Update ab.

build/c.py

@@ -95,7 +95,9 @@ def cxxfile(
 def findsources(name, srcs, deps, cflags, toolchain, filerule, cwd):
     headers = filenamesmatchingof(srcs, "*.h")
     cflags = cflags + ["-I" + dirname(h) for h in headers]
-    deps = deps + headers
+
+    for d in deps:
+        headers += d.args.get("cheaders", [d])
 
     objs = []
     for s in flatten(srcs):
@@ -103,7 +105,7 @@ def findsources(name, srcs, deps, cflags, toolchain, filerule, cwd):
             filerule(
                 name=join(name, f.removeprefix("$(OBJ)/")),
                 srcs=[f],
-                deps=deps,
+                deps=headers,
                 cflags=cflags,
                 toolchain=toolchain,
                 cwd=cwd,
@@ -129,8 +131,16 @@ def cheaders(
     caller_cflags=[],
     deps: Targets = None,
 ):
+    hdr_deps = []
+    for d in deps:
+        hdr_deps += d.args.get("cheaders", [d])
+
+    hdr_caller_cflags = collectattrs(
+        targets=hdr_deps, name="caller_cflags", initial=caller_cflags
+    )
+
     cs = []
-    ins = list(hdrs.values())
+    ins = hdrs.values()
     outs = []
     i = 0
     for dest, src in hdrs.items():
@@ -139,7 +149,7 @@ def cheaders(
             len(s) == 1
         ), "the target of a header must return exactly one file"
 
-        cs += ["cp {ins[" + str(i) + "]} {outs[" + str(i) + "]}"]
+        cs += ["$(CP) {ins[" + str(i) + "]} {outs[" + str(i) + "]}"]
         outs += ["=" + dest]
         i = i + 1
 
@@ -148,9 +158,9 @@ def cheaders(
         ins=ins,
         outs=outs,
         commands=cs,
-        deps=deps,
+        deps=hdr_deps,
         label="CHEADERS",
-        args={"caller_cflags": caller_cflags + ["-I" + self.dir]},
+        args={"caller_cflags": hdr_caller_cflags + ["-I" + self.dir]},
     )
 
 
@@ -174,7 +184,7 @@ def libraryimpl(
         cheaders(
             replaces=self,
             hdrs=hdrs,
-            deps=targetswithtraitsof(deps, "cheaders"),
+            deps=deps,
             caller_cflags=caller_cflags,
         )
         return
@@ -182,7 +192,7 @@ def libraryimpl(
         hr = cheaders(
             name=self.localname + "_hdrs",
             hdrs=hdrs,
-            deps=targetswithtraitsof(deps, "cheaders"),
+            deps=deps,
             caller_cflags=caller_cflags,
         )
         hr.materialise()
@@ -191,7 +201,7 @@ def libraryimpl(
     objs = findsources(
         self.localname,
         srcs,
-        targetswithtraitsof(deps, "cheaders"),
+        deps,
         cflags,
         toolchain,
         kind,
@@ -205,13 +215,15 @@ def libraryimpl(
         label=label,
         commands=commands,
         args={
-            "caller_cflags": collectattrs(
-                targets=deps + ([hr] if hr else []), name="caller_cflags"
-            ),
             "caller_ldflags": collectattrs(
                 targets=deps, name="caller_ldflags", initial=caller_ldflags
             ),
-        },
+        }
+        | (
+            {"cheaders": [hr], "caller_cflags": hr.args["caller_cflags"]}
+            if hr
+            else {}
+        ),
         traits={"cheaders"},
     )
     self.outs = self.outs + (hr.outs if hr else [])