Add tests for dynamically invoked break and continue

src/builtin.cpp

@@ -271,6 +271,7 @@ static maybe_t<int> builtin_break_continue(parser_t &parser, io_streams_t &strea
     }
 
     // Paranoia: ensure we have a real loop.
+    // This is checked in the AST but we may be invoked dynamically, e.g. just via "eval break".
     bool has_loop = false;
     for (const auto &b : parser.blocks()) {
         if (b.type() == block_type_t::while_block || b.type() == block_type_t::for_block) {

tests/checks/basic.fish

@@ -406,6 +406,34 @@ while contains $i a
 end
 #CHECK: Doop
 
+# break and continue may be dynamically invoked.
+set dyn_break break
+set dyn_continue continue
+
+while true
+    $dyn_break
+    echo "I should be unreachable"
+end
+
+for foo in 1 2 3
+    $dyn_continue
+    echo "I should be unreachable"
+end
+
+# Check that these error correctly.
+# Simplify __fish_print_help, as it's noisy.
+function __fish_print_help
+    echo $argv[2..]
+end
+$dyn_break
+eval break
+#CHECKERR: break: Not inside of loop
+#CHECKERR: break: Not inside of loop
+$dyn_continue
+eval continue
+#CHECKERR: continue: Not inside of loop
+#CHECKERR: continue: Not inside of loop
+
 # Test implicit cd. This should do nothing.
 ./