Make JBMC build optional with cmake

This commit adds an option to CMake, `WITH_JBMC`, that controls whether
the jbmc directory will be built. It is switched on by default,
preserving the current behaviour.

The motivation is to make it as easy as possible for users to get
started with CBMC, especially users who are only interested in the C
front-end and are on Windows, where installing the JDK and Maven is a
painful exercise.

Also updated `COMPILING.md` to note that you can pass `-DWITH_JBMC=OFF`
to cmake to avoid building jbmc.

Author: karkhaz

CMakeLists.txt

@@ -117,7 +117,10 @@ add_subdirectory(src)
 add_subdirectory(regression)
 add_subdirectory(unit)
 
-add_subdirectory(jbmc)
+set(CBMC_CXX_STANDARD 11)
+set(CBMC_CXX_STANDARD_REQUIRED true)
+set(CBMC_XCODE_ATTRIBUTE_CODE_SIGN_IDENTITY
+    "Developer ID Application: Daniel Kroening")
 
 set_target_properties(
     analyses
@@ -152,20 +155,13 @@ set_target_properties(
     util
     xml
 
-    java_bytecode
-    java-models-library
-    jbmc
-    jbmc-lib
-    janalyzer
-    janalyzer-lib
-    jdiff
-    jdiff-lib
-    java-testing-utils
-    java-unit
-    miniz
-
     PROPERTIES
-    CXX_STANDARD 11
-    CXX_STANDARD_REQUIRED true
-    XCODE_ATTRIBUTE_CODE_SIGN_IDENTITY "Developer ID Application: Daniel Kroening"
+    CXX_STANDARD ${CBMC_CXX_STANDARD}
+    CXX_STANDARD_REQUIRED ${CBMC_CXX_STANDARD_REQUIRED}
+    XCODE_ATTRIBUTE_CODE_SIGN_IDENTITY ${CBMC_XCODE_ATTRIBUTE_CODE_SIGN_IDENTITY}
 )
+
+option(WITH_JBMC "Build the JBMC Java front-end" ON)
+if(WITH_JBMC)
+    add_subdirectory(jbmc)
+endif()

COMPILING.md

@@ -219,6 +219,9 @@ require manual modification of build files.
      ```
      You shoud also install [Homebrew](https://brew.sh), after which you can
      run `brew install cmake` to install CMake.
+   - On platforms where installing the Java Development Kit and Maven is
+     difficult, you can avoid needing these dependencies by not building
+     JBMC. Just pass `-DWITH_JBMC=OFF` to cmake in step (4) below.
    - On Windows, ensure you have Visual Studio 2015 or later installed.
      Then, download CMake from the [official download
      page](https://cmake.org/download).

jbmc/CMakeLists.txt

@@ -7,3 +7,22 @@ add_custom_target(java-models-library ALL
     COMMAND cp target/core-models.jar ${CMAKE_CURRENT_SOURCE_DIR}/src/java_bytecode/library/
     WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/lib/java-models-library
 )
+
+set_target_properties(
+    java_bytecode
+    java-models-library
+    jbmc
+    jbmc-lib
+    janalyzer
+    janalyzer-lib
+    jdiff
+    jdiff-lib
+    java-testing-utils
+    java-unit
+    miniz
+
+    PROPERTIES
+    CXX_STANDARD ${CBMC_CXX_STANDARD}
+    CXX_STANDARD_REQUIRED ${CBMC_CXX_STANDARD_REQUIRED}
+    XCODE_ATTRIBUTE_CODE_SIGN_IDENTITY ${CBMC_XCODE_ATTRIBUTE_CODE_SIGN_IDENTITY}
+)