From 938b29b96c6c06dcd7b0db4d116df24e890fca9d Mon Sep 17 00:00:00 2001
From: Colin Rofls <colin@cmyr.net>
Date: Sun, 27 Oct 2024 14:49:50 -0400
Subject: [PATCH 01/16] FIXUP: add File.is_variable

---
 Lib/gftools/builder/file.py                        | 6 ++++++
 Lib/gftools/builder/recipeproviders/googlefonts.py | 6 +-----
 2 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/Lib/gftools/builder/file.py b/Lib/gftools/builder/file.py
index 7191821a1..1d0b2d0b7 100644
--- a/Lib/gftools/builder/file.py
+++ b/Lib/gftools/builder/file.py
@@ -47,6 +47,12 @@ def is_designspace(self):
     def is_font_source(self):
         return self.is_glyphs or self.is_ufo or self.is_designspace
 
+    @cached_property
+    def is_variable(self) -> bool:
+        return (self.is_glyphs and len(self.gsfont.masters) > 1) or (
+            self.is_designspace and len(self.designspace.sources) > 1
+        )
+
     @cached_property
     def gsfont(self):
         if self.is_glyphs:
diff --git a/Lib/gftools/builder/recipeproviders/googlefonts.py b/Lib/gftools/builder/recipeproviders/googlefonts.py
index 4ab8a4961..dd8240d29 100644
--- a/Lib/gftools/builder/recipeproviders/googlefonts.py
+++ b/Lib/gftools/builder/recipeproviders/googlefonts.py
@@ -227,11 +227,7 @@ def build_all_variables(self):
         if not self.config.get("buildVariable", True):
             return
         for source in self.sources:
-            if (
-                (source.is_glyphs and len(source.gsfont.masters) < 2)
-                or source.is_ufo
-                or (source.is_designspace and len(source.designspace.sources) < 2)
-            ):
+            if not source.is_variable:
                 continue
             italic_ds = None
             if self.config["splitItalic"]:

From 1b44e76e2a79ec73e286573e4831ee675a5bcae2 Mon Sep 17 00:00:00 2001
From: Colin Rofls <colin@cmyr.net>
Date: Mon, 14 Oct 2024 16:29:12 -0400
Subject: [PATCH 02/16] [fontc] Initial support for fontc mode

In the presence of a new CLI flag, the builder will now override certain
operations so that they are driven by fontc.
---
 Lib/gftools/builder/__init__.py               | 25 +++++++--
 Lib/gftools/builder/operations/__init__.py    | 53 ++++++++++++++-----
 .../builder/operations/fontc/__init__.py      |  0
 .../builder/operations/fontc/fontcBuildTTF.py |  6 +++
 .../operations/fontc/fontcBuildVariable.py    |  6 +++
 5 files changed, 72 insertions(+), 18 deletions(-)
 create mode 100644 Lib/gftools/builder/operations/fontc/__init__.py
 create mode 100644 Lib/gftools/builder/operations/fontc/fontcBuildTTF.py
 create mode 100644 Lib/gftools/builder/operations/fontc/fontcBuildVariable.py

diff --git a/Lib/gftools/builder/__init__.py b/Lib/gftools/builder/__init__.py
index afdb9f20f..8ce88ae08 100644
--- a/Lib/gftools/builder/__init__.py
+++ b/Lib/gftools/builder/__init__.py
@@ -17,7 +17,7 @@
 from ninja.ninja_syntax import Writer, escape_path
 
 from gftools.builder.file import File
-from gftools.builder.operations import OperationBase, known_operations
+from gftools.builder.operations import OperationBase, OperationRegistry
 from gftools.builder.operations.copy import Copy
 from gftools.builder.recipeproviders import get_provider
 from gftools.builder.schema import BASE_SCHEMA
@@ -36,7 +36,7 @@ class GFBuilder:
     config: dict
     recipe: Recipe
 
-    def __init__(self, config: Union[dict, str]):
+    def __init__(self, config: Union[dict, str], use_fontc=False):
         if isinstance(config, str):
             parentpath = Path(config).resolve().parent
             with open(config, "r") as file:
@@ -55,6 +55,14 @@ def __init__(self, config: Union[dict, str]):
             self._orig_config = yaml.dump(config)
             self.config = config
 
+        # TODO(colin) we also want to suppress instancing when running fontmake
+        # if we're using it to compare with fontc
+        if use_fontc:
+            # override config to turn not build instances if we're variable
+            if self.config.get("buildVariable", True):
+                self.config["buildStatic"] = False
+
+        self.known_operations = OperationRegistry(use_fontc=use_fontc)
         self.writer = Writer(open("build.ninja", "w"))
         self.named_files = {}
         self.used_operations = set([])
@@ -156,9 +164,10 @@ def glyphs_to_ufo(self, source):
 
     def operation_step_to_object(self, step):
         operation = step.get("operation") or step.get("postprocess")
-        if operation not in known_operations:
+        cls = self.known_operations.get(operation)
+        if cls is None:
             raise ValueError(f"Unknown operation {operation}")
-        cls = known_operations[operation]
+
         if operation not in self.used_operations:
             self.used_operations.add(operation)
             cls.write_rules(self.writer)
@@ -381,6 +390,12 @@ def main(args=None):
         help="Just generate and output recipe from recipe builder",
         action="store_true",
     )
+    parser.add_argument(
+        "--experimental-fontc",
+        help="Use fontc instead of fontmake",
+        action="store_true",
+    )
+
     parser.add_argument("config", help="Path to config file or source file", nargs="+")
     args = parser.parse_args(args)
     yaml_files = []
@@ -404,7 +419,7 @@ def main(args=None):
             raise ValueError("Only one config file can be given for now")
         config = args.config[0]
 
-    pd = GFBuilder(config)
+    pd = GFBuilder(config, use_fontc=args.experimental_fontc)
     if args.generate:
         config = pd.config
         config["recipe"] = pd.recipe
diff --git a/Lib/gftools/builder/operations/__init__.py b/Lib/gftools/builder/operations/__init__.py
index 0b0330735..7f5a2265b 100644
--- a/Lib/gftools/builder/operations/__init__.py
+++ b/Lib/gftools/builder/operations/__init__.py
@@ -8,6 +8,7 @@
 import sys
 from os.path import dirname
 from tempfile import NamedTemporaryFile
+from typing import Dict
 
 from gftools.builder.file import File
 from gftools.utils import shell_quote
@@ -150,17 +151,43 @@ def variables(self):
         return vars
 
 
-known_operations = {}
+class OperationRegistry:
+    def __init__(self, use_fontc: bool):
+        self.known_operations = get_known_operations()
+        self.use_fontc = use_fontc
 
