Make eval override previous status

Closes #5692 (again).

src/builtin_eval.cpp

@@ -9,6 +9,7 @@
 
 #include "builtin.h"
 #include "common.h"
+#include "exec.h"
 #include "fallback.h"  // IWYU pragma: keep
 #include "io.h"
 #include "parser.h"
@@ -16,8 +17,6 @@
 #include "wgetopt.h"
 #include "wutil.h"  // IWYU pragma: keep
 
-class parser_t;
-
 /// Implementation of eval builtin.
 int builtin_eval(parser_t &parser, io_streams_t &streams, wchar_t **argv) {
     int argc = builtin_count_args(argv);
@@ -28,16 +27,20 @@ int builtin_eval(parser_t &parser, io_streams_t &streams, wchar_t **argv) {
         new_cmd += argv[i];
     }
 
-    // debug(1, "new_cmd: %ls", new_cmd.c_str());
-
+    size_t cached_exec_count = exec_get_exec_count();
     int status = STATUS_CMD_OK;
     if (argc > 1) {
         if (parser.eval(std::move(new_cmd), *streams.io_chain, block_type_t::TOP) != 0) {
             // This indicates a parse error; nothing actually got executed.
             status = STATUS_CMD_ERROR;
+        } else if (cached_exec_count == exec_get_exec_count()) {
+            // Issue #5692, in particular, to catch `eval ""`, `eval "begin; end;"`, etc.
+            // where we have an argument but nothing is executed.
+            status = STATUS_CMD_OK;
         } else {
             status = proc_get_last_status();
         }
     }
+
     return status;
 }

src/exec.cpp

@@ -864,6 +864,14 @@ static bool exec_block_or_func_process(parser_t &parser, std::shared_ptr<job_t>
     return true;
 }
 
+// The number of overall "command" executions, for whatever definition of "command". Its delta
+// is used to determine the number of recursive `exec_process_in_job()` invocations.
+static size_t exec_count = 0;
+
+size_t exec_get_exec_count() {
+    return exec_count;
+}
+
 /// Executes a process \p in job \j, using the pipes \p pipes (which may have invalid fds if this is
 /// the first or last process).
 /// \p deferred_pipes represents the pipes from our deferred process; if set ensure they get closed
@@ -926,9 +934,6 @@ static bool exec_process_in_job(parser_t &parser, process_t *p, std::shared_ptr<
         }
     }
 
-    // The number of overall "command" executions, for whatever definition of "command". Its delta
-    // is used to determine the number of recursive `exec_process_in_job()` invocations.
-    static size_t exec_count = 0;
     if (p->type != process_type_t::block_node) {
         // An simple `begin ... end` should not be considered an execution of a command.
         exec_count++;

src/exec.h

@@ -31,6 +31,9 @@ int exec_subshell(const wcstring &cmd, parser_t &parser, bool preserve_exit_stat
 /// Loops over close until the syscall was run without being interrupted.
 void exec_close(int fd);
 
+/// Returns the number of executions. May roll over.
+size_t exec_get_exec_count();
+
 /// Gets the interpreter for a given command.
 char *get_interpreter(const char *command, char *interpreter, size_t buff_size);