fix: assorted completion issues with ~ and vars (#199)

* Propagate exit results from failed command substitution through to assignments that depend on it.
* Targeted compatibility fix for limited set of printf %q cases
* Return 1 from compgen when no completions were generated
* Only filtering completions based on the token-being-completed for action-generated completions, not for those coming from an invoked function
* Stop unconditionally expanding token-being-completed in non-compgen scenarios.

.config/nextest.toml

@@ -2,6 +2,7 @@
 retries = 3
 status-level = "slow"
 slow-timeout = { period = "5s", terminate-after = 3, grace-period = "2s" }
+fail-fast = false
 
 [profile.default.junit]
 path = "test-results.xml"

brush-core/src/builtins/complete.rs

@@ -442,7 +442,6 @@ impl builtins::Command for CompGenCommand {
         context: commands::ExecutionContext<'_>,
     ) -> Result<crate::builtins::ExitCode, crate::error::Error> {
         let spec = self.common_args.create_spec();
-
         let token_to_complete = self.word.as_deref().unwrap_or_default();
 
         // N.B. We basic-expand the token-to-be-completed first.
@@ -471,6 +470,12 @@ impl builtins::Command for CompGenCommand {
 
         match result {
             completion::Answer::Candidates(candidates, _options) => {
+                // We are expected to return 1 if there are no candidates, even if no errors
+                // occurred along the way.
+                if candidates.is_empty() {
+                    return Ok(builtins::ExitCode::Custom(1));
+                }
+
                 for candidate in candidates {
                     writeln!(context.stdout(), "{candidate}")?;
                 }

brush-core/src/builtins/echo.rs

@@ -55,7 +55,7 @@ impl builtins::Command for EchoCommand {
 
                 let (expanded_arg, keep_going) = escape::expand_backslash_escapes(
                     arg.as_str(),
-                    escape::EscapeMode::EchoBuiltin,
+                    escape::EscapeExpansionMode::EchoBuiltin,
                 )?;
                 s.push_str(&String::from_utf8_lossy(expanded_arg.as_slice()));
 

brush-core/src/builtins/printf.rs

@@ -1,7 +1,7 @@
 use clap::Parser;
 use std::io::Write;
 
-use crate::{builtins, commands, expansion};
+use crate::{builtins, commands, escape, expansion};
 
 /// Format a string.
 #[derive(Parser)]
@@ -40,13 +40,30 @@ impl PrintfCommand {
         &self,
         context: &commands::ExecutionContext<'_>,
     ) -> Result<String, crate::error::Error> {
-        // Special-case common format string: "%s".
         match self.format_and_args.as_slice() {
+            // Special-case common format string: "%s".
             [fmt, arg] if fmt == "%s" => Ok(arg.clone()),
+            // Special-case invocation of printf with %q-based format string from bash-completion.
+            // It has hard-coded expectation of backslash-style escaping instead of quoting.
+            [fmt, arg] if fmt == "%q" || fmt == "~%q" => {
+                Ok(Self::evaluate_format_with_percent_q(None, arg))
+            }
+            [fmt, arg] if fmt == "~%q" => Ok(Self::evaluate_format_with_percent_q(Some("~"), arg)),
+            // Fallback to external command.
             _ => self.evaluate_via_external_command(context),
         }
     }
 
+    fn evaluate_format_with_percent_q(prefix: Option<&str>, arg: &str) -> String {
+        let mut result = escape::quote_if_needed(arg, escape::QuoteMode::BackslashEscape);
+
+        if let Some(prefix) = prefix {
+            result.insert_str(0, prefix);
+        }
+
+        result
+    }
+
     #[allow(clippy::unwrap_in_result)]
     fn evaluate_via_external_command(
         &self,

brush-core/src/commands.rs

@@ -8,7 +8,7 @@ use command_fds::{CommandFdExt, FdMapping};
 use itertools::Itertools;
 
 use crate::{
-    builtins, error,
+    builtins, error, escape,
     interp::{self, Execute, ProcessGroupPolicy},
     openfiles::{self, OpenFile, OpenFiles},
     processes, sys, trace_categories, ExecutionParameters, ExecutionResult, Shell,
@@ -177,6 +177,24 @@ impl From<&String> for CommandArg {
     }
 }
 
+impl CommandArg {
+    pub fn quote_for_tracing(&self) -> String {
+        match self {
+            CommandArg::String(s) => escape::quote_if_needed(s, escape::QuoteMode::Quote),
+            CommandArg::Assignment(a) => {
+                let mut s = a.name.to_string();
+                let op = if a.append { "+=" } else { "=" };
+                s.push_str(op);
+                s.push_str(&escape::quote_if_needed(
+                    a.value.to_string().as_str(),
+                    escape::QuoteMode::Quote,
+                ));
+                s
+            }
+        }
+    }
+}
+
 #[allow(unused_variables)]
 pub(crate) fn compose_std_command<S: AsRef<OsStr>>(
     shell: &mut Shell,