Add package core:flags

core/flags/errors.odin

@@ -0,0 +1,58 @@
+package flags
+
+import "base:runtime"
+import "core:net"
+import "core:os"
+
+Parse_Error_Reason :: enum {
+	None,
+	// An extra positional argument was given, and there is no `varg` field.
+	Extra_Positional,
+	// The underlying type does not support the string value it is being set to.
+	Bad_Value,
+	// No flag was given by the user.
+	No_Flag,
+	// No value was given by the user.
+	No_Value,
+	// The flag on the struct is missing.
+	Missing_Flag,
+	// The type itself isn't supported.
+	Unsupported_Type,
+}
+
+Unified_Parse_Error_Reason :: union #shared_nil {
+	Parse_Error_Reason,
+	runtime.Allocator_Error,
+	net.Parse_Endpoint_Error,
+}
+
+// Raised during parsing, naturally.
+Parse_Error :: struct {
+	reason: Unified_Parse_Error_Reason,
+	message: string,
+}
+
+// Raised during parsing.
+// Provides more granular information than what just a string could hold.
+Open_File_Error :: struct {
+	filename: string,
+	errno: os.Errno,
+	mode: int,
+	perms: int,
+}
+
+// Raised during parsing.
+Help_Request :: distinct bool
+
+
+// Raised after parsing, during validation.
+Validation_Error :: struct {
+	message: string,
+}
+
+Error :: union {
+	Parse_Error,
+	Open_File_Error,
+	Help_Request,
+	Validation_Error,
+}