009 +0000

    ENH: Isolate policy changes in included scripts

    Isolation of policy changes inside scripts is important for protecting
    the including context. This teaches include() and find_package() to
    imply a cmake_policy(PUSH) and cmake_policy(POP) around the scripts they
    load, with a NO_POLICY_SCOPE option to disable the behavior. This also
    creates CMake Policy CMP0011 to provide compatibility. See issue 0008192.

Source/cmCMakePolicyCommand.h | 3 +
Source/cmFindPackageCommand.cxx | 30 ++++++++---
Source/cmFindPackageCommand.h | 4 +-
Source/cmIncludeCommand.cxx | 8 +++-
Source/cmIncludeCommand.h | 10 +++-
Source/cmMakefile.cxx | 107 ++++++++++++++++++++++++++++++++++++--
Source/cmMakefile.h | 3 +-
Source/cmPolicies.cxx | 20 +++++++
Source/cmPolicies.h | 1 +
Tests/PolicyScope/Bar.cmake | 8 +++
Tests/PolicyScope/CMakeLists.txt | 33 +++++++++++-
Tests/PolicyScope/FindFoo.cmake | 2 +
12 files changed, 210 insertions(+), 19 deletions(-)