[MLIR][Python] fix stubgen (#157583)

In https://github.com/llvm/llvm-project/pull/155741 I broke the cardinal
rule of CMake: nothing happens when you think it happens 🤷. Meaning:
`declare_mlir_python_sources(SOURCES_GLOB
"_mlir_libs/${_module_name}/**/*.pyi")` wasn't picking up any sources
_because they aren't generated yet_. This of course makes sense in
retrospect (the stubs are generated as part of the build process, post
extension compile, rather than the configure process).

Thus, the API needs to be:

```
GENERATE_TYPE_STUBS: List of generated type stubs expected from stubgen, relative to _mlir_libs.
```

Partially as a result of this omission, the stubs weren't being
installed into either the build dir nor the install dir. That is also
fixed now:

**Source dir (for easy reference):**

<img width="300" height="674" alt="image"
src="https://github.com/user-attachments/assets/a569f066-c2bd-4361-91f3-1c75181e51da"
/>

**Build dir (for forthcoming typechecker tests):**

<img width="398" height="551" alt="image"
src="https://github.com/user-attachments/assets/017859f9-fddb-49ee-85e5-915f5b5f7377"
/>

**Install dir:**

<img width="456" height="884" alt="image"
src="https://github.com/user-attachments/assets/8051be7e-898c-4ec8-a11e-e2408b241a56"
/>

mlir/python/CMakeLists.txt

@@ -506,6 +506,10 @@ declare_mlir_python_extension(MLIRPythonExtension.Core
     # Dialects
     MLIRCAPIFunc
   GENERATE_TYPE_STUBS
+    "_mlir/__init__.pyi"
+    "_mlir/ir.pyi"
+    "_mlir/passmanager.pyi"
+    "_mlir/rewrite.pyi"
 )
 
 # This extension exposes an API to register all dialects, extensions, and passes
@@ -528,6 +532,7 @@ declare_mlir_python_extension(MLIRPythonExtension.RegisterEverything
     MLIRCAPITransforms
     MLIRCAPIRegisterEverything
   GENERATE_TYPE_STUBS
+    "_mlirRegisterEverything.pyi"
 )
 
 declare_mlir_python_extension(MLIRPythonExtension.Dialects.Linalg.Pybind
@@ -543,6 +548,7 @@ declare_mlir_python_extension(MLIRPythonExtension.Dialects.Linalg.Pybind
     MLIRCAPIIR
     MLIRCAPILinalg
   GENERATE_TYPE_STUBS
+    "_mlirDialectsLinalg.pyi"
 )
 
 declare_mlir_python_extension(MLIRPythonExtension.Dialects.GPU.Pybind
@@ -558,6 +564,7 @@ declare_mlir_python_extension(MLIRPythonExtension.Dialects.GPU.Pybind
     MLIRCAPIIR
     MLIRCAPIGPU
   GENERATE_TYPE_STUBS
+    "_mlirDialectsGPU.pyi"
 )
 
 declare_mlir_python_extension(MLIRPythonExtension.Dialects.LLVM.Pybind
@@ -573,6 +580,7 @@ declare_mlir_python_extension(MLIRPythonExtension.Dialects.LLVM.Pybind
     MLIRCAPIIR
     MLIRCAPILLVM
   GENERATE_TYPE_STUBS
+    "_mlirDialectsLLVM.pyi"
 )
 
 declare_mlir_python_extension(MLIRPythonExtension.Dialects.Quant.Pybind
@@ -588,6 +596,7 @@ declare_mlir_python_extension(MLIRPythonExtension.Dialects.Quant.Pybind
     MLIRCAPIIR
     MLIRCAPIQuant
   GENERATE_TYPE_STUBS
+    "_mlirDialectsQuant.pyi"
 )
 
 declare_mlir_python_extension(MLIRPythonExtension.Dialects.NVGPU.Pybind
@@ -603,6 +612,7 @@ declare_mlir_python_extension(MLIRPythonExtension.Dialects.NVGPU.Pybind
     MLIRCAPIIR
     MLIRCAPINVGPU
   GENERATE_TYPE_STUBS
+    "_mlirDialectsNVGPU.pyi"
 )
 
