711b63f7e0
Historically CMake has always expanded ${} variable references in the
values given to include_directories(), link_directories(), and
link_libraries(). This has been unnecessary since general ${}
evaluation syntax was added to the language a LONG time ago, but has
remained for compatibility with VERY early CMake versions.
For a long time the re-expansion was a lightweight operation because it
was only processed once at the directory level and the fast-path of
cmMakefile::ExpandVariablesInString was usually taken because values did
not have any '$' in them. Then commit d899eb71 (Call
ExpandVariablesInString for each target's INCLUDE_DIRECTORIES,
2012-02-22) made the operation a bit heavier because the expansion is
now needed on a per-target basis. In the future we will support
generator expressions in INCLUDE_DIRECTORIES with $<> syntax, so the
fast-path in cmMakefile::ExpandVariablesInString will no longer be taken
and re-expansion will be very expensive.
Add policy CMP0019 to skip the re-expansion altogether in NEW behavior.
In OLD behavior perform the expansion but improve the fast-path
heuristic to match ${} but not $<>. If the policy is not set then warn
if expansion actually does anything. We expect this to be encountered
very rarely in practice.
41 lines
875 B
Plaintext
41 lines
875 B
Plaintext
CMake Warning \(dev\) in CMakeLists.txt:
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Policy CMP0019 is not set: Do not re-expand variables in include and link
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information. Run "cmake --help-policy CMP0019" for policy details. Use
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the cmake_policy command to set the policy and suppress this warning.
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The following variable evaluations were encountered:
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Evaluated directory INCLUDE_DIRECTORIES
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/usr/include/\${VAR_INCLUDE};/usr/include/normal
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as
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/usr/include/VAL_INCLUDE;/usr/include/normal
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Evaluated target some_target INCLUDE_DIRECTORIES
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/usr/include/\${VAR_INCLUDE};/usr/include/normal
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as
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/usr/include/VAL_INCLUDE;/usr/include/normal
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Evaluated link directory
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/usr/lib/\${VAR_LINK_DIRS}
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as
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/usr/lib/VAL_LINK_DIRS
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Evaluated link library
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\${VAR_LINK_LIBS}
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as
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VAL_LINK_LIBS
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This warning is for project developers. Use -Wno-dev to suppress it.$
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