LLDBStandalone: Report nice errors on missing vars

[chaoren]

Seems legit. But I've never built standalone, so I probably shouldn't be a reviewer for this.

[clayborg]

I don't build cmake either, I am probably not a great person to ask. Todd Fiala might be a good person.

[brucem]

This looks reasonable to me as well, but I also have never built standalone.

[tfiala]

I'll have a look. How do I test it, @artagnon?

[artagnon]

Okay, so run this on the current HEAD:

$ cmake -GNinja -DCMAKE_BUILD_TYPE=Debug ../lldb
-- The C compiler identification is AppleClang 6.1.0.6020053
-- The CXX compiler identification is AppleClang 6.1.0.6020053
-- Check for working C compiler using: Ninja
-- Check for working C compiler using: Ninja -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler using: Ninja
-- Check for working CXX compiler using: Ninja -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
CMake Error at cmake/modules/LLDBStandalone.cmake:37 (get_filename_component):
  get_filename_component called with incorrect number of arguments
Call Stack (most recent call first):
  CMakeLists.txt:3 (include)


CMake Error at cmake/modules/LLDBStandalone.cmake:40 (get_filename_component):
  get_filename_component called with incorrect number of arguments
Call Stack (most recent call first):
  CMakeLists.txt:3 (include)


CMake Error at cmake/modules/LLDBStandalone.cmake:48 (include):
  include could not find load file:

    AddLLVM
Call Stack (most recent call first):
  CMakeLists.txt:3 (include)


CMake Error at cmake/modules/LLDBStandalone.cmake:49 (include):
  include could not find load file:

    HandleLLVMOptions
Call Stack (most recent call first):
  CMakeLists.txt:3 (include)


-- Found PythonInterp:
CMake Error at cmake/modules/LLDBStandalone.cmake:63 (include):
  include could not find load file:

    /share/llvm/cmake/LLVMConfig.cmake
Call Stack (most recent call first):
  CMakeLists.txt:3 (include)


-- Found PythonLibs: /usr/lib/libpython2.7.dylib (found version "2.7.10")
CMake Error at cmake/modules/LLDBConfig.cmake:205 (check_cxx_compiler_flag):
  Unknown CMake command "check_cxx_compiler_flag".
Call Stack (most recent call first):
  CMakeLists.txt:4 (include)


-- Configuring incomplete, errors occurred!
See also "/home/rramacha/src/lldb-build2/CMakeFiles/CMakeOutput.log".

Cryptic syntax errors right? Now apply the patch and run:

$ cmake -GNinja -DCMAKE_BUILD_TYPE=Debug ../lldb
-- The C compiler identification is AppleClang 6.1.0.6020053
-- The CXX compiler identification is AppleClang 6.1.0.6020053
-- Check for working C compiler using: Ninja
-- Check for working C compiler using: Ninja -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler using: Ninja
-- Check for working CXX compiler using: Ninja -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
CMake Error at cmake/modules/LLDBStandalone.cmake:43 (message):
  Please set LLDB_PATH_TO_LLVM_BUILD to the root directory of LLVM build or
  install site.
Call Stack (most recent call first):
  CMakeLists.txt:3 (include)


-- Configuring incomplete, errors occurred!
See also "/home/rramacha/src/lldb-build2/CMakeFiles/CMakeOutput.log".

Great. To fix that, run:

$ cmake -GNinja -DCMAKE_BUILD_TYPE=Debug -DLLDB_PATH_TO_LLVM_BUILD=~/src/llvm-build ../lldb
-- The C compiler identification is AppleClang 6.1.0.6020053
-- The CXX compiler identification is AppleClang 6.1.0.6020053
-- Check for working C compiler using: Ninja
-- Check for working C compiler using: Ninja -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler using: Ninja
-- Check for working CXX compiler using: Ninja -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
CMake Error at cmake/modules/LLDBStandalone.cmake:51 (message):
  Please set LLDB_PATH_TO_CLANG_BUILD to the root directory of Clang build or
  install site.
Call Stack (most recent call first):
  CMakeLists.txt:3 (include)


-- Configuring incomplete, errors occurred!
See also "/home/rramacha/src/lldb-build2/CMakeFiles/CMakeOutput.log".

To build successfully, you need to (with or without the patch):

$ cmake -GNinja -DCMAKE_BUILD_TYPE=Debug -DLLDB_PATH_TO_LLVM_SOURCE=~/src/llvm -DLLDB_PATH_TO_LLVM_BUILD=~/src/llvm-build -DLLDB_PATH_TO_CLANG_SOURCE=~/src/clang -DLLDB_PATH_TO_CLANG_BUILD=~/src/clang-build ../lldb

The patch doesn't solve all issues: for instance, what happens when LLDB_PATH_TO_{LLVM,CLANG}_SOURCE isn't suitable? Why can't I query llvm-config and get all these paths? (and hopefully link against the installed version).

