[master] Add extra validation to variant instantiation (#236).

modules/variant.dt

@@ -373,6 +373,10 @@ later.)
   (and (null enumnode)
     (do (report-error mc name "atom required for variant name")
         (return (nullptr DNode))))
+  (and (or (null instances)
+           (null (@:@ instances list-node)))
+    (do (report-error mc name "list required for variant members")
+        (return (nullptr DNode))))
   (let ((lookupnode     \ (prefix-token-node mc "_Lookup" name))
         (struct-defs    \ (create-struct-defs mc enumnode instances))
         (constructors   \ (create-constructors mc name instances))

t/999last/001compile-errors.t

@@ -6,7 +6,7 @@ $ENV{"DALE_TEST_ARGS"} ||= "";
 my $test_dir = $ENV{"DALE_TEST_DIR"} || ".";
 $ENV{PATH} .= ":.";
 
-use Test::More tests => 327;
+use Test::More tests => 330;
 
 my @error_files =
     (@ARGV)

t/error-src/variant-member.dt

@@ -0,0 +1,17 @@
+(import variant)
+(import macros)
+
+(using-namespace std.macros
+  (def def-ordered-variant (macro intern (name cons)
+    (qq def-variant (uq name) cons))))
+
+(def-ordered-variant Instr
+  ((Doge ((a int)))
+   Soge
+   (Quoge ((a int) (b int)))))
+
+(def main (fn extern-c
+              int
+              ((argc int)
+               (argv (p (p char))))
+  (return 0)))

t/error-src/variant-member.dt.errors

@@ -0,0 +1,2 @@
+variant-member.dt:8:22: error: list required for variant members (see macro at 6:9)
+variant-member.dt:6:9: error: macro expansion error (see previous) (see macro at 8:1)