Boost: fix logic for controlling which libs build on Windows (#46414)

Older builds of Boost were failing on Windows because they were
adding --without-... flags for libraries that did not exist in those
versions. So:

* lib variants are updated with version range info (current range
  info for libs is not comprehensive, but represents changes over the
  last few minor versions up to 1.85)
* On Windows, --without-... options are omitted for libraries when they
  don't exist for the version of boost being built. Non-Windows uses
  a different approach, which was not affected because the new libraries
  were not activated by default. It would benefit from similar attention
  though to avoid potential future issues.

1 files changed, 11 insertions, 3 deletions

diff --git a/var/spack/repos/builtin/packages/boost/package.py b/var/spack/repos/builtin/packages/boost/package.py
index 50cd7d5a46..908ea40a89 100644
--- a/var/spack/repos/builtin/packages/boost/package.py
+++ b/var/spack/repos/builtin/packages/boost/package.py
@@ -154,8 +154,12 @@ class Boost(Package):
         "wave",
     ]
 
+    # Add any extra requirements for specific
+    all_libs_opts = {"charconv": {"when": "@1.85.0:"}, "cobalt": {"when": "@1.84.0:"}}
+
     for lib in all_libs:
-        variant(lib, default=False, description="Compile with {0} library".format(lib))
+        lib_opts = all_libs_opts.get(lib, {})
+        variant(lib, default=False, description="Compile with {0} library".format(lib), **lib_opts)
 
     @property
     def libs(self):
@@ -624,9 +628,13 @@ class Boost(Package):
                 options.append("runtime-link=shared")
             else:
                 options.append("runtime-link=static")
+
+            # Any lib that is in self.all_libs AND in the variants dictionary
+            # AND is set to False should be added to options in a --without flag
             for lib in self.all_libs:
-                if f"+{lib}" not in spec:
-                    options.append(f"--without-{lib}")
+                if lib not in self.spec.variants.dict or self.spec.satisfies(f"+{lib}"):
+                    continue
+                options.append(f"--without-{lib}")
 
         if not spec.satisfies("@:1.75 %intel") and not spec.satisfies("platform=windows"):
             # When building any version >= 1.76, the toolset must be specified.