-for mod in pkgutil.iter_modules([dirname(__file__)]):
-    imp = importlib.import_module("gftools.builder.operations." + mod.name)
-    classes = [
-        (name, cls)
-        for name, cls in inspect.getmembers(sys.modules[imp.__name__], inspect.isclass)
-        if "OperationBase" not in name and issubclass(cls, OperationBase)
-    ]
-    if len(classes) > 1:
-        raise ValueError(
-            f"Too many classes in module gftools.builder.operations.{mod.name}"
-        )
-    known_operations[mod.name] = classes[0][1]
+    def get(self, operation_name: str):
+        if self.use_fontc:
+            if operation_name == "buildVariable":
+                # if we import this at the top level it's a circular import error
+                from .fontc.fontcBuildVariable import FontcBuildVariable
+
+                return FontcBuildVariable
+            if operation_name == "buildTTF":
+                from .fontc.fontcBuildTTF import FontcBuildTTF
+
+                return FontcBuildTTF
+
+        return self.known_operations.get(operation_name)
+
+
+def get_known_operations() -> Dict[str, OperationBase]:
+    known_operations = {}
+
+    for mod in pkgutil.iter_modules([dirname(__file__)]):
+        if "fontc" in mod.name:
+            continue
+        imp = importlib.import_module("gftools.builder.operations." + mod.name)
+        classes = [
+            (name, cls)
+            for name, cls in inspect.getmembers(
+                sys.modules[imp.__name__], inspect.isclass
+            )
+            if "OperationBase" not in name and issubclass(cls, OperationBase)
+        ]
+        if len(classes) > 1:
+            raise ValueError(
+                f"Too many classes in module gftools.builder.operations.{mod.name}"
+            )
+        known_operations[mod.name] = classes[0][1]
+    return known_operations
diff --git a/Lib/gftools/builder/operations/fontc/__init__.py b/Lib/gftools/builder/operations/fontc/__init__.py
new file mode 100644
index 000000000..e69de29bb
diff --git a/Lib/gftools/builder/operations/fontc/fontcBuildTTF.py b/Lib/gftools/builder/operations/fontc/fontcBuildTTF.py
new file mode 100644
index 000000000..d7de4a932
--- /dev/null
+++ b/Lib/gftools/builder/operations/fontc/fontcBuildTTF.py
@@ -0,0 +1,6 @@
+from gftools.builder.operations import OperationBase
+
+
+class FontcBuildTTF(OperationBase):
+    description = "Build a TTF from a source file (with fontc)"
+    rule = "fontc -o $out $in"
diff --git a/Lib/gftools/builder/operations/fontc/fontcBuildVariable.py b/Lib/gftools/builder/operations/fontc/fontcBuildVariable.py
new file mode 100644
index 000000000..92fd8e4ac
--- /dev/null
+++ b/Lib/gftools/builder/operations/fontc/fontcBuildVariable.py
@@ -0,0 +1,6 @@
+from gftools.builder.operations import OperationBase
+
+
+class FontcBuildVariable(OperationBase):
+    description = "Build a variable font from a source file (with fontc)"
+    rule = "fontc -o $out $in"

From d28dada5a5f155e9b523a221f0ffac4be997674c Mon Sep 17 00:00:00 2001
From: Colin Rofls <colin@cmyr.net>
Date: Wed, 16 Oct 2024 10:42:37 -0400
Subject: [PATCH 03/16] [fontc] Rewrite fontmake args for fontc

---
 .../builder/operations/fontc/__init__.py      | 44 +++++++++++++++++++
 .../builder/operations/fontc/fontcBuildTTF.py |  6 +--
 .../operations/fontc/fontcBuildVariable.py    |  6 +--
 3 files changed, 50 insertions(+), 6 deletions(-)

diff --git a/Lib/gftools/builder/operations/fontc/__init__.py b/Lib/gftools/builder/operations/fontc/__init__.py
index e69de29bb..2a6744b63 100644
--- a/Lib/gftools/builder/operations/fontc/__init__.py
+++ b/Lib/gftools/builder/operations/fontc/__init__.py
@@ -0,0 +1,44 @@
+from typing import List
+from gftools.builder.operations import OperationBase
+
+
+class FontcOperationBase(OperationBase):
+    @property
+    def variables(self):
+        vars = super().variables
+        args = vars.get("args")
+        if args:
+            vars["args"] = rewrite_fontmake_args_for_fontc(args)
+
+        return vars
+
+
+def rewrite_fontmake_args_for_fontc(args: str) -> str:
+    out_args = []
+    arg_list = args.split()
+    # reverse so we can pop in order
+    arg_list.reverse()
+    while arg_list:
+        out_args.append(rewrite_one_arg(arg_list))
+    return " ".join(out_args)
+
+
+# remove next arg from the front of the list and return its fontc equivalent
+def rewrite_one_arg(args: List[str]) -> str:
+    next_ = args.pop()
+    if next_ == "--filter":
+        filter_ = args.pop()
+        # this means 'retain filters defined in UFO', which... do we even support
+        # that in fontc?
+        if filter_ == "...":
+            pass
+        elif filter_ == "FlattenComponentsFilter":
+            return "--flatten-components"
+        elif filter_ == "DecomposeTransformedComponentsFilter":
+            return "--decompose-transformed-components"
+        else:
+            # glue the filter back together for better reporting below
+            next_ = f"{next_} {filter_}"
+    else:
+        raise ValueError(f"unknown fontmake arg '{next_}'")
+    return ""
diff --git a/Lib/gftools/builder/operations/fontc/fontcBuildTTF.py b/Lib/gftools/builder/operations/fontc/fontcBuildTTF.py
index d7de4a932..96a6e268f 100644
--- a/Lib/gftools/builder/operations/fontc/fontcBuildTTF.py
+++ b/Lib/gftools/builder/operations/fontc/fontcBuildTTF.py
@@ -1,6 +1,6 @@
-from gftools.builder.operations import OperationBase
+from gftools.builder.operations.fontc import FontcOperationBase
 
 
-class FontcBuildTTF(OperationBase):
+class FontcBuildTTF(FontcOperationBase):
     description = "Build a TTF from a source file (with fontc)"
-    rule = "fontc -o $out $in"
+    rule = "fontc -o $out $in $args"
diff --git a/Lib/gftools/builder/operations/fontc/fontcBuildVariable.py b/Lib/gftools/builder/operations/fontc/fontcBuildVariable.py
index 92fd8e4ac..fddc833c9 100644
--- a/Lib/gftools/builder/operations/fontc/fontcBuildVariable.py
+++ b/Lib/gftools/builder/operations/fontc/fontcBuildVariable.py
@@ -1,6 +1,6 @@
-from gftools.builder.operations import OperationBase
+from gftools.builder.operations.fontc import FontcOperationBase
 
 
-class FontcBuildVariable(OperationBase):
+class FontcBuildVariable(FontcOperationBase):
     description = "Build a variable font from a source file (with fontc)"
-    rule = "fontc -o $out $in"
+    rule = "fontc -o $out $in $args"

