fix(bash): use `eval` instead of a procsub for the POSIX mode (#5020)

fix(bash): use eval instead of a procsub for the POSIX mode

src/init/mod.rs

@@ -9,11 +9,11 @@ use which::which;
 shell. This command evaluates a more complicated script using `source` and
 process substitution.
 
-Directly using `eval` on a shell script causes it to be evaluated in
+Directly using `eval` on a shell script without proper quoting causes it to be
-a single line, which sucks because things like comments will comment out the
+evaluated in a single line, which sucks because things like comments will
-rest of the script, and you have to spam semicolons everywhere. By using
+comment out the rest of the script, and you have to spam semicolons
-source and process substitutions, we make it possible to comment and debug
+everywhere. By using source and process substitutions, we make it possible to
-the init scripts.
+comment and debug the init scripts.
 
 In the future, this may be changed to just directly evaluating the initscript
 using whatever mechanism is available in the host shell--this two-phase solution
@@ -106,8 +106,13 @@ pub fn init_stub(shell_name: &str) -> io::Result<()> {
 
     match shell_basename {
         "bash" => print!(
-            /*
+            /* We now use the following bootstrap:
-             * The standard bash bootstrap is:
+             *      `eval -- "$(starship init bash --print-full-init)"`
+             * which works in any version of Bash from 3.2 to the latest
+             * version and also works in the POSIX mode.
+             *
+             * ----
+             * Historically, the standard bash bootstrap was:
              *      `source <(starship init bash --print-full-init)`
              *
              * Unfortunately there is an issue with bash 3.2 (the MacOS
@@ -129,28 +134,25 @@ pub fn init_stub(shell_name: &str) -> io::Result<()> {
              * with the standard bootstrap, whereas bash 4.1 appears to be
              * consistently compatible.
              *
-             * The upshot of all of this, is that we will use the standard
+             * We had been using the standard bootstrap whenever the bash
-             * bootstrap whenever the bash version is 4.1 or higher. Otherwise,
+             * version is 4.1 or higher. Otherwise, we fell back to the
-             * we fall back to the `/dev/stdin` solution.
+             * `/dev/stdin` solution.
+             *
+             * However, process substitutions <(...) are not supported in the
+             * POSIX mode of Bash <= 5.0, so we switch to the approach with
+             * `eval -- "$(...)"`.  The reason for not using `eval` seems to be
+             * explained at the top of this file, i.e., the script will be
+             * evaluated as if it is a single line, but that is caused by an
+             * improper quoting.
              *
              * More background can be found in these pull requests:
              * https://github.com/starship/starship/pull/241
              * https://github.com/starship/starship/pull/278
+             * https://github.com/starship/starship/issues/1674
+             * https://github.com/starship/starship/pull/5020
+             * https://github.com/starship/starship/issues/5382
              */
-            r#"
+            r#"eval -- "$({0} init bash --print-full-init)""#,
-            __main() {{
-                local major="${{BASH_VERSINFO[0]}}"
-                local minor="${{BASH_VERSINFO[1]}}"
-
-                if ((major > 4)) || {{ ((major == 4)) && ((minor >= 1)); }}; then
-                    source <({0} init bash --print-full-init)
-                else
-                    source /dev/stdin <<<"$({0} init bash --print-full-init)"
-                fi
-            }}
-            __main
-            unset -f __main
-            "#,
             starship.sprint_posix()?
         ),
         "zsh" => print_script(ZSH_INIT, &starship.sprint_posix()?),