Make build with the new ab --- but the tests fail.

build/ab.py

@@ -17,6 +17,9 @@ import inspect
 import string
 import sys
 import hashlib
+import re
+import ast
+from collections import namedtuple
 
 verbose = False
 quiet = False
@@ -26,6 +29,22 @@ unmaterialisedTargets = {}  # dict, not set, to get consistent ordering
 materialisingStack = []
 defaultGlobals = {}
 
+RE_FORMAT_SPEC = re.compile(
+    r"(?:(?P<fill>[\s\S])?(?P<align>[<>=^]))?"
+    r"(?P<sign>[- +])?"
+    r"(?P<pos_zero>z)?"
+    r"(?P<alt>#)?"
+    r"(?P<zero_padding>0)?"
+    r"(?P<width_str>\d+)?"
+    r"(?P<grouping>[_,])?"
+    r"(?:(?P<decimal>\.)(?P<precision_str>\d+))?"
+    r"(?P<type>[bcdeEfFgGnosxX%])?"
+)
+
+CommandFormatSpec = namedtuple(
+    "CommandFormatSpec", RE_FORMAT_SPEC.groupindex.keys()
+)
+
 sys.path += ["."]
 old_import = builtins.__import__
 
@@ -80,6 +99,29 @@ def error(message):
     raise ABException(message)
 
 
+class BracketedFormatter(string.Formatter):
+    def parse(self, format_string):
+        while format_string:
+            left, *right = format_string.split("$[", 1)
+            if not right:
+                yield (left, None, None, None)
+                break
+            right = right[0]
+
+            offset = len(right) + 1
+            try:
+                ast.parse(right)
+            except SyntaxError as e:
+                if not str(e).startswith("unmatched ']'"):
+                    raise e
+                offset = e.offset
+
+            expr = right[0 : offset - 1]
+            format_string = right[offset:]
+
+            yield (left if left else None, expr, None, None)
+
+
 def Rule(func):
     sig = inspect.signature(func)
 
@@ -115,7 +157,7 @@ def Rule(func):
         t.callback = func
         t.traits.add(func.__name__)
         if "args" in kwargs:
-            t.args |= kwargs["args"]
+            t.args.update(kwargs["args"])
             del kwargs["args"]
         if "traits" in kwargs:
             t.traits |= kwargs["traits"]
@@ -166,7 +208,7 @@ class Target:
         return f"Target('{self.name}')"
 
     def templateexpand(selfi, s):
-        class Formatter(string.Formatter):
+        class Formatter(BracketedFormatter):
             def get_field(self, name, a1, a2):
                 return (
                     eval(name, selfi.callback.__globals__, selfi.args),
@@ -355,8 +397,16 @@ class TargetsMap:
         return output
 
 
+def _removesuffix(self, suffix):
+    # suffix='' should not call self[:-0].
+    if suffix and self.endswith(suffix):
+        return self[: -len(suffix)]
+    else:
+        return self[:]
+
+
 def loadbuildfile(filename):
-    filename = filename.replace("/", ".").removesuffix(".py")
+    filename = _removesuffix(filename.replace("/", "."), ".py")
     builtins.__import__(filename)
 
 
@@ -406,8 +456,9 @@ def emit(*args, into=None):
         outputFp.write(s)
 
 
-def emit_rule(name, ins, outs, cmds=[], label=None):
-    fins = filenamesof(ins)
+def emit_rule(self, ins, outs, cmds=[], label=None):
+    name = self.name
+    fins = set(filenamesof(ins))
     fouts = filenamesof(outs)
     nonobjs = [f for f in fouts if not f.startswith("$(OBJ)")]
 
@@ -433,8 +484,23 @@ def emit_rule(name, ins, outs, cmds=[], label=None):
 
         if label:
             emit("\t$(hide)", "$(ECHO) $(PROGRESSINFO)", label, into=lines)
+
+        sandbox = join(self.dir, "sandbox")
+        emit("\t$(hide)", f"rm -rf {sandbox}", into=lines)
+        emit(
+            "\t$(hide)",
+            f"$(PYTHON) build/_sandbox.py --link -s {sandbox}",
+            *fins,
+            into=lines,
+        )
         for c in cmds:
-            emit("\t$(hide)", c, into=lines)
+            emit(f"\t$(hide) cd {sandbox} && (", c, ")", into=lines)
+        emit(
+            "\t$(hide)",
+            f"$(PYTHON) build/_sandbox.py --export -s {sandbox}",
+            *fouts,
+            into=lines,
+        )
     else:
         assert len(cmds) == 0, "rules with no outputs cannot have commands"
         emit(name, ":", *fins, into=lines)
@@ -479,10 +545,10 @@ def simplerule(
         cs += [self.templateexpand(c)]
 
     emit_rule(
-        name=self.name,
+        self=self,
         ins=ins + deps,
         outs=outs,
-        label=self.templateexpand("{label} {name}") if label else None,
+        label=self.templateexpand("$[label] $[name]") if label else None,
         cmds=cs,
     )
 
@@ -507,7 +573,7 @@ def export(self, name=None, items: TargetsMap = {}, deps: Targets = []):
             cwd=self.cwd,
             ins=[srcs[0]],
             outs=[destf],
-            commands=["$(CP) %s %s" % (srcs[0], destf)],
+            commands=["$(CP) -H %s %s" % (srcs[0], destf)],
             label="",
         )
         subrule.materialise()
@@ -516,7 +582,7 @@ def export(self, name=None, items: TargetsMap = {}, deps: Targets = []):
         replaces=self,
         ins=outs + deps,
         outs=["=sentinel"],
-        commands=["touch {outs[0]}"],
+        commands=["touch $[outs[0]]"],
         label="EXPORT",
     )