 declare_mlir_python_extension(MLIRPythonExtension.Dialects.PDL.Pybind
@@ -618,6 +628,7 @@ declare_mlir_python_extension(MLIRPythonExtension.Dialects.PDL.Pybind
     MLIRCAPIIR
     MLIRCAPIPDL
   GENERATE_TYPE_STUBS
+    "_mlirDialectsPDL.pyi"
 )
 
 declare_mlir_python_extension(MLIRPythonExtension.Dialects.SparseTensor.Pybind
@@ -633,6 +644,7 @@ declare_mlir_python_extension(MLIRPythonExtension.Dialects.SparseTensor.Pybind
     MLIRCAPIIR
     MLIRCAPISparseTensor
   GENERATE_TYPE_STUBS
+    "_mlirDialectsSparseTensor.pyi"
 )
 
 declare_mlir_python_extension(MLIRPythonExtension.Dialects.Transform.Pybind
@@ -648,6 +660,7 @@ declare_mlir_python_extension(MLIRPythonExtension.Dialects.Transform.Pybind
     MLIRCAPIIR
     MLIRCAPITransformDialect
   GENERATE_TYPE_STUBS
+    "_mlirDialectsTransform.pyi"
 )
 
 declare_mlir_python_extension(MLIRPythonExtension.AsyncDialectPasses
@@ -662,6 +675,7 @@ declare_mlir_python_extension(MLIRPythonExtension.AsyncDialectPasses
   EMBED_CAPI_LINK_LIBS
     MLIRCAPIAsync
   GENERATE_TYPE_STUBS
+    "_mlirAsyncPasses.pyi"
 )
 
 if(MLIR_ENABLE_EXECUTION_ENGINE)
@@ -677,6 +691,7 @@ if(MLIR_ENABLE_EXECUTION_ENGINE)
     EMBED_CAPI_LINK_LIBS
       MLIRCAPIExecutionEngine
     GENERATE_TYPE_STUBS
+      "_mlirExecutionEngine.pyi"
   )
 endif()
 
@@ -692,6 +707,7 @@ declare_mlir_python_extension(MLIRPythonExtension.GPUDialectPasses
   EMBED_CAPI_LINK_LIBS
     MLIRCAPIGPU
   GENERATE_TYPE_STUBS
+    "_mlirGPUPasses.pyi"
 )
 
 declare_mlir_python_extension(MLIRPythonExtension.LinalgPasses
@@ -706,6 +722,7 @@ declare_mlir_python_extension(MLIRPythonExtension.LinalgPasses
   EMBED_CAPI_LINK_LIBS
     MLIRCAPILinalg
   GENERATE_TYPE_STUBS
+    "_mlirLinalgPasses.pyi"
 )
 
 declare_mlir_python_extension(MLIRPythonExtension.Dialects.SMT.Pybind
@@ -724,6 +741,7 @@ declare_mlir_python_extension(MLIRPythonExtension.Dialects.SMT.Pybind
     MLIRCAPISMT
     MLIRCAPIExportSMTLIB
   GENERATE_TYPE_STUBS
+    "_mlirDialectsSMT.pyi"
 )
 
 declare_mlir_python_extension(MLIRPythonExtension.SparseTensorDialectPasses
@@ -738,6 +756,7 @@ declare_mlir_python_extension(MLIRPythonExtension.SparseTensorDialectPasses
   EMBED_CAPI_LINK_LIBS
     MLIRCAPISparseTensor
   GENERATE_TYPE_STUBS
+    "_mlirSparseTensorPasses.pyi"
 )
 
 declare_mlir_python_extension(MLIRPythonExtension.TransformInterpreter
@@ -752,6 +771,7 @@ declare_mlir_python_extension(MLIRPythonExtension.TransformInterpreter
   EMBED_CAPI_LINK_LIBS
     MLIRCAPITransformDialectTransforms
   GENERATE_TYPE_STUBS
+    "_mlirTransformInterpreter.pyi"
 )
 
 # TODO: Figure out how to put this in the test tree.
@@ -811,6 +831,7 @@ if(MLIR_INCLUDE_TESTS)
     EMBED_CAPI_LINK_LIBS
       MLIRCAPIPythonTestDialect
     GENERATE_TYPE_STUBS
+      "_mlirPythonTestNanobind.pyi"
   )
 endif()
 

mlir/python/mlir/_mlir_libs/.gitignore

@@ -1 +1,2 @@
 _mlir/**/*.pyi
+*.pyi