read: Actually only fire fish_read, not fish_prompt event

Fixes #8797.

src/builtins/read.cpp

@@ -224,6 +224,7 @@ static int read_interactive(parser_t &parser, wcstring &buff, int nchars, bool s
 
     conf.left_prompt_cmd = prompt;
     conf.right_prompt_cmd = right_prompt;
+    conf.event = L"fish_read";
 
     conf.in = in;
 
@@ -233,7 +234,6 @@ static int read_interactive(parser_t &parser, wcstring &buff, int nchars, bool s
     commandline_set_buffer(commandline, std::wcslen(commandline));
     scoped_push<bool> interactive{&parser.libdata().is_interactive, true};
 
-    event_fire_generic(parser, L"fish_read");
     auto mline = reader_readline(nchars);
     interactive.restore();
     if (mline) {

src/reader.cpp

@@ -2799,6 +2799,7 @@ static int read_i(parser_t &parser) {
     conf.syntax_check_ok = true;
     conf.autosuggest_ok = check_autosuggestion_enabled(parser.vars());
     conf.expand_abbrev_ok = true;
+    conf.event = L"fish_prompt";
 
     if (parser.is_breakpoint() && function_exists(DEBUG_PROMPT_FUNCTION_NAME, parser)) {
         conf.left_prompt_cmd = DEBUG_PROMPT_FUNCTION_NAME;
@@ -4009,7 +4010,9 @@ maybe_t<wcstring> reader_data_t::readline(int nchars_or_0) {
     }
     first_prompt = false;
 
-    event_fire_generic(parser(), L"fish_prompt");
+    if (!conf.event.empty()) {
+        event_fire_generic(parser(), conf.event.c_str());
+    }
     exec_prompt();
 
     /// A helper that kicks off syntax highlighting, autosuggestion computing, and repaints.

src/reader.h

@@ -196,6 +196,9 @@ struct reader_config_t {
     /// Right prompt command, typically fish_right_prompt.
     wcstring right_prompt_cmd{};
 
+    /// Name of the event to trigger once we're set up.
+    wcstring event{};
+
     /// Whether tab completion is OK.
     bool complete_ok{false};
 

tests/pexpects/read.py

@@ -144,3 +144,15 @@ expect_read_prompt()
 send("jkl\n")
 expect_str("ghi then jkl\r\n")
 expect_prompt()
+
+# Long line so we don't have to count prompts
+sendline("""set -g fish_prompt_fired 0; function dontfire --on-event fish_prompt; set -g fish_prompt_fired (math $fish_prompt_fired + 1); end; function dofire --on-event fish_read; set -g fish_read_fired 1; end""")
+
+expect_prompt()
+sendline("read foo")
+expect_read_prompt()
+sendline("text")
+expect_prompt()
+# Once for right after setting the listener, another for after the read.
+print_var_contents("fish_prompt_fired", "2")
+print_var_contents("fish_read_fired", "1")