Allow -X at later positions in the CLI

In particular, we now allow `-X` to _not_ be the first cli argument.
This makes way for common options such as `--web-bundle` to be specified
_before_ the `-X` flag.

Author: bryango

src/bin/tectonic/main.rs

@@ -6,7 +6,6 @@ use std::{env, process, str::FromStr};
 use structopt::StructOpt;
 use tectonic_status_base::plain::PlainStatusBackend;
 
-use structopt::clap;
 use tectonic::{
     config::PersistentConfig,
     errors::SyncError,
@@ -40,15 +39,15 @@ mod v2cli {
 #[derive(Debug, StructOpt)]
 #[structopt(name = "Tectonic", about = "Process a (La)TeX document")]
 struct CliOptions {
-    /// Use experimental V2 interface (see `tectonic -X --help`); must be the first argument
+    /// Use experimental V2 interface (see `tectonic -X --help`)
     #[structopt(short = "X")]
     use_v2: bool,
 
     /// How much chatter to print when running
     #[structopt(long = "chatter", short, name = "level", default_value = "default", possible_values(&["default", "minimal"]))]
     chatter_level: String,
 
-    /// Enable/disable colorful log output.
+    /// Enable/disable colorful log output
     #[structopt(long = "color", name = "when", default_value = "auto", possible_values(&["always", "auto", "never"]))]
     cli_color: String,
 
@@ -78,26 +77,34 @@ fn main() {
         unstable_opts::UnstableOptions::from_unstable_args(args.unstable.into_iter());
     }
 
-    // Migration to the "cargo-style" command-line interface. If the first
-    // argument is `-X`, or argv[0] contains `nextonic`, we activate the
+    // Migration to the "cargo-style" command-line interface. If the arguments
+    // list contains `-X`, or argv[0] contains `nextonic`, we activate the
     // alternative operation mode. Once this experimental mode is working OK,
     // we'll start printing a message telling people to prefer the `-X` option
     // and use `-X compile` for the "classic" ("rustc"-style, current)
     // interface. After that's been in place for a while, we'll make V2 mode the
     // default.
 
     let mut v2cli_enabled = false;
-    let mut v2cli_arg_idx = 1;
+    let mut v2cli_args = os_args[1..].to_vec(); // deep copy
 
     if !os_args.is_empty() && os_args[0].to_str().map(|s| s.contains("nextonic")) == Some(true) {
         v2cli_enabled = true;
-    } else if os_args.len() > 1 && os_args[1] == "-X" {
-        v2cli_enabled = true;
-        v2cli_arg_idx = 2;
+    } else if let Some(index) = v2cli_args
+        .to_vec()
+        .iter()
+        .position(|s| s.to_str().unwrap_or_default() == "-X")
+    {
+        // Try to parse as v1 cli first, and when that doesn't work,
+        // interpret it as v2 cli:
+        if CliOptions::from_args_safe().is_err() || CliOptions::from_args().use_v2 {
+            v2cli_enabled = true;
+            v2cli_args.remove(index);
+        }
     }
 
     if v2cli_enabled {
-        v2cli::v2_main(&os_args[v2cli_arg_idx..]);
+        v2cli::v2_main(&v2cli_args);
         return;
     }
 
@@ -154,15 +161,6 @@ fn main() {
         Box::new(PlainStatusBackend::new(chatter_level)) as Box<dyn StatusBackend>
     };
 
-    if args.use_v2 {
-        let err = clap::Error::with_description(
-            "-X option must be the first argument if given",
-            clap::ErrorKind::ArgumentConflict,
-        );
-        status.report_error(&err.into());
-        process::exit(1)
-    }
-
     // Now that we've got colorized output, pass off to the inner function ...
     // all so that we can print out the word "error:" in red. This code
     // parallels various bits of the `error_chain` crate.

tests/executable.rs

@@ -957,21 +957,6 @@ fn extra_search_paths() {
     error_or_panic(&output);
 }
 
-/// -X in non-initial position fails
-#[test]
-fn bad_v2_position() {
-    let output = run_tectonic(&PathBuf::from("."), &["-", "-X"]);
-    error_or_panic(&output);
-}
-
-#[cfg(feature = "serialization")]
-#[test]
-fn bad_v2_position_build() {
-    let (_tempdir, temppath) = setup_v2();
-    let output = run_tectonic(&temppath, &["build", "-X"]);
-    error_or_panic(&output);
-}
-
 /// Ensures that watch command succeeds, and when a file is changed while running it rebuilds
 /// periodically
 #[cfg(all(feature = "serialization", not(target_arch = "mips")))]