From 365451b6e2bd2166eb12aeab308b510611fe9516 Mon Sep 17 00:00:00 2001
From: Colin Rofls <colin@cmyr.net>
Date: Wed, 16 Oct 2024 11:36:17 -0400
Subject: [PATCH 04/16] [fontc] Add dummy otf builder

---
 Lib/gftools/builder/__init__.py                       | 6 ++++++
 Lib/gftools/builder/operations/__init__.py            | 4 +++-
 Lib/gftools/builder/operations/fontc/fontcBuildOTF.py | 8 ++++++++
 3 files changed, 17 insertions(+), 1 deletion(-)
 create mode 100644 Lib/gftools/builder/operations/fontc/fontcBuildOTF.py

diff --git a/Lib/gftools/builder/__init__.py b/Lib/gftools/builder/__init__.py
index 8ce88ae08..a2c58fafd 100644
--- a/Lib/gftools/builder/__init__.py
+++ b/Lib/gftools/builder/__init__.py
@@ -58,9 +58,15 @@ def __init__(self, config: Union[dict, str], use_fontc=False):
         # TODO(colin) we also want to suppress instancing when running fontmake
         # if we're using it to compare with fontc
         if use_fontc:
+            self.config["buildWebfont"] = False
             # override config to turn not build instances if we're variable
             if self.config.get("buildVariable", True):
                 self.config["buildStatic"] = False
+            # if the font doesn't explicitly request CFF, just built TT outlines
+            # if the font _only_ wants CFF outlines, we will try to build them
+            # ( but fail on fontc for now )
+            elif self.config.get("buildTTF", True):
+                self.config["buildOTF"] = False
 
         self.known_operations = OperationRegistry(use_fontc=use_fontc)
         self.writer = Writer(open("build.ninja", "w"))
diff --git a/Lib/gftools/builder/operations/__init__.py b/Lib/gftools/builder/operations/__init__.py
index 7f5a2265b..5cd7da85e 100644
--- a/Lib/gftools/builder/operations/__init__.py
+++ b/Lib/gftools/builder/operations/__init__.py
@@ -166,7 +166,9 @@ def get(self, operation_name: str):
             if operation_name == "buildTTF":
                 from .fontc.fontcBuildTTF import FontcBuildTTF
 
-                return FontcBuildTTF
+            if operation_name == "buildOTF":
+                from .fontc.fontcBuildOTF import FontcBuildOTF
+                return FontcBuildOTF
 
         return self.known_operations.get(operation_name)
 
diff --git a/Lib/gftools/builder/operations/fontc/fontcBuildOTF.py b/Lib/gftools/builder/operations/fontc/fontcBuildOTF.py
new file mode 100644
index 000000000..732d5feb0
--- /dev/null
+++ b/Lib/gftools/builder/operations/fontc/fontcBuildOTF.py
@@ -0,0 +1,8 @@
+from gftools.builder.operations.fontc import FontcOperationBase
+
+
+class FontcBuildTTF(FontcOperationBase):
+    description = "Build an OTF from a source file (with fontc)"
+    # the '--cff-outlines' flag does not exit in fontc, so this will
+    # error, which we want
+    rule = "fontc -o $out $in $args --cff-outlines"

From b3723ae9e743c31ed9073230d437ed9f86b908ee Mon Sep 17 00:00:00 2001
From: Colin Rofls <colin@cmyr.net>
Date: Wed, 16 Oct 2024 11:54:29 -0400
Subject: [PATCH 05/16] [fontc] Skip instantiateUfo if running fontc

---
 Lib/gftools/builder/__init__.py                    | 2 ++
 Lib/gftools/builder/recipeproviders/googlefonts.py | 3 ++-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/Lib/gftools/builder/__init__.py b/Lib/gftools/builder/__init__.py
index a2c58fafd..ebb28045b 100644
--- a/Lib/gftools/builder/__init__.py
+++ b/Lib/gftools/builder/__init__.py
@@ -58,6 +58,8 @@ def __init__(self, config: Union[dict, str], use_fontc=False):
         # TODO(colin) we also want to suppress instancing when running fontmake
         # if we're using it to compare with fontc
         if use_fontc:
+            # we stash this flag here to pass it down to the recipe provider
+            self.config["use_fontc"] = use_fontc
             self.config["buildWebfont"] = False
             # override config to turn not build instances if we're variable
             if self.config.get("buildVariable", True):
diff --git a/Lib/gftools/builder/recipeproviders/googlefonts.py b/Lib/gftools/builder/recipeproviders/googlefonts.py
index dd8240d29..7b68ffc37 100644
--- a/Lib/gftools/builder/recipeproviders/googlefonts.py
+++ b/Lib/gftools/builder/recipeproviders/googlefonts.py
@@ -323,7 +323,8 @@ def build_a_static(self, source: File, instance: InstanceDescriptor, output):
         steps = [
             {"source": source.path},
         ]
-        if not source.is_ufo:
+        # if we're running fontc we skip conversion to UFO
+        if not source.is_ufo and not self.config.get('use_fontc', False):
             instancename = instance.name
             if instancename is None:
                 if not instance.familyName or not instance.styleName:

From bea9f76068ef3c1cedb6962ee9cae3d182c8c72f Mon Sep 17 00:00:00 2001
From: Colin Rofls <colin@cmyr.net>
Date: Wed, 16 Oct 2024 12:00:01 -0400
Subject: [PATCH 06/16] [fontc] Add --experimental-simple-output cli option

This does two things:

- it takes a path, where all our final build products will be saved
- it reduces the set of build targets to match what we would build
  with fontc
---
 Lib/gftools/builder/__init__.py               | 38 +++++++++++++++----
 Lib/gftools/builder/operations/__init__.py    |  1 +
 .../builder/recipeproviders/googlefonts.py    |  2 +-
 3 files changed, 32 insertions(+), 9 deletions(-)

diff --git a/Lib/gftools/builder/__init__.py b/Lib/gftools/builder/__init__.py
index ebb28045b..b741765b8 100644
--- a/Lib/gftools/builder/__init__.py
+++ b/Lib/gftools/builder/__init__.py
@@ -15,6 +15,7 @@
 from fontmake.font_project import FontProject
 from ninja import _program
 from ninja.ninja_syntax import Writer, escape_path
+from typing import Union
 
 from gftools.builder.file import File
 from gftools.builder.operations import OperationBase, OperationRegistry
@@ -36,7 +37,12 @@ class GFBuilder:
     config: dict
     recipe: Recipe
 
-    def __init__(self, config: Union[dict, str], use_fontc=False):
+    def __init__(
+        self,
+        config: Union[dict, str],
+        use_fontc=False,
+        simple_outputs=Union[Path, None],
+    ):
         if isinstance(config, str):
             parentpath = Path(config).resolve().parent
             with open(config, "r") as file:
@@ -55,20 +61,24 @@ def __init__(self, config: Union[dict, str], use_fontc=False):
             self._orig_config = yaml.dump(config)
             self.config = config
 
