add compile option to force variableFeatures=False

this can be useful to debugging, comparing build time of new vs old build pipeline, or if one wants to ensure no binary changes occur when updating the compiler

Lib/ufo2ft/_compilers/baseCompiler.py

@@ -259,7 +259,9 @@ def _compileNeededSources(self, designSpaceDoc):
 
         # If the feature files are compatible between the sources, we can save
         # time by building a variable feature file right at the end.
-        can_optimize_features = _featuresCompatible(designSpaceDoc)
+        can_optimize_features = self.variableFeatures and _featuresCompatible(
+            designSpaceDoc
+        )
         if can_optimize_features:
             self.logger.info("Features are compatible across masters; building later")
 

Lib/ufo2ft/_compilers/interpolatableOTFCompiler.py

@@ -7,6 +7,7 @@
 from ufo2ft.constants import SPARSE_OTF_MASTER_TABLES, CFFOptimization
 from ufo2ft.outlineCompiler import OutlineOTFCompiler
 from ufo2ft.preProcessor import OTFPreProcessor
+from ufo2ft.util import prune_unknown_kwargs
 
 from .baseCompiler import BaseInterpolatableCompiler
 from .otfCompiler import OTFCompiler
@@ -50,8 +51,7 @@ def compile(self, ufos):
                 ),
             }
             # Remove interpolatable-specific args
-            del args["variableFontNames"]
-            del args["excludeVariationTables"]
+            args = prune_unknown_kwargs(args, OTFCompiler)
             compiler = OTFCompiler(**args)
             self.extraSubstitutions = save_extraSubstitutions
             otfs.append(compiler.compile(ufo))

Lib/ufo2ft/_compilers/variableCFF2sCompiler.py

@@ -17,3 +17,4 @@ class VariableCFF2sCompiler(InterpolatableOTFCompiler):
     cffVersion: int = 2
     optimizeCFF: CFFOptimization = CFFOptimization.SPECIALIZE
     excludeVariationTables: tuple = ()
+    variableFeatures: bool = True

Lib/ufo2ft/_compilers/variableTTFsCompiler.py

@@ -21,3 +21,4 @@ class VariableTTFsCompiler(InterpolatableTTFCompiler):
     autoUseMyMetrics: bool = True
     dropImpliedOnCurves: bool = False
     allQuadratic: bool = True
+    variableFeatures: bool = True