[ctor-eval] Add --ignore-external-input option (#4428)

This is meant to address one of the main limitations of wasm-ctor-eval in
emscripten atm, that libc++ global ctors will read env vars, which means they
call an import, which stops us from evalling,

emscripten-core/emscripten#15403 (comment)

To handle that, this adds an option to ignore external input. When set, we can
assume that no env vars will be read, no reading from stdin, no arguments to
main(), etc. Perhaps these could each be separate options, but I think keeping it
simple for now might be good enough.

1 files changed, 17 insertions, 0 deletions

diff --git a/test/ctor-eval/ignore-external-input.wast.out b/test/ctor-eval/ignore-external-input.wast.out
new file mode 100644
index 000000000..f728afd0e
--- /dev/null
+++ b/test/ctor-eval/ignore-external-input.wast.out
@@ -0,0 +1,17 @@
+(module
+ (type $none_=>_i32 (func (result i32)))
+ (type $none_=>_none (func))
+ (import "wasi_snapshot_preview1" "something_else" (func $wasi_something_else (result i32)))
+ (memory $0 256 256)
+ (data (i32.const 24) "aaaa")
+ (export "test3" (func $2))
+ (func $2
+  (drop
+   (call $wasi_something_else)
+  )
+  (i32.store
+   (i32.const 24)
+   (i32.const 100)
+  )
+ )
+)