Add a CI test for cargoless use of clippy-driver

ci/base-tests.sh

@@ -25,6 +25,30 @@ export CARGO_TARGET_DIR=`pwd`/target/
 ./util/dev update_lints --check
 cargo +nightly fmt --all -- --check
 
+# Check running clippy-driver without cargo
+(
+  export LD_LIBRARY_PATH=$(rustc --print sysroot)/lib
+
+  # Check sysroot handling
+  sysroot=$(./target/debug/clippy-driver --print sysroot)
+  test $sysroot = $(rustc --print sysroot)
+
+  sysroot=$(./target/debug/clippy-driver --sysroot /tmp --print sysroot)
+  test $sysroot = /tmp
+
+  sysroot=$(SYSROOT=/tmp ./target/debug/clippy-driver --print sysroot)
+  test $sysroot = /tmp
+
+  # Make sure this isn't set - clippy-driver should cope without it
+  unset CARGO_MANIFEST_DIR
+
+  # Run a lint and make sure it produces the expected output
+  ./target/debug/clippy-driver --emit metadata --crate-type bin tests/ui/cstring.rs 2> cstring.stderr
+  diff cstring.stderr tests/ui/cstring.stderr
+
+  # TODO: CLIPPY_CONF_DIR / CARGO_MANIFEST_DIR
+)
+
 # make sure tests are formatted
 
 # some lints are sensitive to formatting, exclude some files