Structs, arrays, owned strings, memory model, modules, debug info

- struct with default values; constructors Point(1, 2) / Point(x: 1); field access, auto-deref through pointers
- []T arrays with bounds checks, literals, for-each, push/pop/insert/remove/clear/resize/find/contains/join/slice/reverse/sort
- str carries its length: .len, s[i], +, comparison, sub/find/split/trim/upper/lower/replace/repeat/bytes, str(x), int(s), float(s)
- Memory: values own their memory and are freed at the end of their block; assignment copies, temporaries move;
  parameters are lent and only copied when the function changes them; defer; new()/free() for manual heap memory
- input(), read_file/write_file/file_exists, exit(), fn main([]str args)
- Finch modules: import name, module.fn(), module.Struct
- C structs from headers (fields, fixed arrays, nested); passed and returned by value with the System V x86-64 ABI;
  addr(fn) gives C a callback
- link "file.c" compiles and links your own C code
- -g emits DWARF debug info (gdb/lldb)
- Small C runtime (runtime/finch_rt.c) embedded in the compiler, cached in ~/.cache/finch
- Tests: 58, all clean under valgrind (MEMCHECK=1 tests/run.sh)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/run.sh

@@ -1,27 +1,45 @@
 #!/usr/bin/env bash
 # Finch test suite.
 #   tests/run/*.fn   must compile and print exactly what is in the matching .out file
+#                    (files without `fn main` are modules or helpers and are skipped;
+#                     a matching .in file is fed to the program as its input)
 #   tests/fail/*.fn  must fail; the first line is "// expect: <text that must appear in the error>"
+#   MEMCHECK=1 tests/run.sh   also runs every program under valgrind: no leaks, no bad memory access
 set -u
 cd "$(dirname "$0")"
 FINCH=${FINCH:-../build/finch}
 pass=0; failed=0
+tmp=$(mktemp -d)
+trap 'rm -rf "$tmp"' EXIT
 
 for f in run/*.fn; do
+    grep -q "^fn main" "$f" || continue
     want="${f%.fn}.out"
-    got=$("$FINCH" run "$f" 2>&1)
-    if [ "$got" == "$(cat "$want")" ]; then
-        pass=$((pass + 1))
-    else
+    input="${f%.fn}.in"
+    [ -f "$input" ] || input=/dev/null
+    got=$("$FINCH" run "$f" < "$input" 2>&1)
+    if [ "$got" != "$(cat "$want")" ]; then
         failed=$((failed + 1))
         echo "FAIL $f"
         diff <(echo "$got") "$want" | head -20
+        continue
     fi
+    if [ "${MEMCHECK:-0}" = 1 ]; then
+        exe="$tmp/$(basename "${f%.fn}")"
+        "$FINCH" build "$f" -o "$exe" >/dev/null 2>&1
+        if ! valgrind -q --leak-check=full --errors-for-leak-kinds=all --error-exitcode=99 "$exe" < "$input" >/dev/null 2>"$tmp/vg"; then
+            failed=$((failed + 1))
+            echo "MEMCHECK FAIL $f"
+            head -20 "$tmp/vg"
+            continue
+        fi
+    fi
+    pass=$((pass + 1))
 done
 
 for f in fail/*.fn; do
     expect=$(head -1 "$f" | sed -n 's|^// expect: ||p')
-    got=$("$FINCH" run "$f" 2>&1)
+    got=$("$FINCH" run "$f" < /dev/null 2>&1)
     status=$?
     if [ $status -ne 0 ] && [[ "$got" == *"$expect"* ]]; then
         pass=$((pass + 1))