cable: external git info

Problem:

A git commit sha or a branch name change causes relinking of executable targets with silkworm-buildinfo library even if nothing else has changed.

During development (e.g. local Debug builds) it is more important to have fast incremental builds than having the correct git commit sha and a branch name baked into the binary.

Solution:

Add arguments to cable_add_buildinfo_library:
* GIT_DESCRIBE
* GIT_BRANCH
* GIT_ORIGIN_URL

If passed they override corresponding git commands.

cmake/cable/CableBuildInfo.cmake

@@ -22,8 +22,15 @@ include(GNUInstallDirs)
 set(cable_buildinfo_template_dir ${CMAKE_CURRENT_LIST_DIR}/buildinfo)
 
 function(cable_add_buildinfo_library)
-
-    cmake_parse_arguments("" "" PROJECT_NAME;EXPORT "" ${ARGN})
+    set(
+        ARG_NAMES
+        PROJECT_NAME
+        EXPORT
+        GIT_DESCRIBE
+        GIT_BRANCH
+        GIT_ORIGIN_URL
+    )
+    cmake_parse_arguments(PARSE_ARGV 0 "" "" "${ARG_NAMES}" "")
 
     if(NOT _PROJECT_NAME)
         message(FATAL_ERROR "The PROJECT_NAME argument missing")
@@ -55,10 +62,14 @@ function(cable_add_buildinfo_library)
         ${name}-git
         COMMAND ${CMAKE_COMMAND}
         -DGIT=${GIT_EXECUTABLE}
+        -DGIT_DESCRIBE=${_GIT_DESCRIBE}
+        -DGIT_BRANCH=${_GIT_BRANCH}
+        -DGIT_ORIGIN_URL=${_GIT_ORIGIN_URL}
         -DSOURCE_DIR=${PROJECT_SOURCE_DIR}
         -DOUTPUT_DIR=${output_dir}
         -P ${cable_buildinfo_template_dir}/gitinfo.cmake
         BYPRODUCTS ${output_dir}/gitinfo.txt
+        COMMENT "CableBuildInfo: updating gitinfo.txt"
     )
 
     add_custom_command(

cmake/cable/buildinfo/gitinfo.cmake

@@ -4,45 +4,55 @@
 
 # Execute git only if the tool is available.
 if(GIT)
-    execute_process(
-        COMMAND ${GIT} describe --always --long --tags --first-parent --match=v* --abbrev=40 --dirty
-        WORKING_DIRECTORY ${SOURCE_DIR}
-        OUTPUT_VARIABLE gitinfo
-        OUTPUT_STRIP_TRAILING_WHITESPACE
-        ERROR_VARIABLE error
-        ERROR_STRIP_TRAILING_WHITESPACE
-    )
-    if(error)
-        message(WARNING "Git ${error}")
+    if (GIT_DESCRIBE)
+        set(gitdescribe "${GIT_DESCRIBE}")
+    else()
+        execute_process(
+            COMMAND ${GIT} describe --always --long --tags --first-parent --match=v* --abbrev=40 --dirty
+            WORKING_DIRECTORY ${SOURCE_DIR}
+            OUTPUT_VARIABLE gitdescribe
+            OUTPUT_STRIP_TRAILING_WHITESPACE
+            ERROR_VARIABLE error
+            ERROR_STRIP_TRAILING_WHITESPACE
+        )
+        if(error)
+            message(WARNING "Git ${error}")
+        endif()
     endif()
 
-    execute_process(
-        COMMAND ${GIT} rev-parse --abbrev-ref HEAD
-        WORKING_DIRECTORY ${SOURCE_DIR}
-        OUTPUT_VARIABLE gitbranch
-        OUTPUT_STRIP_TRAILING_WHITESPACE
-        ERROR_VARIABLE error
-        ERROR_STRIP_TRAILING_WHITESPACE
-    )
-    if(error)
-        message(WARNING "Git ${error}")
+    if (GIT_BRANCH)
+        set(gitbranch "${GIT_BRANCH}")
     else()
-        set(gitinfo "${gitinfo}\n${gitbranch}")
+        execute_process(
+            COMMAND ${GIT} rev-parse --abbrev-ref HEAD
+            WORKING_DIRECTORY ${SOURCE_DIR}
+            OUTPUT_VARIABLE gitbranch
+            OUTPUT_STRIP_TRAILING_WHITESPACE
+            ERROR_VARIABLE error
+            ERROR_STRIP_TRAILING_WHITESPACE
+        )
+        if(error)
+            message(WARNING "Git ${error}")
+        endif()
     endif()
 
-    execute_process(
-        COMMAND ${GIT} config --get remote.origin.url
-        WORKING_DIRECTORY ${SOURCE_DIR}
-        OUTPUT_VARIABLE gitorigin
-        OUTPUT_STRIP_TRAILING_WHITESPACE
-        ERROR_VARIABLE error
-        ERROR_STRIP_TRAILING_WHITESPACE
-    )
-    if(error)
-        message(WARNING "Git ${error}")
+    if (GIT_ORIGIN_URL)
+        set(gitorigin "${GIT_ORIGIN_URL}")
     else()
-        set(gitinfo "${gitinfo}\n${gitorigin}\n")
+        execute_process(
+            COMMAND ${GIT} config --get remote.origin.url
+            WORKING_DIRECTORY ${SOURCE_DIR}
+            OUTPUT_VARIABLE gitorigin
+            OUTPUT_STRIP_TRAILING_WHITESPACE
+            ERROR_VARIABLE error
+            ERROR_STRIP_TRAILING_WHITESPACE
+        )
+        if(error)
+            message(WARNING "Git ${error}")
+        endif()
     endif()
+
+    set(gitinfo "${gitdescribe}\n${gitbranch}\n${gitorigin}\n")
 endif()
 
 set(gitinfo_file ${OUTPUT_DIR}/gitinfo.txt)