Use `thin` that starts with lowercase letter. - `Thin` gives an error when following https://clang.llvm.org/docs/ThinLTO.html#clang-bootstrap, and `thin` works.

[mingmingl]

Summary

Fix a typo.

[tejohnson]

There are some other docs that also use "Thin" (and "Full", etc). I see my own script uses "THIN" for this cmake variable. Looks like we convert to uppercase so I wouldn't think it should matter:
See llvm/cmake/modules/HandleLLVMOptions.cmake:30

Can you clarify what problem you are encountering? I'm not sure I understand the reference to WholeProgramDevirt.cpp in the title.

[mingmingl]

In D114764#3160204, @tejohnson wrote:

There are some other docs that also use "Thin" (and "Full", etc). I see my own script uses "THIN" for this cmake variable. Looks like we convert to uppercase so I wouldn't think it should matter:
See llvm/cmake/modules/HandleLLVMOptions.cmake:30

Can you clarify what problem you are encountering? I'm not sure I understand the reference to WholeProgramDevirt.cpp in the title.

Thanks for pointing this out! The title should be https://clang.llvm.org/docs/ThinLTO.html#clang-bootstrap (WholeProgramDevirt should be from stale paste board).

I made a mistake in the command; re-run the command works for me [1]; previously I remember seeing flto 'Thin' in the terminal, so must have mixed the clang cmmand and cmake command.

Going to revert this.

[1] cmake -G Ninja -DCMAKE_BUILD_TYPE=Debug -DLLVM_ENABLE_SPHINX=true -DLLVM_USE_LINKER=lld -DLLVM_CCACHE_BUILD=On -DSPHINX_OUTPUT_HTML=true -DLLVM_ENABLE_PROJECTS='clang;compiler-rt;lld' /path/to/llvm-project/llvm -DLLVM_BINUTILS_INCDIR=/path/to/binutils/include -DLLVM_ENABLE_LTO=Thin -DLLVM_PARALLEL_LINK_JOBS=1 -DCMAKE_C_COMPILER=/usr/local/bin/clang -DCMAKE_CXX_COMPILER=/usr/local/bin/clang++ -DCMAKE_RANLIB=/usr/local/bin/llvm-ranlib -DCMAKE_AR=/usr/local/bin/llvm-ar

[tejohnson]

In D114764#3160212, @luna wrote:

In D114764#3160204, @tejohnson wrote:

There are some other docs that also use "Thin" (and "Full", etc). I see my own script uses "THIN" for this cmake variable. Looks like we convert to uppercase so I wouldn't think it should matter:
See llvm/cmake/modules/HandleLLVMOptions.cmake:30

Can you clarify what problem you are encountering? I'm not sure I understand the reference to WholeProgramDevirt.cpp in the title.

Thanks for pointing this out! The title should be https://clang.llvm.org/docs/ThinLTO.html#clang-bootstrap (WholeProgramDevirt should be from stale paste board).

I made a mistake in the command; re-run the command works for me [1]; previously I remember seeing flto 'Thin' in the terminal, so must have mixed the clang cmmand and cmake command.

Ah ok, glad that works now. Yes, it is case sensitive lowercase for the clang option, but not for the cmake variable.

Going to revert this.

[1] cmake -G Ninja -DCMAKE_BUILD_TYPE=Debug -DLLVM_ENABLE_SPHINX=true -DLLVM_USE_LINKER=lld -DLLVM_CCACHE_BUILD=On -DSPHINX_OUTPUT_HTML=true -DLLVM_ENABLE_PROJECTS='clang;compiler-rt;lld' /path/to/llvm-project/llvm -DLLVM_BINUTILS_INCDIR=/path/to/binutils/include -DLLVM_ENABLE_LTO=Thin -DLLVM_PARALLEL_LINK_JOBS=1 -DCMAKE_C_COMPILER=/usr/local/bin/clang -DCMAKE_CXX_COMPILER=/usr/local/bin/clang++ -DCMAKE_RANLIB=/usr/local/bin/llvm-ranlib -DCMAKE_AR=/usr/local/bin/llvm-ar

clang/docs/ThinLTO.rst

 
 1. The host compiler_ must be a version of clang that supports ThinLTO.
 #. The host linker_ must support ThinLTO (and in the case of gold, must be
    `configured with plugins enabled <https://llvm.org/docs/GoldPlugin.html>`_).
 #. Use the following additional `CMake variables
    <https://llvm.org/docs/CMake.html#options-and-variables>`_
    when configuring the bootstrap compiler build:
 
-  * ``-DLLVM_ENABLE_LTO=Thin``
+  * ``-DLLVM_ENABLE_LTO=thin``
   * ``-DCMAKE_C_COMPILER=/path/to/host/clang``
   * ``-DCMAKE_CXX_COMPILER=/path/to/host/clang++``
   * ``-DCMAKE_RANLIB=/path/to/host/llvm-ranlib``
   * ``-DCMAKE_AR=/path/to/host/llvm-ar``
 
   Or, on Windows:
 
-  * ``-DLLVM_ENABLE_LTO=Thin``
+  * ``-DLLVM_ENABLE_LTO=thin``
   * ``-DCMAKE_C_COMPILER=/path/to/host/clang-cl.exe``
   * ``-DCMAKE_CXX_COMPILER=/path/to/host/clang-cl.exe``
   * ``-DCMAKE_LINKER=/path/to/host/lld-link.exe``
   * ``-DCMAKE_RANLIB=/path/to/host/llvm-ranlib.exe``
   * ``-DCMAKE_AR=/path/to/host/llvm-ar.exe``
 
 #. To use additional linker arguments for controlling the backend
    parallelism_ or enabling incremental_ builds of the bootstrap compiler,