-        # TODO(colin) we also want to suppress instancing when running fontmake
-        # if we're using it to compare with fontc
-        if use_fontc:
+        if use_fontc or simple_outputs:
             # we stash this flag here to pass it down to the recipe provider
             self.config["use_fontc"] = use_fontc
             self.config["buildWebfont"] = False
+            self.config["buildSmallCap"] = False
             # override config to turn not build instances if we're variable
             if self.config.get("buildVariable", True):
                 self.config["buildStatic"] = False
-            # if the font doesn't explicitly request CFF, just built TT outlines
+            # if the font doesn't explicitly request CFF, just build TT outlines
             # if the font _only_ wants CFF outlines, we will try to build them
-            # ( but fail on fontc for now )
+            # ( but fail on fontc for now) (but is this even a thing?)
             elif self.config.get("buildTTF", True):
                 self.config["buildOTF"] = False
+        if simple_outputs:
+            # we dump everything into one dir in this case
+            self.config["outputDir"] = str(simple_outputs)
+            self.config["ttDir"] = str(simple_outputs)
+            self.config["otDir"] = str(simple_outputs)
 
         self.known_operations = OperationRegistry(use_fontc=use_fontc)
         self.writer = Writer(open("build.ninja", "w"))
@@ -175,7 +185,6 @@ def operation_step_to_object(self, step):
         cls = self.known_operations.get(operation)
         if cls is None:
             raise ValueError(f"Unknown operation {operation}")
-
         if operation not in self.used_operations:
             self.used_operations.add(operation)
             cls.write_rules(self.writer)
@@ -404,8 +413,17 @@ def main(args=None):
         action="store_true",
     )
 
+    parser.add_argument(
+        "--experimental-simple-output",
+        help="generate a reduced set of targets, and copy them to the provided directory",
+        type=Path,
+    )
+
     parser.add_argument("config", help="Path to config file or source file", nargs="+")
     args = parser.parse_args(args)
+    if args.experimental_simple_output:
+        # get the abs path because we use cwd later and relative paths will break
+        args.experimental_simple_output = args.experimental_simple_output.absolute()
     yaml_files = []
     source_files = []
     for config in args.config:
@@ -427,7 +445,11 @@ def main(args=None):
             raise ValueError("Only one config file can be given for now")
         config = args.config[0]
 
-    pd = GFBuilder(config, use_fontc=args.experimental_fontc)
+    pd = GFBuilder(
+        config,
+        use_fontc=args.experimental_fontc,
+        simple_outputs=args.experimental_simple_output,
+    )
     if args.generate:
         config = pd.config
         config["recipe"] = pd.recipe
diff --git a/Lib/gftools/builder/operations/__init__.py b/Lib/gftools/builder/operations/__init__.py
index 5cd7da85e..029bc81c0 100644
--- a/Lib/gftools/builder/operations/__init__.py
+++ b/Lib/gftools/builder/operations/__init__.py
@@ -168,6 +168,7 @@ def get(self, operation_name: str):
 
             if operation_name == "buildOTF":
                 from .fontc.fontcBuildOTF import FontcBuildOTF
+
                 return FontcBuildOTF
 
         return self.known_operations.get(operation_name)
diff --git a/Lib/gftools/builder/recipeproviders/googlefonts.py b/Lib/gftools/builder/recipeproviders/googlefonts.py
index 7b68ffc37..38b2e7d43 100644
--- a/Lib/gftools/builder/recipeproviders/googlefonts.py
+++ b/Lib/gftools/builder/recipeproviders/googlefonts.py
@@ -324,7 +324,7 @@ def build_a_static(self, source: File, instance: InstanceDescriptor, output):
             {"source": source.path},
         ]
         # if we're running fontc we skip conversion to UFO
-        if not source.is_ufo and not self.config.get('use_fontc', False):
+        if not source.is_ufo and not self.config.get("use_fontc", False):
             instancename = instance.name
             if instancename is None:
                 if not instance.familyName or not instance.styleName:

From 4a59df718e6f807de3cec12e38fb6857afd142cd Mon Sep 17 00:00:00 2001
From: Colin Rofls <colin@cmyr.net>
Date: Fri, 25 Oct 2024 13:28:14 -0400
Subject: [PATCH 07/16] [fontc] Pass path to fontc executable via CLI

this requires an ugly global in order to expose this to the relevant
operations, but that was the best solution I could come up with.
---
 Lib/gftools/builder/__init__.py                       |  9 +++++++--
 Lib/gftools/builder/operations/fontc/__init__.py      | 11 +++++++++++
 Lib/gftools/builder/operations/fontc/fontcBuildOTF.py |  2 +-
 Lib/gftools/builder/operations/fontc/fontcBuildTTF.py |  2 +-
 .../builder/operations/fontc/fontcBuildVariable.py    |  2 +-
 5 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/Lib/gftools/builder/__init__.py b/Lib/gftools/builder/__init__.py
index b741765b8..80d656acc 100644
--- a/Lib/gftools/builder/__init__.py
+++ b/Lib/gftools/builder/__init__.py
@@ -9,6 +9,7 @@
 from tempfile import NamedTemporaryFile, gettempdir
 from typing import Any, Dict, List, Union
 
+from gftools.builder.operations.fontc import set_global_fontc_path
 import networkx as nx
 import strictyaml
 import yaml
@@ -409,8 +410,8 @@ def main(args=None):
     )
     parser.add_argument(
         "--experimental-fontc",
-        help="Use fontc instead of fontmake",
-        action="store_true",
+        help=f"Use fontc instead of fontmake. Argument is path to the fontc executable",
+        type=Path,
     )
 
     parser.add_argument(
@@ -424,6 +425,10 @@ def main(args=None):
     if args.experimental_simple_output:
         # get the abs path because we use cwd later and relative paths will break
         args.experimental_simple_output = args.experimental_simple_output.absolute()
+    if args.experimental_fontc:
+        fontc_path = Path(args.experimental_fontc).resolve()
+        assert fontc_path.is_file(), f"{fontc_path} is not a file"
+        set_global_fontc_path(Path(fontc_path))
     yaml_files = []
     source_files = []
     for config in args.config:
diff --git a/Lib/gftools/builder/operations/fontc/__init__.py b/Lib/gftools/builder/operations/fontc/__init__.py
index 2a6744b63..983d41bcc 100644
--- a/Lib/gftools/builder/operations/fontc/__init__.py
+++ b/Lib/gftools/builder/operations/fontc/__init__.py
@@ -1,11 +1,22 @@
+from pathlib import Path
 from typing import List
 from gftools.builder.operations import OperationBase
 
