Merge bitcoin#30856: build: drop obj/ subdirectory for generated build.h

7025942 build: drop superfluous `HAVE_BUILD_INFO` define (Sebastian Falbesoner)
0dd6625 build: drop obj/ subdir for generated build.h, rename to bitcoin-build-info.h (Sebastian Falbesoner)

Pull request description:

  As indicated by the TODO, the obj subdirectory is not needed anymore now for the generated build.h header, since autotools are gone and we don't have in-source builds anymore (see bitcoin#30454, bitcoin#30664). In the second commit the superflous `HAVE_BUILD_INFO` macro is dropped, as suggested in bitcoin#30856 (review).

ACKs for top commit:
  theuni:
    utACK 7025942

Tree-SHA512: 0a3b2cbbcf638344ceb74e5ba5a0fe2b1718427b23a18c8890258db36ce7177006a146178ed88d9c5ae956a5426f3844e86c1f4cca7c40946359742bffda983b

src/CMakeLists.txt

@@ -8,23 +8,15 @@ include(AddWindowsResources)
 configure_file(${PROJECT_SOURCE_DIR}/cmake/bitcoin-config.h.in config/bitcoin-config.h USE_SOURCE_PERMISSIONS @ONLY)
 include_directories(${CMAKE_CURRENT_BINARY_DIR} ${CMAKE_CURRENT_SOURCE_DIR})
 
-# TODO: After the transition from Autotools to CMake, the obj/ subdirectory
-#       could be dropped as its only purpose was to separate a generated header
-#       from source files.
 add_custom_target(generate_build_info
-  BYPRODUCTS ${PROJECT_BINARY_DIR}/src/obj/build.h
-  COMMAND ${CMAKE_COMMAND} -E make_directory ${PROJECT_BINARY_DIR}/src/obj
-  COMMAND ${CMAKE_COMMAND} -DBUILD_INFO_HEADER_PATH=${PROJECT_BINARY_DIR}/src/obj/build.h -DSOURCE_DIR=${PROJECT_SOURCE_DIR} -P ${PROJECT_SOURCE_DIR}/cmake/script/GenerateBuildInfo.cmake
-  COMMENT "Generating obj/build.h"
+  BYPRODUCTS ${PROJECT_BINARY_DIR}/src/bitcoin-build-info.h
+  COMMAND ${CMAKE_COMMAND} -DBUILD_INFO_HEADER_PATH=${PROJECT_BINARY_DIR}/src/bitcoin-build-info.h -DSOURCE_DIR=${PROJECT_SOURCE_DIR} -P ${PROJECT_SOURCE_DIR}/cmake/script/GenerateBuildInfo.cmake
+  COMMENT "Generating bitcoin-build-info.h"
   VERBATIM
 )
 add_library(bitcoin_clientversion OBJECT EXCLUDE_FROM_ALL
   clientversion.cpp
 )
-target_compile_definitions(bitcoin_clientversion
-  PRIVATE
-    HAVE_BUILD_INFO
-)
 target_link_libraries(bitcoin_clientversion
   PRIVATE
     core_interface

src/clientversion.cpp

@@ -23,14 +23,12 @@ using util::Join;
 const std::string CLIENT_NAME("Satoshi");
 
 
-#ifdef HAVE_BUILD_INFO
-#include <obj/build.h>
-// The <obj/build.h>, which is generated by the build environment (cmake/script/GenerateBuildInfo.cmake),
+#include <bitcoin-build-info.h>
+// The <bitcoin-build-info.h>, which is generated by the build environment (cmake/script/GenerateBuildInfo.cmake),
 // could contain only one line of the following:
 //   - "#define BUILD_GIT_TAG ...", if the top commit is tagged
 //   - "#define BUILD_GIT_COMMIT ...", if the top commit is not tagged
 //   - "// No build information available", if proper git information is not available
-#endif
 
 //! git will put "#define GIT_COMMIT_ID ..." on the next line inside archives. $Format:%n#define GIT_COMMIT_ID "%H"$