feat: infer complete ptrcast target types

std/io/file.hon

@@ -98,7 +98,7 @@ writer func(file File) Writer {
 		.read_write: flags = c.O_RDWR
 	}
 	while true {
-		fd c_int :: c.open(ptrcast!(c_char, path.ptr), flags)
+		fd c_int :: c.open(ptrcast!(path.ptr), flags)
 		if fd >= 0 {
 			return Handle {file_desc = fd}
 		}

std/io/io.hon

@@ -317,7 +317,7 @@ print func(output Writer, $format []u8, $Args type, args Args) void ! WriteError
 	}
 }
 @hide distinct_value func($Backing, $Distinct type, value Distinct) Backing {
-	return ptrcast!(Backing, &value)^
+	return ptrcast!(@Backing, &value)^
 }
 
 @hide scalar_or_distinct_type func($T type) bool {
@@ -357,14 +357,14 @@ print func(output Writer, $format []u8, $Args type, args Args) void ! WriteError
 			count c_int := 0
 			if sizeof!(T) == 4 {
 				if scientific {
-					count = c.snprintf(ptrcast!(c_char, (&buffer).ptr), c_ulong(buffer.len), "%.8e", value)
+					count = c.snprintf(ptrcast!((&buffer).ptr), c_ulong(buffer.len), "%.8e", value)
 				} else {
-					count = c.snprintf(ptrcast!(c_char, (&buffer).ptr), c_ulong(buffer.len), "%.9g", value)
+					count = c.snprintf(ptrcast!((&buffer).ptr), c_ulong(buffer.len), "%.9g", value)
 				}
 			} else if scientific {
-				count = c.snprintf(ptrcast!(c_char, (&buffer).ptr), c_ulong(buffer.len), "%.16e", value)
+				count = c.snprintf(ptrcast!((&buffer).ptr), c_ulong(buffer.len), "%.16e", value)
 			} else {
-				count = c.snprintf(ptrcast!(c_char, (&buffer).ptr), c_ulong(buffer.len), "%.17g", value)
+				count = c.snprintf(ptrcast!((&buffer).ptr), c_ulong(buffer.len), "%.17g", value)
 			}
 			if count < 0 or usize(count) >= buffer.len {
 				return .write_failed

std/mem/mem.hon

@@ -48,7 +48,7 @@ alloc func($T type, allocator Allocator, count usize) []mut T ! AllocError {
 
 	memory ?*mut u8 := raw_alloc(allocator, count * element_size, alignof!(T))
 	if memory |bytes| {
-		pointer *mut T :: ptrcast!(T, bytes)
+		pointer *mut T :: ptrcast!(bytes)
 		return pointer[..count]
 	}
 	return .out_of_memory
@@ -78,7 +78,7 @@ realloc func($T type, allocator Allocator, memory []mut T, new_count usize) []mu
 	old_memory ?*mut u8 := null
 	old_size usize := 0
 	if memory.len != 0 {
-		old_memory = ptrcast!(u8, memory.ptr)
+		old_memory = ptrcast!(memory.ptr)
 		old_size = memory.len * element_size
 	}
 	resized ?*mut u8 := raw_realloc(
@@ -89,7 +89,7 @@ realloc func($T type, allocator Allocator, memory []mut T, new_count usize) []mu
 		alignof!(T),
 	)
 	if resized |bytes| {
-		pointer *mut T :: ptrcast!(T, bytes)
+		pointer *mut T :: ptrcast!(bytes)
 		return pointer[..new_count]
 	}
 
@@ -101,7 +101,6 @@ realloc func($T type, allocator Allocator, memory []mut T, new_count usize) []mu
 free func($T type, allocator Allocator, memory []T) void {
 	if (memory.len == 0 or sizeof!(T) == 0) return
 	raw_free(allocator, ptrcast!(
-		u8,
 		constcast!(memory).ptr),
 		memory.len * sizeof!(T),
 		alignof!(T),
@@ -110,7 +109,7 @@ free func($T type, allocator Allocator, memory []T) void {
 
 #! get an empty slice of type `T` with `count` elements.
 empty_slice func($T type, count usize) []mut T {
-	pointer *mut T :: ptrcast!(T, (&empty_storage).ptr)
+	pointer *mut T :: ptrcast!((&empty_storage).ptr)
 	return pointer[..count]
 }
 
@@ -138,14 +137,14 @@ empty func($T type) []mut T {
 	if (power_of_two(alignment) == false) return null
 
 	if alignment <= malloc_alignment {
-		return ptrcast!(u8, c.malloc(c_ulong(size)))
+		return ptrcast!(c.malloc(c_ulong(size)))
 	}
 
 	memory [1]mut ?*mut anyopaque := [null]
 	status c_int := c.posix_memalign((&memory).ptr, c_ulong(alignment), c_ulong(size))
 	if (status != 0) return null
 
-	return ptrcast!(u8, memory[0])
+	return ptrcast!(memory[0])
 }
 
 @hide c_realloc func(_ ?@mut anyopaque, memory ?*mut u8, old_size usize, new_size usize, alignment usize) ?*mut u8 {
@@ -158,7 +157,7 @@ empty func($T type) []mut T {
 
 	if memory |old_memory| {
 		if alignment <= malloc_alignment {
-			return ptrcast!(u8, c.realloc(old_memory, c_ulong(new_size)))
+			return ptrcast!(c.realloc(old_memory, c_ulong(new_size)))
 		}
 
 		new_memory ?*mut u8 := c_alloc(null, new_size, alignment)