+FONTC_PATH = "FONTC_PATH_NOT_SET"
+
+
+# should only be called once, from main, before doing anything else. This is a
+# relatively non-invasive way to smuggle this value into FontcOperationBase
+def set_global_fontc_path(path: Path):
+    global FONTC_PATH
+    FONTC_PATH = path
+
 
 class FontcOperationBase(OperationBase):
     @property
     def variables(self):
         vars = super().variables
+        vars["fontc_path"] = FONTC_PATH
         args = vars.get("args")
         if args:
             vars["args"] = rewrite_fontmake_args_for_fontc(args)
diff --git a/Lib/gftools/builder/operations/fontc/fontcBuildOTF.py b/Lib/gftools/builder/operations/fontc/fontcBuildOTF.py
index 732d5feb0..cf4834db1 100644
--- a/Lib/gftools/builder/operations/fontc/fontcBuildOTF.py
+++ b/Lib/gftools/builder/operations/fontc/fontcBuildOTF.py
@@ -5,4 +5,4 @@ class FontcBuildTTF(FontcOperationBase):
     description = "Build an OTF from a source file (with fontc)"
     # the '--cff-outlines' flag does not exit in fontc, so this will
     # error, which we want
-    rule = "fontc -o $out $in $args --cff-outlines"
+    rule = "$fontc_path -o $out $in $args --cff-outlines"
diff --git a/Lib/gftools/builder/operations/fontc/fontcBuildTTF.py b/Lib/gftools/builder/operations/fontc/fontcBuildTTF.py
index 96a6e268f..a28c450b5 100644
--- a/Lib/gftools/builder/operations/fontc/fontcBuildTTF.py
+++ b/Lib/gftools/builder/operations/fontc/fontcBuildTTF.py
@@ -3,4 +3,4 @@
 
 class FontcBuildTTF(FontcOperationBase):
     description = "Build a TTF from a source file (with fontc)"
-    rule = "fontc -o $out $in $args"
+    rule = "$fontc_path -o $out $in $args"
diff --git a/Lib/gftools/builder/operations/fontc/fontcBuildVariable.py b/Lib/gftools/builder/operations/fontc/fontcBuildVariable.py
index fddc833c9..abe725046 100644
--- a/Lib/gftools/builder/operations/fontc/fontcBuildVariable.py
+++ b/Lib/gftools/builder/operations/fontc/fontcBuildVariable.py
@@ -3,4 +3,4 @@
 
 class FontcBuildVariable(FontcOperationBase):
     description = "Build a variable font from a source file (with fontc)"
-    rule = "fontc -o $out $in $args"
+    rule = f"$fontc_path -o $out $in $args"

From fa3852da8783b2daf9084f22b36f80c1ade96f1e Mon Sep 17 00:00:00 2001
From: Colin Rofls <colin@cmyr.net>
Date: Fri, 25 Oct 2024 15:47:57 -0400
Subject: [PATCH 08/16] [fontc] Move fontc config logic into separate module

---
 Lib/gftools/builder/__init__.py | 41 ++++--------------------
 Lib/gftools/builder/fontc.py    | 57 +++++++++++++++++++++++++++++++++
 2 files changed, 63 insertions(+), 35 deletions(-)
 create mode 100644 Lib/gftools/builder/fontc.py

diff --git a/Lib/gftools/builder/__init__.py b/Lib/gftools/builder/__init__.py
index 80d656acc..931e97b26 100644
--- a/Lib/gftools/builder/__init__.py
+++ b/Lib/gftools/builder/__init__.py
@@ -9,7 +9,7 @@
 from tempfile import NamedTemporaryFile, gettempdir
 from typing import Any, Dict, List, Union
 
-from gftools.builder.operations.fontc import set_global_fontc_path
+from gftools.builder.fontc import FontcArgs
 import networkx as nx
 import strictyaml
 import yaml
@@ -41,8 +41,7 @@ class GFBuilder:
     def __init__(
         self,
         config: Union[dict, str],
-        use_fontc=False,
-        simple_outputs=Union[Path, None],
+        fontc_args=FontcArgs(None),
     ):
         if isinstance(config, str):
             parentpath = Path(config).resolve().parent
@@ -61,27 +60,9 @@ def __init__(
         else:
             self._orig_config = yaml.dump(config)
             self.config = config
+        fontc_args.modify_config(self.config)
 
-        if use_fontc or simple_outputs:
-            # we stash this flag here to pass it down to the recipe provider
-            self.config["use_fontc"] = use_fontc
-            self.config["buildWebfont"] = False
-            self.config["buildSmallCap"] = False
-            # override config to turn not build instances if we're variable
-            if self.config.get("buildVariable", True):
-                self.config["buildStatic"] = False
-            # if the font doesn't explicitly request CFF, just build TT outlines
-            # if the font _only_ wants CFF outlines, we will try to build them
-            # ( but fail on fontc for now) (but is this even a thing?)
-            elif self.config.get("buildTTF", True):
-                self.config["buildOTF"] = False
-        if simple_outputs:
-            # we dump everything into one dir in this case
-            self.config["outputDir"] = str(simple_outputs)
-            self.config["ttDir"] = str(simple_outputs)
-            self.config["otDir"] = str(simple_outputs)
-
-        self.known_operations = OperationRegistry(use_fontc=use_fontc)
+        self.known_operations = OperationRegistry(use_fontc=fontc_args.use_fontc)
         self.writer = Writer(open("build.ninja", "w"))
         self.named_files = {}
         self.used_operations = set([])
@@ -422,13 +403,7 @@ def main(args=None):
 
     parser.add_argument("config", help="Path to config file or source file", nargs="+")
     args = parser.parse_args(args)
-    if args.experimental_simple_output:
-        # get the abs path because we use cwd later and relative paths will break
-        args.experimental_simple_output = args.experimental_simple_output.absolute()
-    if args.experimental_fontc:
-        fontc_path = Path(args.experimental_fontc).resolve()
-        assert fontc_path.is_file(), f"{fontc_path} is not a file"
-        set_global_fontc_path(Path(fontc_path))
+    fontc_args = FontcArgs(args)
     yaml_files = []
     source_files = []
     for config in args.config:
@@ -450,11 +425,7 @@ def main(args=None):
             raise ValueError("Only one config file can be given for now")
         config = args.config[0]
 
