From 3f5c60e6349094ab77636ea12e0d7cc4c5dd0f9a Mon Sep 17 00:00:00 2001
From: Fabian Homborg <FHomborg@gmail.com>
Date: Mon, 17 Feb 2020 11:12:01 +0100
Subject: [PATCH] Silence some errors for `fish --no-execute`

It used to error out when a command wasn't known, even when it was a
function that would only be discovered via autoloading.

Now we just accept that a command doesn't exist when no-execute is
given - we're not gonna execute it anyway.

Also, in the same breath stop counting empty commands after expansion
and empty wildcard expansions as errors - these depend on runtime
values, so we can't verify them without executing.

Fixes #977.

(note that it still executes "time", but that's another commit)
---
 src/parse_execution.cpp      | 10 ++++++++--
 tests/checks/no-execute.fish | 22 ++++++++++++++++++++++
 2 files changed, 30 insertions(+), 2 deletions(-)
 create mode 100644 tests/checks/no-execute.fish

diff --git a/src/parse_execution.cpp b/src/parse_execution.cpp
index fe7c6a33a..e524af8c6 100644
--- a/src/parse_execution.cpp
+++ b/src/parse_execution.cpp
@@ -718,7 +718,8 @@ end_execution_reason_t parse_execution_context_t::expand_command(
     assert(expand_err == expand_result_t::ok);
 
     // Complain if the resulting expansion was empty, or expanded to an empty string.
-    if (out_cmd->empty()) {
+    // For no-exec it's okay, as we can't really perform the expansion.
+    if (out_cmd->empty() && !no_exec()) {
         return this->report_error(STATUS_ILLEGAL_CMD, statement,
                                   _(L"The expanded command was empty."));
     }
@@ -741,6 +742,8 @@ end_execution_reason_t parse_execution_context_t::populate_plain_process(
     if (ret != end_execution_reason_t::ok) {
         return ret;
     }
+    // For no-exec, having an empty command is okay. We can't do anything more with it tho.
+    if (no_exec()) return end_execution_reason_t::ok;
     assert(!cmd.empty() && "expand_command should not produce an empty command");
 
     // Determine the process type.
@@ -795,7 +798,8 @@ end_execution_reason_t parse_execution_context_t::populate_plain_process(
         }
 
         if (!has_command && !use_implicit_cd) {
-            // No command.
+            // No command. If we're --no-execute return okay - it might be a function.
+            if (no_exec()) return end_execution_reason_t::ok;
             return this->handle_command_not_found(cmd, statement, no_cmd_err_code);
         }
     }
@@ -875,6 +879,8 @@ end_execution_reason_t parse_execution_context_t::expand_arguments_from_nodes(
             }
             case expand_result_t::wildcard_no_match: {
                 if (glob_behavior == failglob) {
+                    // For no_exec, ignore the error - this might work at runtime.
+                    if (no_exec()) return end_execution_reason_t::ok;
                     // Report the unmatched wildcard error and stop processing.
                     return report_error(STATUS_UNMATCHED_WILDCARD, arg_node, WILDCARD_ERR_MSG,
                                         get_source(arg_node).c_str());
diff --git a/tests/checks/no-execute.fish b/tests/checks/no-execute.fish
new file mode 100644
index 000000000..1ea4f8aba
--- /dev/null
+++ b/tests/checks/no-execute.fish
@@ -0,0 +1,22 @@
+#RUN: %fish -C 'set -l fish %fish' %s
+
+# Test that fish -n doesn't check for command existence - function autoloading throws a wrench in that.
+echo "type foo" | $fish -n
+echo $status
+#CHECK: 0
+
+# Test that it doesn't check globs.
+echo "echo /asfjidhfiusnlkxcnvklxcvlkmcxlv*" | $fish -n
+echo $status
+#CHECK: 0
+
+# Test that it does print syntax errors.
+echo "begin; echo oops" | $fish -n
+#CHECKERR: fish: Missing end to balance this begin
+#CHECKERR: begin; echo oops
+#CHECKERR: ^
+echo $status
+#CHECK: 127
+
+# Littlecheck assumes a status of 127 means the shebang was invalid.
+exit 0