Validate block signatures w/ multiple types (#474)

The parser and typechecker allow multiple types in block signatures:

    block i32 i32
      ...
    end

But these are not currently supported in the MVP, and there is no way to
serialize them. This change makes them a validation error.

This change also fixes the default location handling of non-terminal
nodes in the parser; they used to look weird because they would use the
ending column from the last symbol in the rule, even if that symbol was
on a different line.

Fixes #473.

1 files changed, 14 insertions, 0 deletions

diff --git a/test/parse/expr/bad-loop-sig-multi.txt b/test/parse/expr/bad-loop-sig-multi.txt
new file mode 100644
index 00000000..5ea5b726
--- /dev/null
+++ b/test/parse/expr/bad-loop-sig-multi.txt
@@ -0,0 +1,14 @@
+;;; ERROR: 1
+(module
+  (func
+    loop i32 i32
+      i32.const 1
+      i32.const 2
+    end
+    drop
+    drop))
+(;; STDERR ;;;
+out/test/parse/expr/bad-loop-sig-multi.txt:4:5: multiple loop signature result types not currently supported.
+    loop i32 i32
+    ^^^^
+;;; STDERR ;;)