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0013171

CMake

public

2012-04-26 14:15

2012-09-03 16:02

Reporter

bungeman

Assigned To

Brad King

Priority

normal

Severity

minor

Reproducibility

always

Status

closed

Resolution

not fixable

Platform

Linux

Ubuntu

OS Version

12.04

Product Version

CMake 2.8.8

Target Version

Fixed in Version

Summary

0013171: Default target LINKER_LANGUAGE un-gettable.

Description

This was first reported on the mailing list here

http://www.cmake.org/pipermail/cmake/2009-May/029570.html [^]

but apparently it never made it to the bug tracker as was suggested in the reply. However, I recently ran into this issue. The basic problem is that the defaults of many properties cannot be retrieved. CMake obviously knows what the values are, but will not expose them.

Steps To Reproduce

Put something like the following into a CMakeLists.txt

add_executable(target
target.c
)
get_target_property(TARGET_LINKER_LANGUAGE target LINKER_LANGUAGE)
message("TARGET_LINKER_LANGUAGE = ${TARGET_LINKER_LANGUAGE}")
if(${TARGET_LINKER_LANGUAGE} EQUAL "CXX")
set_property(TARGET target APPEND PROPERTIES COMPILE_FLAGS "-fno-rtti -fno-threadsafe-statics -fvisibility-inlines-hidden -Wno-deprecated ")
endif()
unset(TARGET_LINKER_LANGUAGE)

The output looks like

TARGET_LINKER_LANGUAGE = TARGET_LINKER_LANGUAGE-NOTFOUND

and of course the 'if' will never evaluate to true.

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Notes
(0029350) Brad King (manager) 2012-04-26 14:21	The properties do not document that they can be retrieved. They document that the project can SET them explicitly. Most of the time the default is NOT known while the CMakeLists.txt files are being processed. The value is not computed until the generate step. In this case especially there is not sufficient information available until the generate step to compute the final default value. Your project will have to keep track by itself whether it adds C++ sources or not. Alternatively it can just put the flags in CMAKE_CXX_FLAGS and they will be used for compiling C++ sources but not C. Ask for more detail on the mailing list if you need further help.

(0030897) David Cole (manager) 2012-09-03 16:02	Closing resolved issues that have not been updated in more than 4 months.

Issue History
Date Modified	Username	Field	Change
2012-04-26 14:15	bungeman	New Issue
2012-04-26 14:21	Brad King	Note Added: 0029350
2012-04-26 14:21	Brad King	Status	new => resolved
2012-04-26 14:21	Brad King	Resolution	open => not fixable
2012-04-26 14:21	Brad King	Assigned To	=> Brad King
2012-09-03 16:02	David Cole	Note Added: 0030897
2012-09-03 16:02	David Cole	Status	resolved => closed