-    pd = GFBuilder(
-        config,
-        use_fontc=args.experimental_fontc,
-        simple_outputs=args.experimental_simple_output,
-    )
+    pd = GFBuilder(config, fontc_args=fontc_args)
     if args.generate:
         config = pd.config
         config["recipe"] = pd.recipe
diff --git a/Lib/gftools/builder/fontc.py b/Lib/gftools/builder/fontc.py
new file mode 100644
index 000000000..9a717126b
--- /dev/null
+++ b/Lib/gftools/builder/fontc.py
@@ -0,0 +1,57 @@
+"""functionality for running fontc via gftools
+
+This mostly exists so that we can keep as much of the fontc logic in one place,
+and not need to dirty up anything else.
+"""
+
+from argparse import Namespace
+from pathlib import Path
+from typing import Union
+
+from gftools.builder.operations.fontc import set_global_fontc_path
+
+
+class FontcArgs:
+    simple_output_path: Union[Path, None]
+    fontc_bin_path: Union[Path, None]
+
+    # init with 'None' returns a default obj where everything is None
+    def __init__(self, args: Union[Namespace, None]) -> None:
+        if not args:
+            return None
+        self.simple_output_path = abspath(args.experimental_simple_output)
+        self.fontc_bin_path = abspath(args.experimental_fontc)
+        if self.fontc_bin_path:
+            if not self.fontc_bin_path.is_file():
+                raise ValueError(f"fontc does not exist at {self.fontc_bin_path}")
+            set_global_fontc_path(self.fontc_bin_path)
+
+    @property
+    def use_fontc(self) -> bool:
+        return self.fontc_bin_path is not None
+
+    # update the config dictionary based on our special needs
+    def modify_config(self, config: dict):
+        if self.fontc_bin_path or self.simple_output_path:
+            # we stash this flag here to pass it down to the recipe provider
+            config["use_fontc"] = self.fontc_bin_path
+            config["buildWebfont"] = False
+            config["buildSmallCap"] = False
+            # override config to turn not build instances if we're variable
+            if config.get("buildVariable", True):
+                config["buildStatic"] = False
+            # if the font doesn't explicitly request CFF, just build TT outlines
+            # if the font _only_ wants CFF outlines, we will try to build them
+            # ( but fail on fontc for now) (but is this even a thing?)
+            elif config.get("buildTTF", True):
+                config["buildOTF"] = False
+        if self.simple_output_path:
+            output_dir = str(self.simple_output_path)
+            # we dump everything into one dir in this case
+            config["outputDir"] = str(output_dir)
+            config["ttDir"] = str(output_dir)
+            config["otDir"] = str(output_dir)
+
+
+def abspath(path: Union[Path, None]) -> Union[Path, None]:
+    return path.resolve() if path else None

From b40e0b326f8aab1257a7a5d1b40ffc3331024a86 Mon Sep 17 00:00:00 2001
From: Colin Rofls <colin@cmyr.net>
Date: Fri, 25 Oct 2024 15:58:29 -0400
Subject: [PATCH 09/16] [fontc] Add --experimental-single-source flag

This instructs gftools to only build the single named source file.
---
 Lib/gftools/builder/__init__.py |  8 +++++++-
 Lib/gftools/builder/fontc.py    | 10 ++++++++++
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/Lib/gftools/builder/__init__.py b/Lib/gftools/builder/__init__.py
index 931e97b26..9eca24080 100644
--- a/Lib/gftools/builder/__init__.py
+++ b/Lib/gftools/builder/__init__.py
@@ -7,7 +7,7 @@
 from os import chdir
 from pathlib import Path
 from tempfile import NamedTemporaryFile, gettempdir
-from typing import Any, Dict, List, Union
+from typing import Any, Dict, List, Tuple, Union
 
 from gftools.builder.fontc import FontcArgs
 import networkx as nx
@@ -401,6 +401,12 @@ def main(args=None):
         type=Path,
     )
 
+    parser.add_argument(
+        "--experimental-single-source",
+        help="only compile the single named source file",
+        type=str,
+    )
+
     parser.add_argument("config", help="Path to config file or source file", nargs="+")
     args = parser.parse_args(args)
     fontc_args = FontcArgs(args)
diff --git a/Lib/gftools/builder/fontc.py b/Lib/gftools/builder/fontc.py
index 9a717126b..0db9c3400 100644
--- a/Lib/gftools/builder/fontc.py
+++ b/Lib/gftools/builder/fontc.py
@@ -14,6 +14,7 @@
 class FontcArgs:
     simple_output_path: Union[Path, None]
     fontc_bin_path: Union[Path, None]
+    single_source: Union[str, None]
 
     # init with 'None' returns a default obj where everything is None
     def __init__(self, args: Union[Namespace, None]) -> None:
@@ -21,6 +22,7 @@ def __init__(self, args: Union[Namespace, None]) -> None:
             return None
         self.simple_output_path = abspath(args.experimental_simple_output)
         self.fontc_bin_path = abspath(args.experimental_fontc)
+        self.single_source = args.experimental_single_source
         if self.fontc_bin_path:
             if not self.fontc_bin_path.is_file():
                 raise ValueError(f"fontc does not exist at {self.fontc_bin_path}")
@@ -51,6 +53,14 @@ def modify_config(self, config: dict):
             config["outputDir"] = str(output_dir)
             config["ttDir"] = str(output_dir)
             config["otDir"] = str(output_dir)
+        if self.single_source:
+            filtered_sources = [s for s in config["sources"] if self.single_source in s]
+            n_sources = len(filtered_sources)
+            if n_sources != 1:
+                raise ValueError(
+                    f"--exerimental-single-source {self.single_source} must match exactly one of {config['sources']} (matched {n_sources}) "
+                )
+            config["sources"] = filtered_sources
 
 
 def abspath(path: Union[Path, None]) -> Union[Path, None]:

From 8e3c626e05a08816c6261a31b9e1916a0341260a Mon Sep 17 00:00:00 2001
From: Colin Rofls <colin@cmyr.net>
Date: Fri, 25 Oct 2024 17:17:09 -0400
Subject: [PATCH 10/16] [fontc] Code review and fixups

---
 Lib/gftools/builder/fontc.py                     | 16 +++++++++-------
 Lib/gftools/builder/operations/fontc/__init__.py |  9 +++++----
 2 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/Lib/gftools/builder/fontc.py b/Lib/gftools/builder/fontc.py
index 0db9c3400..b96442279 100644
--- a/Lib/gftools/builder/fontc.py
+++ b/Lib/gftools/builder/fontc.py
@@ -1,7 +1,10 @@
 """functionality for running fontc via gftools
 
-This mostly exists so that we can keep as much of the fontc logic in one place,
-and not need to dirty up anything else.
+gftools has a few special flags that allow it to use fontc, an alternative
+font compiler (https://github.com/googlefonts/fontc).
+
+This module exists to keep the logic related to fontc in one place, and not
+dirty up everything else.
 """
 
 from argparse import Namespace
@@ -12,14 +15,13 @@
 
 
 class FontcArgs:
-    simple_output_path: Union[Path, None]
-    fontc_bin_path: Union[Path, None]
-    single_source: Union[str, None]
-
     # init with 'None' returns a default obj where everything is None
     def __init__(self, args: Union[Namespace, None]) -> None:
         if not args:
-            return None
+            self.simple_output_path = None
+            self.fontc_bin_path = None
+            self.single_source = None
+            return
         self.simple_output_path = abspath(args.experimental_simple_output)
         self.fontc_bin_path = abspath(args.experimental_fontc)
         self.single_source = args.experimental_single_source
diff --git a/Lib/gftools/builder/operations/fontc/__init__.py b/Lib/gftools/builder/operations/fontc/__init__.py
index 983d41bcc..a0f06b6e5 100644
--- a/Lib/gftools/builder/operations/fontc/__init__.py
+++ b/Lib/gftools/builder/operations/fontc/__init__.py
@@ -2,21 +2,22 @@
 from typing import List
 from gftools.builder.operations import OperationBase
 
