[llvm-dev] [CMake] Re-configuring Debug and Release builds

[Shoaib Meenai via llvm-dev]

I'm unable to repro this – configuring once and then reconfiguring with a different -DCMAKE_BUILD_TYPE= does the right thing for me. What's your exact invocation?

If you're setting it from a cache file, you'll need to use FORCE in the set in your cache file to override any existing cache setting.

On 3/8/19, 1:18 PM, "llvm-dev on behalf of David Greene via llvm-dev" <llvm-dev-bounces at lists.llvm.org on behalf of llvm-dev at lists.llvm.org> wrote:

    <paul.robinson at sony.com> writes:
    
    >> If I've configured a Release build, build it and then go back and re-run
    >> cmake with -DCMAKE_BUILD_TYPE=Debug (and nothing else changed), almost
    >> nothing gets rebuilt when I try to build.  Is this expected?  I know I
    >> can edit CMakeCache.txt directly and trigger an essentially full
    >> rebuild.
    >
    > IME rerunning CMake with new options really does nothing; CMakeCache.txt
    > appears to override the command line, which is not intuitive but seems
    > to be how it actually works.
    
    I thought so too at first, except changing LLVM_TARGETS_TO_BUILD when
    re-running CMake does indeed cause any new targets to be built.  So it
    can't be the case that the cache overrides everything.
    
    > I would hope that this is not a choice made by the LLVM project but a
    > bug/feature of CMake itself.  But I haven't ever had the energy to 
    > pursue it.
    
    https://urldefense.proofpoint.com/v2/url?u=https-3A__llvm.org_docs_CMake.html-23cmake-2Dcaches&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=QX_nCpK2peaty_XOC8I0mM2FCcsrB0u93ckBWasLzfU&s=krJ8pnxDwobl6hQ3IB_hpM54u0pvD5MU-Ft5l6EL__4&e= seems to imply that -D
    options should override cache values, but it doesn't for
    CMAKE_BUILD_TYPE.
    
                                   -David
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