Fuzzer: Distinguish traps from host limitations (#3801)

Host limitations are arbitrary and can be modified by optimizations, so
ignore them. For example, if the optimizer removes allocations then a
host limit on an allocation error may vanish. Or, an optimization that
removes recursion and replaces it with a loop may avoid a host limit
on call depth (that is not done currently, but might some day).

This removes a class of annoying false positives in the fuzzer.

1 files changed, 15 insertions, 0 deletions

diff --git a/test/passes/Oz_fuzz-exec_all-features.wast b/test/passes/Oz_fuzz-exec_all-features.wast
index 4092f6b34..c88133c3a 100644
--- a/test/passes/Oz_fuzz-exec_all-features.wast
+++ b/test/passes/Oz_fuzz-exec_all-features.wast
@@ -240,3 +240,18 @@
   )
  )
 )
+(module
+ (type $[mut:i8] (array (mut i8)))
+ (func "foo" (result i32)
+  ;; before opts this will trap on failing to allocate -1 >>> 0 bytes. after
+  ;; opts the unused value is removed so there is no trap, and a value is
+  ;; returned, which should not confuse the fuzzer.
+  (drop
+   (array.new_default_with_rtt $[mut:i8]
+    (i32.const -1)
+    (rtt.canon $[mut:i8])
+   )
+  )
+  (i32.const 0)
+ )
+)