Define Python_FIND_VIRTUALENV in addition to Python3_FIND_VIRTUALENV

MLIR searches for both Python3 and Python. If both variables are not
defined equally and there multiple python version on the system, CMake
may behave really weirdly.

More details here: llvm/llvm-project#126162

Author: dbabokin

build_tools/e2eshark_build.sh

@@ -21,6 +21,7 @@ cmake -S "$repo_root/externals/llvm-project/llvm" -B "$build_dir" \
   -GNinja \
   -DCMAKE_BUILD_TYPE=Release \
   -DPython3_FIND_VIRTUALENV=ONLY \
+  -DPython_FIND_VIRTUALENV=ONLY \
   -DLLVM_ENABLE_PROJECTS=mlir \
   -DLLVM_EXTERNAL_PROJECTS="torch-mlir" \
   -DLLVM_EXTERNAL_TORCH_MLIR_SOURCE_DIR="$PWD" \

build_tools/python_deploy/build_windows_ci.sh

@@ -33,6 +33,7 @@ cmake -GNinja -Bbuild \
   -DLLVM_TARGETS_TO_BUILD=host \
   -DMLIR_ENABLE_BINDINGS_PYTHON=ON \
   -DPython3_FIND_VIRTUALENV=ONLY \
+  -DPython_FIND_VIRTUALENV=ONLY \
   -DLLVM_EXTERNAL_PROJECTS="torch-mlir" \
   -DLLVM_EXTERNAL_TORCH_MLIR_SOURCE_DIR="$PWD" \
   -DPython3_EXECUTABLE="$(which python)" \

docs/development.md

@@ -105,6 +105,7 @@ sudo apt install clang ccache lld
           -DCMAKE_BUILD_TYPE=RelWithDebInfo \
           -DLLVM_ENABLE_ASSERTIONS=ON \
           -DPython3_FIND_VIRTUALENV=ONLY \
+          -DPython_FIND_VIRTUALENV=ONLY \
           -DMLIR_ENABLE_BINDINGS_PYTHON=ON \
           -DLLVM_TARGETS_TO_BUILD=host \
           `# For building LLVM "in-tree"` \
@@ -123,6 +124,7 @@ sudo apt install clang ccache lld
           -DCMAKE_BUILD_TYPE=RelWithDebInfo \
           -DLLVM_ENABLE_ASSERTIONS=ON \
           -DPython3_FIND_VIRTUALENV=ONLY \
+          -DPython_FIND_VIRTUALENV=ONLY \
           -DMLIR_ENABLE_BINDINGS_PYTHON=ON \
           -DLLVM_TARGETS_TO_BUILD=host \
           `# For building LLVM "out-of-tree"` \

setup.py

@@ -113,6 +113,8 @@ def cmake_build(self, cmake_build_dir):
             f"-DCMAKE_BUILD_TYPE={CMAKE_BUILD_TYPE}",
             f"-DPython3_EXECUTABLE={sys.executable}",
             f"-DPython3_FIND_VIRTUALENV=ONLY",
+            f"-DPython_EXECUTABLE={sys.executable}",
+            f"-DPython_FIND_VIRTUALENV=ONLY",
             f"-DMLIR_ENABLE_BINDINGS_PYTHON=ON",
             f"-DLLVM_TARGETS_TO_BUILD=host",
             f"-DLLVM_ENABLE_ZSTD=OFF",