analyze: borrowck: don't dump facts to disk for debugging by default

c2rust-analyze/src/borrowck/dump.rs

@@ -3,18 +3,28 @@
 use crate::borrowck::atoms::{AllFacts, AtomMaps, Loan, Origin, Output, Path, Point, Variable};
 use rustc_hash::{FxHashMap, FxHashSet};
 use std::collections::{BTreeMap, BTreeSet};
+use std::env;
 use std::error::Error;
 use std::fmt::Write as _;
 use std::fs::{self, File};
 use std::hash::Hash;
 use std::io::{BufWriter, Write};
 use std::path;
 
+thread_local! {
+    static DUMP_FACTS: bool = {
+        env::var("C2RUST_ANALYZE_DUMP_POLONIUS_FACTS").map_or(false, |val| &val == "1")
+    };
+}
+
 pub fn dump_facts_to_dir(
     facts: &AllFacts,
     maps: &AtomMaps,
     dir: impl AsRef<path::Path>,
 ) -> Result<(), Box<dyn Error>> {
+    if !DUMP_FACTS.with(|&flag| flag) {
+        return Ok(());
+    }
     let dir: &path::Path = dir.as_ref();
     fs::create_dir_all(dir)?;
     let wr = FactWriter { maps, dir };
@@ -60,6 +70,9 @@ pub fn dump_output_to_dir(
     maps: &AtomMaps,
     dir: impl AsRef<path::Path>,
 ) -> Result<(), Box<dyn Error>> {
+    if !DUMP_FACTS.with(|&flag| flag) {
+        return Ok(());
+    }
     let dir: &path::Path = dir.as_ref();
     fs::create_dir_all(dir)?;
     let wr = FactWriter { maps, dir };