hepmc3: pass `root` variant `cxxstd` as `HEPMC3_CXX_STANDARD` (#44806)

* hepmc3: pass `root` variant `cxxstd` as `HEPMC3_CXX_STANDARD`

* hepmc3: when @:3.2.3 +rootio, depends_on root cxxstd=11

* [@spackbot] updating style on behalf of wdconinc

---------

Co-authored-by: wdconinc <wdconinc@users.noreply.github.com>

1 files changed, 9 insertions, 3 deletions

diff --git a/var/spack/repos/builtin/packages/hepmc3/package.py b/var/spack/repos/builtin/packages/hepmc3/package.py
index a3f96d95c5..15671eef04 100644
--- a/var/spack/repos/builtin/packages/hepmc3/package.py
+++ b/var/spack/repos/builtin/packages/hepmc3/package.py
@@ -44,7 +44,9 @@ class Hepmc3(CMakePackage):
     )
 
     depends_on("cmake@2.8.9:", type="build")
-    depends_on("root", when="+rootio")
+    with when("+rootio"):
+        depends_on("root")
+        depends_on("root cxxstd=11", when="@:3.2.3")
     depends_on("protobuf", when="+protobuf")
     depends_on("python", when="+python")
 
@@ -62,7 +64,7 @@ class Hepmc3(CMakePackage):
             self.define("HEPMC3_ENABLE_TEST", self.run_tests),
         ]
 
-        if "+python" in spec:
+        if spec.satisfies("+python"):
             py_ver = spec["python"].version.up_to(2)
             args.extend(
                 [
@@ -71,7 +73,11 @@ class Hepmc3(CMakePackage):
                 ]
             )
 
-        if "+rootio" in spec:
+        if spec.satisfies("+rootio"):
             args.append(self.define("ROOT_DIR", spec["root"].prefix))
+            if spec.satisfies("@3.2.4:"):
+                args.append(
+                    self.define("HEPMC3_CXX_STANDARD", spec["root"].variants["cxxstd"].value)
+                )
 
         return args