Make the verify pass on by default

As we slowly move towards Pony 1.0.0, fixing issues in LLVM IR
generation is an important consideration. We've turned on
LLVM IR generation verification as a default in the compiler.

Hopefully this will generate reports for failures that are
currently hidden in the wild.

.release-notes/always-verify-ir.md

@@ -0,0 +1,7 @@
+## Turn on `verify` pass by default
+
+The `verify` compiler pass will check the LLVM IR generated for the program being compiled for errors. Previously, you had to turn verify on. It is now on by default and can be turned off using the new `--noverify` option.
+
+We decided to turn on the pass for two reasons. The first is that it adds very little overhead to normal compilation times. The second is it will help generate error reports from Pony users for lurking bugs in our code generation.
+
+The errors reported don't generally result in incorrect programs, but could under the right circumstance. We feel that turning on the reports will allow us to find and fix bugs quicker and help move us closer to Pony version 1.

src/libponyc/options/options.c

@@ -53,7 +53,7 @@ enum
   OPT_TRACE,
   OPT_WIDTH,
   OPT_IMMERR,
-  OPT_VERIFY,
+  OPT_NOVERIFY,
   OPT_FILENAMES,
   OPT_CHECKTREE,
   OPT_EXTFUN,
@@ -99,7 +99,7 @@ static opt_arg_t std_args[] =
   {"trace", 't', OPT_ARG_NONE, OPT_TRACE},
   {"width", 'w', OPT_ARG_REQUIRED, OPT_WIDTH},
   {"immerr", '\0', OPT_ARG_NONE, OPT_IMMERR},
-  {"verify", '\0', OPT_ARG_NONE, OPT_VERIFY},
+  {"noverify", '\0', OPT_ARG_NONE, OPT_NOVERIFY},
   {"files", '\0', OPT_ARG_NONE, OPT_FILENAMES},
   {"checktree", '\0', OPT_ARG_NONE, OPT_CHECKTREE},
   {"extfun", '\0', OPT_ARG_NONE, OPT_EXTFUN},
@@ -271,6 +271,9 @@ ponyc_opt_process_t ponyc_opt_process(opt_state_t* s, pass_opt_t* opt,
 
   bool wants_help = false;
 
+  // default to running verify pass. require it to be turned off.
+  opt->verify = true;
+
   while((id = ponyint_opt_next(s)) != -1)
   {
     switch(id)
@@ -339,7 +342,7 @@ ponyc_opt_process_t ponyc_opt_process(opt_state_t* s, pass_opt_t* opt,
       case OPT_TRACE: opt->parse_trace = true; break;
       case OPT_WIDTH: opt->ast_print_width = atoi(s->arg_val); break;
       case OPT_IMMERR: errors_set_immediate(opt->check.errors, true); break;
-      case OPT_VERIFY: opt->verify = true; break;
+      case OPT_NOVERIFY: opt->verify = false; break;
       case OPT_EXTFUN: opt->extfun = true; break;
       case OPT_FILENAMES: opt->print_filenames = true; break;
       case OPT_CHECKTREE: opt->check_tree = true; break;