But I think it's a step forward. I think we should encourage people to build lldb standalone, so they can iterate faster.

[tfiala]

Okay, this seems reasonable.

cmake/modules/LLDBStandalone.cmake

if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
 
   if (LLDB_PATH_TO_LLVM_SOURCE)
     if (NOT EXISTS "${LLDB_PATH_TO_LLVM_SOURCE}/cmake/config-ix.cmake")
       message(FATAL_ERROR "Please set LLDB_PATH_TO_LLVM_SOURCE to the root "
               "directory of LLVM source code.")
     else()
       get_filename_component(LLVM_MAIN_SRC_DIR ${LLDB_PATH_TO_LLVM_SOURCE}
                              ABSOLUTE)
+      set(LLVM_MAIN_INCLUDE_DIR "${LLVM_MAIN_SRC_DIR}/include")
       list(APPEND CMAKE_MODULE_PATH "${LLVM_MAIN_SRC_DIR}/cmake/modules")
     endif()
   endif()
 
   if (LLDB_PATH_TO_CLANG_SOURCE)
       get_filename_component(CLANG_MAIN_SRC_DIR ${LLDB_PATH_TO_CLANG_SOURCE}
                              ABSOLUTE)
+      set(CLANG_MAIN_INCLUDE_DIR "${CLANG_MAIN_SRC_DIR}/include")
   endif()
 
   list(APPEND CMAKE_MODULE_PATH "${LLDB_PATH_TO_LLVM_BUILD}/share/llvm/cmake")
 
+  if (LLDB_PATH_TO_LLVM_BUILD)
     get_filename_component(PATH_TO_LLVM_BUILD ${LLDB_PATH_TO_LLVM_BUILD}
                            ABSOLUTE)
+  else()
+    message(FATAL_ERROR "Please set LLDB_PATH_TO_LLVM_BUILD to the root "
+            "directory of LLVM build or install site.")
+  endif()
 
+  if (LLDB_PATH_TO_CLANG_BUILD)
     get_filename_component(PATH_TO_CLANG_BUILD ${LLDB_PATH_TO_CLANG_BUILD}
                            ABSOLUTE)
+  else()
+    message(FATAL_ERROR "Please set LLDB_PATH_TO_CLANG_BUILD to the root "
+            "directory of Clang build or install site.")
+  endif()
+
 
   # These variables are used by add_llvm_library.
   set(LLVM_RUNTIME_OUTPUT_INTDIR ${CMAKE_BINARY_DIR}/${CMAKE_CFG_INTDIR}/bin)
   set(LLVM_LIBRARY_OUTPUT_INTDIR ${CMAKE_BINARY_DIR}/${CMAKE_CFG_INTDIR}/lib${LLVM_LIBDIR_SUFFIX})
   set(LLVM_LIBRARY_DIR ${LLVM_LIBRARY_OUTPUT_INTDIR})
 
   include(AddLLVM)
   include(HandleLLVMOptions)
if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
   # Import CMake library targets from LLVM and Clang.
   include("${LLDB_PATH_TO_LLVM_BUILD}/share/llvm/cmake/LLVMConfig.cmake")
   if (EXISTS "${LLDB_PATH_TO_CLANG_BUILD}/share/clang/cmake/ClangConfig.cmake")
       include("${LLDB_PATH_TO_CLANG_BUILD}/share/clang/cmake/ClangConfig.cmake")
   endif()
 
   set(PACKAGE_VERSION "${LLVM_PACKAGE_VERSION}")
 
-  set(LLVM_MAIN_INCLUDE_DIR "${LLVM_MAIN_SRC_DIR}/include")
   set(LLVM_BINARY_DIR ${CMAKE_BINARY_DIR})
 
-  set(CLANG_MAIN_INCLUDE_DIR "${CLANG_MAIN_SRC_DIR}/include")
-
   set(CMAKE_INCLUDE_CURRENT_DIR ON)
   include_directories("${PATH_TO_LLVM_BUILD}/include"
                       "${LLVM_MAIN_INCLUDE_DIR}"
                       "${PATH_TO_CLANG_BUILD}/include"
                       "${CLANG_MAIN_INCLUDE_DIR}"
                       "${CMAKE_CURRENT_SOURCE_DIR}/source")
   link_directories("${PATH_TO_LLVM_BUILD}/lib${LLVM_LIBDIR_SUFFIX}"
                    "${PATH_TO_CLANG_BUILD}/lib${LLVM_LIBDIR_SUFFIX}")
 
   set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/bin)
   set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib${LLVM_LIBDIR_SUFFIX})
   set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib${LLVM_LIBDIR_SUFFIX})
 
   set(LLDB_BUILT_STANDALONE 1)
 endif()