Handle multiple entries in B2_DEFINES

As pointed out by @sdarwin multiple values in `B2_DEFINES` led to a failing build as the scripts only supported a single value for the "new" var usages.
This is a regression from the old usage where `B2_DEFINES: define=FOO=1 define=BAR=2` could be used.
This is now fixed by a small parser function which generates multiple `define=*` entries and additionally now also supports spaces in the define values.
Same is done for `B2_INCLUDE` which has the same issue.

Also includes the change to the CI script from #177 and an additional test in test.cpp to verify that this works.

.github/workflows/old_ci.yml

@@ -55,6 +55,21 @@ jobs:
               B2_LINKFLAGS: linkflags=-fsanitize=undefined linkflags=-fno-sanitize-recover=all linkflags=-fuse-ld=gold
             os: ubuntu-20.04
             install: g++-8
+
+          - name: New var usage, multiple values per key
+            env:
+              B2_CI_VERSION: 1
+              B2_TOOLSET: gcc-8
+              B2_ADDRESS_MODEL: 64
+              B2_LINK: shared,static
+              B2_THREADING: threading=multi,single
+              B2_VARIANT: release
+              B2_DEFINES: BOOST_NO_STRESS_TEST=1 BOOST_IMPORTANT=1 BOOST_ALSO_IMPORTANT="with space"
+              B2_LINKFLAGS: -fsanitize=undefined -fno-sanitize-recover=all -fuse-ld=gold
+              B2_FLAGS: define=BOOST_CI_TEST_DEFINES=1
+            os: ubuntu-20.04
+            install: g++-8
+
           - name: Travis-like coverage collection
             coverage: yes
             env:

ci/enforce.sh

@@ -85,12 +85,33 @@ if [ -z "$B2_CI_VERSION" ]; then
       -j${B2_JOBS}
   )
 else
+  # Generate multiple "option=value" entries from the value of an environment variable
+  # Handles correct splitting and quoting
+  function append_b2_args
+  {
+      local var_name="$1"
+      local option_name="$2"
+      if [ -n "${!var_name}" ]; then
+          while IFS= read -r -d '' value; do
+              # If the value has an assignment and a space we need to quote it
+              if [[ $value == *"="*" "* ]]; then
+                B2_ARGS+=("${option_name}=${value%%=*}=\"${value#*=}\"")
+              else
+                B2_ARGS+=("${option_name}=${value}")
+              fi
+          done < <(echo "${!var_name}" | xargs -n 1 printf '%s\0')
+      fi
+  }
+
   B2_ARGS=(
       ${B2_TOOLSET:+"toolset=$B2_TOOLSET"}
       "cxxstd=$B2_CXXSTD"
       ${B2_CXXFLAGS:+"cxxflags=$B2_CXXFLAGS"}
-      ${B2_DEFINES:+"define=$B2_DEFINES"}
-      ${B2_INCLUDE:+"include=$B2_INCLUDE"}
+  )
+  append_b2_args B2_DEFINES define
+  append_b2_args B2_INCLUDE include
+  B2_ARGS=(
+      "${B2_ARGS[@]}"
       ${B2_LINKFLAGS:+"linkflags=$B2_LINKFLAGS"}
       ${B2_TESTFLAGS}
       ${B2_ADDRESS_MODEL:+address-model=$B2_ADDRESS_MODEL}

test/test.cpp

@@ -17,8 +17,27 @@
 // Check that including a file from the same directory works
 #include "test2.hpp"
 
+// Test of the CI scripts passing the correct defines
+#ifdef BOOST_CI_TEST_DEFINES
+    #ifndef BOOST_NO_STRESS_TEST
+        #error "Missing define BOOST_NO_STRESS_TEST"
+    #endif
+    #ifndef BOOST_IMPORTANT
+        #error "Missing define BOOST_IMPORTANT"
+    #endif
+    #ifndef BOOST_ALSO_IMPORTANT
+        #error "Missing define BOOST_ALSO_IMPORTANT"
+    #endif
+    #define BOOST_CI_STRINGIZE_2(x) #x
+    #define BOOST_CI_STRINGIZE(x) BOOST_CI_STRINGIZE_2(x)
+#endif
+
 int main()
 {
+#ifdef BOOST_CI_TEST_DEFINES
+    const std::string macro_value = BOOST_CI_STRINGIZE(BOOST_ALSO_IMPORTANT);
+    BOOST_TEST_EQ(macro_value, "with space");
+#endif
     const bool isMSVC = MSVC_VALUE;
     std::map<std::string, std::vector<int> > map;
     map["result"].push_back(boost::boost_ci::get_answer());