Sqlite package: export api symbols on Windows (#42299)

* Sqlite requires the user to provide a command line arg (DYNAMIC_SHELL)
  to export shared symbols to import lib from .def
* Add other options recommended by Sqlite docs: 
  https://github.com/sqlite/sqlite/blob/master/doc/compile-for-windows.md
  * Some of these options mean we can restore variants that were
    disabled for Windows (fts, functions, rtree).

var/spack/repos/builtin/packages/sqlite/package.py

@@ -4,11 +4,14 @@
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 import os
 import re
+import sys
 from tempfile import NamedTemporaryFile
 
 import spack.platforms
 from spack.package import *
 
+is_windows = sys.platform == "win32"
+
 
 class Sqlite(AutotoolsPackage, NMakePackage):
     """SQLite is a C-language library that implements a small, fast,
@@ -52,19 +55,6 @@ class Sqlite(AutotoolsPackage, NMakePackage):
 
     # no hard readline dep on Windows + no variant support, makefile has minimal to no options
     for plat in ["linux", "darwin", "cray", "freebsd"]:
-        variant(
-            "functions",
-            default=False,
-            description="Provide mathematical and string extension functions for SQL "
-            "queries using the loadable extensions mechanism",
-            when=f"+dynamic_extensions platform={plat}",
-        )
-        variant(
-            "fts",
-            default=True,
-            description="Include fts4 and fts5 support",
-            when=f"platform={plat}",
-        )
         variant(
             "column_metadata",
             default=True,
@@ -77,11 +67,22 @@ class Sqlite(AutotoolsPackage, NMakePackage):
             description="Support loadable extensions",
             when=f"platform={plat}",
         )
-        variant(
+
-            "rtree", default=True, description="Build with Rtree module", when=f"platform={plat}"
-        )
         depends_on("readline", when=f"platform={plat}")
 
+    variant("fts", default=True, description="Include fts4 and fts5 support")
+
+    # functions variant is always available on Windows platform, otherwise is tied
+    # to +dynamic_extensions
+    function_condition = "platform=windows" if is_windows else "+dynamic_extensions"
+    variant(
+        "functions",
+        default=is_windows,
+        description="Provide mathematical and string extension functions for SQL "
+        "queries using the loadable extensions mechanism",
+        when=f"{function_condition}",
+    )
+    variant("rtree", default=True, description="Build with Rtree module")
     depends_on("zlib-api")
     depends_on("tcl", when="platform=windows")
 
@@ -285,6 +286,27 @@ class NMakeBuilder(spack.build_systems.nmake.NMakeBuilder):
     def makefile_name(self):
         return "Makefile.msc"
 
+    def nmake_args(self):
+        enable_fts = "1" if "+fts" in self.spec else "0"
+        enable_rtree = "1" if "+rtree" in self.spec else "0"
+        enable_functions = "1" if "+functions" in self.spec else "0"
+
+        opts = (
+            "OPTS="
+            f"-DSQLITE_ENABLE_FTS3={enable_fts} "
+            f"-DSQLITE_ENABLE_FTS4={enable_fts} "
+            f"-DSQLITE_ENABLE_FTS5={enable_fts} "
+            f"-DSQLITE_ENABLE_RTREE={enable_rtree} "
+            "-DSQLITE_ENABLE_JSON1=1 "
+            "-DSQLITE_ENABLE_GEOPOLY=1 "
+            "-DSQLITE_ENABLE_SESSION=1 "
+            "-DSQLITE_ENABLE_PREUPDATE_HOOK=1 "
+            "-DSQLITE_ENABLE_SERIALIZE=1 "
+            f"-DSQLITE_ENABLE_MATH_FUNCTIONS={enable_functions}"
+        )
+
+        return ["USE_NATIVE_LIBPATHS=1", "DYNAMIC_SHELL=1", opts]
+
     def install(self, pkg, spec, prefix):
         with working_dir(self.build_directory):
             mkdirp(prefix.include)