Fix lints/errors when compiling specific feature combos

- Building with sqlite3 non-bundled may result in compile-time error if
  the system version is not new enough; the bindgen feature must be
  enabled to create ffi bindings from the system version.
- Some unused code warnings show up if some features are disabled,
  refactor code to make them go away.
- Update libloading to 0.8 to prevent dual dependencies in
  Cargo.lock (rusqlite's bundled feature requires it)

Signed-off-by: Manos Pitsidianakis <manos@pitsidianak.is>

Cargo.lock

@@ -1182,12 +1182,12 @@ dependencies = [
 
 [[package]]
 name = "libloading"
-version = "0.7.4"
+version = "0.8.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b67380fd3b2fbe7527a606e18729d21c6f3951633d0500574c4dc22d2d638b9f"
+checksum = "e310b3a6b5907f99202fcdb4960ff45b93735d7c7d96b760fcff8db2dc0e103d"
 dependencies = [
  "cfg-if",
- "winapi",
+ "windows-targets 0.48.5",
 ]
 
 [[package]]

meli/src/accounts/backend_ops.rs

@@ -53,8 +53,9 @@ impl Account {
         Ok(job_id)
     }
 
-    #[cfg(not(feature = "sqlite3"))]
-    pub(super) fn update_cached_env(&mut self, _: Envelope, _: Option<EnvelopeHash>) {}
+    //     #[cfg(not(feature = "sqlite3"))]
+    //     pub(super) fn update_cached_env(&mut self, _: Envelope, _:
+    // Option<EnvelopeHash>) {}
 
     #[cfg(feature = "sqlite3")]
     pub(super) fn update_cached_env(&mut self, env: Envelope, old_hash: Option<EnvelopeHash>) {

meli/src/mail/view/filters.rs

@@ -386,6 +386,7 @@ impl ViewFilter {
         {
             #[cfg(not(feature = "gpgme"))]
             {
+                _ = parts;
                 return Ok(Self {
                     filter_invocation: String::new(),
                     content_type: att.content_type.clone(),

meli/src/subcommands.rs

@@ -19,17 +19,19 @@
  * along with meli. If not, see <http://www.gnu.org/licenses/>.
  */
 
-#[cfg(feature = "cli-docs")]
-use std::io::prelude::*;
 use std::{
+    io::prelude::*,
     path::PathBuf,
     process::{Command, Stdio},
 };
 
 use crossbeam::channel::{Receiver, Sender};
-use melib::{Result, ShellExpandTrait};
+use melib::{utils::futures::timeout, Result, ShellExpandTrait};
 
-use crate::{args::PathOrStdio, *};
+use crate::{
+    args::{PathOrStdio, ToolOpt},
+    *,
+};
 
 pub fn create_config(path: Option<PathOrStdio>) -> Result<()> {
     let config_path = match path {
@@ -175,11 +177,7 @@ pub fn view(
     Ok(state)
 }
 
-pub fn tool(path: Option<PathBuf>, opt: args::ToolOpt) -> Result<()> {
-    use melib::utils::futures::timeout;
-
-    use crate::{args::ToolOpt, conf::composing::SendMail};
-
+pub fn tool(path: Option<PathBuf>, opt: ToolOpt) -> Result<()> {
     let config_path = if let Some(path) = path {
         path.expand()
     } else {
@@ -208,6 +206,8 @@ pub fn tool(path: Option<PathBuf>, opt: args::ToolOpt) -> Result<()> {
     match opt {
         #[cfg(feature = "smtp")]
         ToolOpt::SmtpShell { .. } => {
+            use crate::conf::composing::SendMail;
+
             let send_mail = file_account_conf
                 .conf_override
                 .composing

melib/Cargo.toml

@@ -34,7 +34,7 @@ indexmap = { version = "^1.5", default-features = false, features = ["serde-1"]
 isahc = { version = "^1.7.2", optional = true, default-features = false, features = ["http2", "json", "text-decoding"] }
 libc = { version = "0.2.125", features = ["extra_traits"] }
 
-libloading = "^0.7"
+libloading = "^0.8"
 log = { version = "0.4", features = ["std"] }
 native-tls = { version = "0.2.3", default-features = false, optional = true }
 nix = { version = "0.27", default-features = false, features = ["fs", "socket", "dir", "hostname"] }
@@ -73,8 +73,8 @@ mbox = ["notify"]
 notmuch = ["notify"]
 smtp = ["tls", "base64"]
 smtp-trace = ["smtp"]
-sqlite3 = ["rusqlite"]
-sqlite3-static = ["sqlite3", "rusqlite/bundled-full"]
+sqlite3 = ["sqlite3-static"]
+sqlite3-static = ["rusqlite", "rusqlite/bundled-full"]
 tls = ["native-tls"]
 tls-static = ["tls", "native-tls/vendored"]
 vcard = []