-FONTC_PATH = "FONTC_PATH_NOT_SET"
+_FONTC_PATH = None
 
 
 # should only be called once, from main, before doing anything else. This is a
 # relatively non-invasive way to smuggle this value into FontcOperationBase
 def set_global_fontc_path(path: Path):
-    global FONTC_PATH
-    FONTC_PATH = path
+    global _FONTC_PATH
+    assert _FONTC_PATH is None, "set_global_fontc_path should only be called once"
+    _FONTC_PATH = path
 
 
 class FontcOperationBase(OperationBase):
     @property
     def variables(self):
         vars = super().variables
-        vars["fontc_path"] = FONTC_PATH
+        vars["fontc_path"] = _FONTC_PATH
         args = vars.get("args")
         if args:
             vars["args"] = rewrite_fontmake_args_for_fontc(args)

From 1cf3b20496c16c0e40f50aa8130ceabd60d1d9e4 Mon Sep 17 00:00:00 2001
From: Colin Rofls <colin@cmyr.net>
Date: Sun, 27 Oct 2024 14:53:07 -0400
Subject: [PATCH 11/16] [fontc] More careful check for variable source

---
 Lib/gftools/builder/fontc.py | 28 +++++++++++++++++++---------
 1 file changed, 19 insertions(+), 9 deletions(-)

diff --git a/Lib/gftools/builder/fontc.py b/Lib/gftools/builder/fontc.py
index b96442279..e2a92c521 100644
--- a/Lib/gftools/builder/fontc.py
+++ b/Lib/gftools/builder/fontc.py
@@ -11,6 +11,7 @@
 from pathlib import Path
 from typing import Union
 
+from gftools.builder.file import File
 from gftools.builder.operations.fontc import set_global_fontc_path
 
 
@@ -36,13 +37,22 @@ def use_fontc(self) -> bool:
 
     # update the config dictionary based on our special needs
     def modify_config(self, config: dict):
+        if self.single_source:
+            filtered_sources = [s for s in config["sources"] if self.single_source in s]
+            n_sources = len(filtered_sources)
+            if n_sources != 1:
+                raise ValueError(
+                    f"--exerimental-single-source {self.single_source} must match exactly one of {config['sources']} (matched {n_sources}) "
+                )
+            config["sources"] = filtered_sources
+
         if self.fontc_bin_path or self.simple_output_path:
             # we stash this flag here to pass it down to the recipe provider
             config["use_fontc"] = self.fontc_bin_path
             config["buildWebfont"] = False
             config["buildSmallCap"] = False
             # override config to turn not build instances if we're variable
-            if config.get("buildVariable", True):
+            if self.will_build_variable_font(config):
                 config["buildStatic"] = False
             # if the font doesn't explicitly request CFF, just build TT outlines
             # if the font _only_ wants CFF outlines, we will try to build them
@@ -55,14 +65,14 @@ def modify_config(self, config: dict):
             config["outputDir"] = str(output_dir)
             config["ttDir"] = str(output_dir)
             config["otDir"] = str(output_dir)
-        if self.single_source:
-            filtered_sources = [s for s in config["sources"] if self.single_source in s]
-            n_sources = len(filtered_sources)
-            if n_sources != 1:
-                raise ValueError(
-                    f"--exerimental-single-source {self.single_source} must match exactly one of {config['sources']} (matched {n_sources}) "
-                )
-            config["sources"] = filtered_sources
+
+    def will_build_variable_font(self, config: dict) -> bool:
+        # if config explicitly says dont build variable, believe it
+        if not config.get("buildVariable", True):
+            return False
+
+        source = File(config["sources"][0])
+        return source.is_variable
 
 
 def abspath(path: Union[Path, None]) -> Union[Path, None]:

From 7a2be4d83f0631e71ffa1cbdf2a7b24c3bfe5100 Mon Sep 17 00:00:00 2001
From: Colin Rofls <colin@cmyr.net>
Date: Sun, 27 Oct 2024 16:14:55 -0400
Subject: [PATCH 12/16] [fontc] Fixups: don't split italic, set vfDir

---
 Lib/gftools/builder/fontc.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Lib/gftools/builder/fontc.py b/Lib/gftools/builder/fontc.py
index e2a92c521..ad389e017 100644
--- a/Lib/gftools/builder/fontc.py
+++ b/Lib/gftools/builder/fontc.py
@@ -51,6 +51,7 @@ def modify_config(self, config: dict):
             config["use_fontc"] = self.fontc_bin_path
             config["buildWebfont"] = False
             config["buildSmallCap"] = False
+            config["splitItalic"] = False
             # override config to turn not build instances if we're variable
             if self.will_build_variable_font(config):
                 config["buildStatic"] = False
@@ -65,6 +66,7 @@ def modify_config(self, config: dict):
             config["outputDir"] = str(output_dir)
             config["ttDir"] = str(output_dir)
             config["otDir"] = str(output_dir)
+            config["vfDir"] = str(output_dir)
 
     def will_build_variable_font(self, config: dict) -> bool:
         # if config explicitly says dont build variable, believe it

From ebad92951e6bfd8c72a547da1cee95c9708ba1df Mon Sep 17 00:00:00 2001
From: Colin Rofls <colin@cmyr.net>
Date: Wed, 30 Oct 2024 13:14:52 -0400
Subject: [PATCH 13/16] [fontc] Use unique names for ninja files

This way if we are running multiple instances of gftools agains the same
sources, we aren't overwriting each other's build files.
---
 Lib/gftools/builder/__init__.py | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/Lib/gftools/builder/__init__.py b/Lib/gftools/builder/__init__.py
index 9eca24080..5c12c87c5 100644
--- a/Lib/gftools/builder/__init__.py
+++ b/Lib/gftools/builder/__init__.py
@@ -7,7 +7,8 @@
 from os import chdir
 from pathlib import Path
 from tempfile import NamedTemporaryFile, gettempdir
-from typing import Any, Dict, List, Tuple, Union
+import time
+from typing import Any, Dict, List, Union
 
 from gftools.builder.fontc import FontcArgs
 import networkx as nx
@@ -63,7 +64,8 @@ def __init__(
         fontc_args.modify_config(self.config)
 
         self.known_operations = OperationRegistry(use_fontc=fontc_args.use_fontc)
-        self.writer = Writer(open("build.ninja", "w"))
+        self.ninja_file_name = f"build-{time.time_ns()}.ninja"
+        self.writer = Writer(open(self.ninja_file_name, "w"))
         self.named_files = {}
         self.used_operations = set([])
         self.graph = nx.DiGraph()
@@ -336,7 +338,9 @@ def walk_graph(self):
     def draw_graph(self):
         import pydot
 
-        dot = subprocess.run(["ninja", "-t", "graph"], capture_output=True)
+        dot = subprocess.run(
+            ["ninja", "-t", "graph", "-f", self.ninja_file_name], capture_output=True
+        )
         graphs = pydot.graph_from_dot_data(dot.stdout.decode("utf-8"))
         targets = self.recipe.keys()
         if graphs and graphs[0]:
@@ -362,7 +366,7 @@ def clean(self):
             if cleanUp == True:
                 print("Cleaning up temporary files...")
 
