Define a fuzz target for the parser

cranelift/isle/fuzz/.gitignore

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+target
+corpus
+artifacts

cranelift/isle/fuzz/Cargo.toml

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+[package]
+name = "isle-fuzz"
+version = "0.0.0"
+authors = ["Automatically generated"]
+publish = false
+edition = "2018"
+
+[package.metadata]
+cargo-fuzz = true
+
+[dependencies]
+isle = { path = "../isle" }
+libfuzzer-sys = "0.4"
+
+[[bin]]
+name = "parse"
+path = "fuzz_targets/parse.rs"
+test = false
+doc = false

cranelift/isle/fuzz/fuzz_targets/parse.rs

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+#![no_main]
+
+use libfuzzer_sys::fuzz_target;
+
+fuzz_target!(|s: &str| {
+    let lexer = isle::lexer::Lexer::from_str(s, "fuzz-input.isle");
+    let mut parser = isle::parser::Parser::new(lexer);
+    let _ = parser.parse_defs();
+});