function pointers and callbacks

LANGUAGE.md

@@ -24,7 +24,9 @@
 - information-preserving and information-forgetting pointer-to-array decay and sentinel slice/pointer weakening; array values never implicitly decay
 - narrow immutable zero-terminated byte pointer conversion to `*c_char` and `[*;0]c_char`, without general `u8`/`c_char` interchange
 - optionals with trapping postfix `?`, `orelse`, and nullable pointer representation
-- source-order native structs, keyed literals, and defined or opaque pointer-only `c_struct`
+- source-order native structs, defined or opaque `c_struct`, and keyed record literals
+- complete plain imported C structs and unions as runtime values; incomplete or unsupported-layout records remain pointer-only
+- C function pointer types as pointer-sized runtime values, including manual `*c_func(...) T` spelling and nullable imported callback typedefs
 - postfix pointer dereference, general writable locations, function calls, assignments, and returns
 
 ### functions and packages
@@ -33,12 +35,13 @@
 - bodyful `c_func` definitions using the c calling convention
 - bodyless `c_func` declarations with exact, globally unique external symbol names
 - concrete-only foreign signatures
-- Apple Silicon C ABI scalar and pointer lowering, including narrow integer extension attributes
+- Apple Silicon C ABI scalar, pointer, and fixed-signature plain record/union lowering, including narrow integer extension attributes
 - directory packages with merged declarations
 - file-local relative imports, aliases, and qualified member access
 - relative `.h` imports as synthetic package namespaces
-- transitive external C function prototypes, typedef chains, C scalars, and pointers to opaque C records
+- transitive external C function prototypes, typedef chains, C scalars, fixed arrays, complete plain records/unions, and pointers to opaque C records
 - bodyless manual and imported C variadic declarations with target-aware default argument promotions
+- passing concrete `c_func` declarations/definitions as C callback values and calling non-null C function pointers with postfix call syntax
 - reference-time diagnostics for unsupported imported C declarations
 
 ### compiler behavior
@@ -60,9 +63,9 @@
 ### scalar and compound types
 
 - tuples and native variadic functions
-- C unions, C enums, and by-value C record ABI lowering
+- C enums and non-plain C record layouts
 
 ### advanced c imports
 
-- C enums, external variables, function pointers, callbacks, macros, and static inline functions
-- target-specific by-value C record and union ABI lowering
+- C enums, external variables, macros, and static inline functions
+- additional target-specific C ABI lowering