3724 - flag duplicate scenarios

I took this feature out in 3161 (back in Aug) to support scenarios in
lesson/recipes.mu. Setting up snapshots for scenario data structures
gives us the best of both worlds.

1 files changed, 23 insertions, 2 deletions

diff --git a/050scenario.cc b/050scenario.cc
index 5e4e9309..c1eeecf2 100644
--- a/050scenario.cc
+++ b/050scenario.cc
@@ -64,7 +64,14 @@ struct scenario {
 };
 
 :(before "End Globals")
-vector<scenario> Scenarios;
+vector<scenario> Scenarios, Scenarios_snapshot;
+set<string> Scenario_names, Scenario_names_snapshot;
+:(before "End save_snapshots")
+Scenarios_snapshot = Scenarios;
+Scenario_names_snapshot = Scenario_names;
+:(before "End restore_snapshots")
+Scenarios = Scenarios_snapshot;
+Scenario_names = Scenario_names_snapshot;
 
 //:: Parse the 'scenario' form.
 //: Simply store the text of the scenario.
@@ -84,6 +91,9 @@ else if (command == "pending-scenario") {
 scenario parse_scenario(istream& in) {
   scenario result;
   result.name = next_word(in);
+  if (contains_key(Scenario_names, result.name))
+    raise << "duplicate scenario name: '" << result.name << "'\n" << end();
+  Scenario_names.insert(result.name);
   if (result.name.empty()) {
     assert(!has_data(in));
     raise << "incomplete scenario at end of file\n" << end();
@@ -126,6 +136,17 @@ scenario foo [
 ]
 +run: {1: ("address" "array" "character")} <- new {"# not a comment": "literal-string"}
 
+:(scenarios run)
+:(scenario duplicate_scenarios)
+% Hide_errors = true;
+scenario foo [
+  1:num <- copy 0
+]
+scenario foo [
+  2:num <- copy 0
+]
++error: duplicate scenario name: 'foo'
+
 //:: Run scenarios when we run './mu test'.
 //: Treat the text of the scenario as a regular series of instructions.
 
@@ -269,7 +290,6 @@ void test_maybe_make_raw() {
 
 //: Watch out for redefinitions of scenario routines. We should never ever be
 //: doing that, regardless of anything else.
-:(scenarios run)
 :(scenario forbid_redefining_scenario_even_if_forced)
 % Hide_errors = true;
 % Disable_redefine_checks = true;
@@ -817,6 +837,7 @@ void mark_autogenerated(recipe_ordinal r) {
 :(code)
 // just for the scenarios running scenarios in C++ layers
 void run_mu_scenario(const string& form) {
+  Scenario_names.clear();
   istringstream in(form);
   in >> std::noskipws;
   skip_whitespace_and_comments(in);