Merge pull request #352 from dtolnay/fuzz

Add fuzz target for fallback TokenStream parser

.github/workflows/ci.yml

@@ -71,6 +71,15 @@ jobs:
           target: wasm32-unknown-unknown
       - run: cargo test --target wasm32-unknown-unknown --no-run
 
+  fuzz:
+    name: Fuzz
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: dtolnay/rust-toolchain@nightly
+      - uses: dtolnay/install@cargo-fuzz
+      - run: cargo fuzz build -O
+
   clippy:
     name: Clippy
     runs-on: ubuntu-latest
@@ -99,3 +108,4 @@ jobs:
       - uses: actions/checkout@v3
       - uses: dtolnay/install@cargo-outdated
       - run: cargo outdated --workspace --exit-code 1
+      - run: cargo outdated --manifest-path fuzz/Cargo.toml --exit-code 1

fuzz/.gitignore

@@ -0,0 +1,3 @@
+artifacts/
+corpus/
+target/

fuzz/Cargo.toml

@@ -0,0 +1,21 @@
+[package]
+name = "proc-macro2-fuzz"
+version = "0.0.0"
+authors = ["David Tolnay <dtolnay@gmail.com>"]
+edition = "2021"
+publish = false
+
+[package.metadata]
+cargo-fuzz = true
+
+[dependencies]
+libfuzzer-sys = "0.4"
+proc-macro2 = { path = ".." }
+
+[[bin]]
+name = "parse_token_stream"
+path = "fuzz_targets/parse_token_stream.rs"
+test = false
+doc = false
+
+[workspace]

fuzz/fuzz_targets/parse_token_stream.rs

@@ -0,0 +1,12 @@
+#![no_main]
+
+use libfuzzer_sys::fuzz_target;
+use std::str;
+
+fuzz_target!(|bytes: &[u8]| {
+    if bytes.len() < 200 {
+        if let Ok(string) = str::from_utf8(bytes) {
+            _ = string.parse::<proc_macro2::TokenStream>();
+        }
+    }
+});