Refactor type and function parsing (#2143)

- Refactored & fixed typeuse parsing rules so now the rules more closely
  follow the spec. There have been multiple parsing rules that were
  different in subtle ways, which are supposed to be the same according
  to the spec.
  - Duplicate types, i.e., types with the same signature, in the type
    section are allowed as long as they don't have the same given name.
    If a name is given, we use it; if type name is not given, we
    generate one in the form of `$FUNCSIG$` + signature string. If the
    same generated name already exists in the type section, we append
    `_` at the end. This causes most of the changes in the autogenerated
    type names in test outputs.
  - A typeuse has to be in the order of (type) -> (param) -> (result),
    if more than one of them exist. In case of function definitions,
    (local) has to be after all of these. Fixed some test cases that
    violate this rule.
  - When only (param)/(result) are given, its type will be the type with
    the smallest existing type index whose parameter and result are the
    same. If there's no such type, a new type will be created and
    inserted.
  - Added a test case `duplicate_types.wast` to test type namings for
    duplicate types.

- Refactored `parseFunction` function.

- Add more overrides to helper functions: `getSig` and
  `ensureFunctionType`.

1 files changed, 2 insertions, 2 deletions

diff --git a/test/passes/simplify-locals-notee.txt b/test/passes/simplify-locals-notee.txt
index bf5b17d07..66cf78ead 100644
--- a/test/passes/simplify-locals-notee.txt
+++ b/test/passes/simplify-locals-notee.txt
@@ -1,6 +1,6 @@
 (module
- (type $0 (func))
- (func $contrast (; 0 ;) (type $0)
+ (type $FUNCSIG$v (func))
+ (func $contrast (; 0 ;) (type $FUNCSIG$v)
   (local $x i32)
   (local $y i32)
   (local $z i32)