-                for file in ["./build.ninja", "./.ninja_log"]:
+                for file in [self.ninja_file_name, "./.ninja_log"]:
                     if os.path.exists(file):
                         os.remove(file)
 
@@ -444,4 +448,4 @@ def main(args=None):
         pd.draw_graph()
     if not args.no_ninja:
         atexit.register(pd.clean)
-        raise SystemExit(_program("ninja", []))
+        raise SystemExit(_program("ninja", ["-f", pd.ninja_file_name]))

From f14c7bc4e5e17b3262297c1f64d63a0ac717d4c0 Mon Sep 17 00:00:00 2001
From: Colin Rofls <colin@cmyr.net>
Date: Thu, 31 Oct 2024 11:58:05 -0400
Subject: [PATCH 14/16] [fontc] Actually build static fonts with fontc

---
 Lib/gftools/builder/operations/__init__.py            | 2 ++
 Lib/gftools/builder/operations/fontc/fontcBuildOTF.py | 2 +-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/Lib/gftools/builder/operations/__init__.py b/Lib/gftools/builder/operations/__init__.py
index 029bc81c0..ca4d3cd05 100644
--- a/Lib/gftools/builder/operations/__init__.py
+++ b/Lib/gftools/builder/operations/__init__.py
@@ -166,6 +166,8 @@ def get(self, operation_name: str):
             if operation_name == "buildTTF":
                 from .fontc.fontcBuildTTF import FontcBuildTTF
 
+                return FontcBuildTTF
+
             if operation_name == "buildOTF":
                 from .fontc.fontcBuildOTF import FontcBuildOTF
 
diff --git a/Lib/gftools/builder/operations/fontc/fontcBuildOTF.py b/Lib/gftools/builder/operations/fontc/fontcBuildOTF.py
index cf4834db1..8ca3c8523 100644
--- a/Lib/gftools/builder/operations/fontc/fontcBuildOTF.py
+++ b/Lib/gftools/builder/operations/fontc/fontcBuildOTF.py
@@ -1,7 +1,7 @@
 from gftools.builder.operations.fontc import FontcOperationBase
 
 
-class FontcBuildTTF(FontcOperationBase):
+class FontcBuildOTF(FontcOperationBase):
     description = "Build an OTF from a source file (with fontc)"
     # the '--cff-outlines' flag does not exit in fontc, so this will
     # error, which we want

From 4d011a3da2bff2560dc20acaa5aeaa9fa452a084 Mon Sep 17 00:00:00 2001
From: Colin Rofls <colin@cmyr.net>
Date: Thu, 31 Oct 2024 12:22:51 -0400
Subject: [PATCH 15/16] [fontc] Set --no-production-names

---
 Lib/gftools/builder/fontc.py                     | 4 ++++
 Lib/gftools/builder/operations/fontc/__init__.py | 2 ++
 2 files changed, 6 insertions(+)

diff --git a/Lib/gftools/builder/fontc.py b/Lib/gftools/builder/fontc.py
index ad389e017..9d951554f 100644
--- a/Lib/gftools/builder/fontc.py
+++ b/Lib/gftools/builder/fontc.py
@@ -52,6 +52,10 @@ def modify_config(self, config: dict):
             config["buildWebfont"] = False
             config["buildSmallCap"] = False
             config["splitItalic"] = False
+            # set --no-production-names, because it's easier to debug
+            extra_args = config.get("extraFontmakeArgs") or ""
+            extra_args += " --no-production-names"
+            config["extraFontmakeArgs"] = extra_args
             # override config to turn not build instances if we're variable
             if self.will_build_variable_font(config):
                 config["buildStatic"] = False
diff --git a/Lib/gftools/builder/operations/fontc/__init__.py b/Lib/gftools/builder/operations/fontc/__init__.py
index a0f06b6e5..e25cad2ae 100644
--- a/Lib/gftools/builder/operations/fontc/__init__.py
+++ b/Lib/gftools/builder/operations/fontc/__init__.py
@@ -51,6 +51,8 @@ def rewrite_one_arg(args: List[str]) -> str:
         else:
             # glue the filter back together for better reporting below
             next_ = f"{next_} {filter_}"
+    elif next_ == "--no-production-names":
+        return next_
     else:
         raise ValueError(f"unknown fontmake arg '{next_}'")
     return ""

From 31d7c7871796abdcaca25e98535abbcfe188b950 Mon Sep 17 00:00:00 2001
From: Colin Rofls <colin@cmyr.net>
Date: Thu, 31 Oct 2024 15:21:02 -0400
Subject: [PATCH 16/16] [fontc] Set --drop-implied-oncurves

---
 Lib/gftools/builder/fontc.py                     | 2 +-
 Lib/gftools/builder/operations/fontc/__init__.py | 3 +++
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/Lib/gftools/builder/fontc.py b/Lib/gftools/builder/fontc.py
index 9d951554f..5033248f8 100644
--- a/Lib/gftools/builder/fontc.py
+++ b/Lib/gftools/builder/fontc.py
@@ -54,7 +54,7 @@ def modify_config(self, config: dict):
             config["splitItalic"] = False
             # set --no-production-names, because it's easier to debug
             extra_args = config.get("extraFontmakeArgs") or ""
-            extra_args += " --no-production-names"
+            extra_args += " --no-production-names --drop-implied-oncurves"
             config["extraFontmakeArgs"] = extra_args
             # override config to turn not build instances if we're variable
             if self.will_build_variable_font(config):
diff --git a/Lib/gftools/builder/operations/fontc/__init__.py b/Lib/gftools/builder/operations/fontc/__init__.py
index e25cad2ae..e3f0fb6dd 100644
--- a/Lib/gftools/builder/operations/fontc/__init__.py
+++ b/Lib/gftools/builder/operations/fontc/__init__.py
@@ -53,6 +53,9 @@ def rewrite_one_arg(args: List[str]) -> str:
             next_ = f"{next_} {filter_}"
     elif next_ == "--no-production-names":
         return next_
+    elif next_ == "--drop-implied-oncurves":
+        # this is our default behaviour so no worries
+        return ""
     else:
         raise ValueError(f"unknown fontmake arg '{next_}'")
     return ""