[bindings] Use new non-null annotation feature in cbindgen

This adds a new annotation for objects we take by reference in the
C header indicating the pointers must not be null. We have to
disable some warning clang now dumps that we haven't annotated all
pointers, as cbindgen is not yet able to add a nullable annotation.

Author: TheBlueMatt

c-bindings-gen/src/main.rs

@@ -1556,10 +1556,18 @@ fn main() {
 	let mut cpp_header_file = std::fs::OpenOptions::new().write(true).create(true).truncate(true)
 		.open(&args[6]).expect("Unable to open new header file");
 
-	writeln!(header_file, "#if defined(__GNUC__)\n#define MUST_USE_STRUCT __attribute__((warn_unused))").unwrap();
-	writeln!(header_file, "#else\n#define MUST_USE_STRUCT\n#endif").unwrap();
-	writeln!(header_file, "#if defined(__GNUC__)\n#define MUST_USE_RES __attribute__((warn_unused_result))").unwrap();
-	writeln!(header_file, "#else\n#define MUST_USE_RES\n#endif").unwrap();
+	writeln!(header_file, "#if defined(__GNUC__)").unwrap();
+	writeln!(header_file, "#define MUST_USE_STRUCT __attribute__((warn_unused))").unwrap();
+	writeln!(header_file, "#define MUST_USE_RES __attribute__((warn_unused_result))").unwrap();
+	writeln!(header_file, "#else").unwrap();
+	writeln!(header_file, "#define MUST_USE_STRUCT").unwrap();
+	writeln!(header_file, "#define MUST_USE_RES").unwrap();
+	writeln!(header_file, "#endif").unwrap();
+	writeln!(header_file, "#if defined(__clang__)").unwrap();
+	writeln!(header_file, "#define NONNULL_PTR _Nonnull").unwrap();
+	writeln!(header_file, "#else").unwrap();
+	writeln!(header_file, "#define NONNULL_PTR").unwrap();
+	writeln!(header_file, "#endif").unwrap();
 	writeln!(cpp_header_file, "#include <string.h>\nnamespace LDK {{").unwrap();
 
 	// First parse the full crate's ASTs, caching them so that we can hold references to the AST

genbindings.sh

@@ -60,9 +60,11 @@ else
 	echo "WARNING: Please install valgrind for more testing"
 fi
 
+CLANGOPTS="-Wall -Wno-nullability-completeness -pthread"
+
 # Test a statically-linked C++ version, tracking the resulting binary size and runtime
 # across debug, LTO, and cross-language LTO builds (using the same compiler each time).
-clang++ -std=c++11 -Wall -pthread demo.cpp target/debug/libldk.a -ldl
+clang++ $CLANGOPTS demo.cpp target/debug/libldk.a -ldl
 strip ./a.out
 echo " C++ Bin size and runtime w/o optimization:"
 ls -lha a.out
@@ -83,11 +85,11 @@ if [ "$HOST_PLATFORM" = "host: x86_64-unknown-linux-gnu" ]; then
 			set +e
 
 			# First the C demo app...
-			clang-$LLVM_V -std=c++11 -fsanitize=memory -fsanitize-memory-track-origins -Wall -g -pthread demo.c target/debug/libldk.a -ldl
+			clang-$LLVM_V $CLANGOPTS -fsanitize=memory -fsanitize-memory-track-origins -g demo.c target/debug/libldk.a -ldl
 			./a.out
 
 			# ...then the C++ demo app
-			clang++-$LLVM_V -std=c++11 -fsanitize=memory -fsanitize-memory-track-origins -Wall -g -pthread demo.cpp target/debug/libldk.a -ldl
+			clang++-$LLVM_V -std=c++11 $CLANGOPTS -fsanitize=memory -fsanitize-memory-track-origins -g demo.cpp target/debug/libldk.a -ldl
 			./a.out >/dev/null
 
 			# restore exit-on-failure
@@ -153,11 +155,11 @@ if [ "$HOST_PLATFORM" = "host: x86_64-unknown-linux-gnu" -o "$HOST_PLATFORM" = "
 		mv Cargo.toml.bk Cargo.toml
 
 		# First the C demo app...
-		$CLANG -fsanitize=address -Wall -g -pthread demo.c target/debug/libldk.a -ldl
+		$CLANG $CLANGOPTS -fsanitize=address -g demo.c target/debug/libldk.a -ldl
 		ASAN_OPTIONS='detect_leaks=1 detect_invalid_pointer_pairs=1 detect_stack_use_after_return=1' ./a.out
 
 		# ...then the C++ demo app
-		$CLANGPP -std=c++11 -fsanitize=address -Wall -g -pthread demo.cpp target/debug/libldk.a -ldl
+		$CLANGPP $CLANGOPTS -std=c++11 -fsanitize=address -g demo.cpp target/debug/libldk.a -ldl
 		ASAN_OPTIONS='detect_leaks=1 detect_invalid_pointer_pairs=1 detect_stack_use_after_return=1' ./a.out >/dev/null
 	else
 		echo "WARNING: Please install clang-$RUSTC_LLVM_V and clang++-$RUSTC_LLVM_V to build with address sanitizer"
@@ -168,7 +170,7 @@ fi
 
 # Now build with LTO on on both C++ and rust, but without cross-language LTO:
 CARGO_PROFILE_RELEASE_LTO=true cargo rustc -v --release -- -C lto
-clang++ -std=c++11 -Wall -flto -O2 -pthread demo.cpp target/release/libldk.a -ldl
+clang++ $CLANGOPTS -std=c++11 -flto -O2 demo.cpp target/release/libldk.a -ldl
 strip ./a.out
 echo "C++ Bin size and runtime with only RL (LTO) optimized:"
 ls -lha a.out
@@ -181,7 +183,7 @@ if [ "$HOST_PLATFORM" != "host: x86_64-apple-darwin" -a "$CLANGPP" != "" ]; then
 	# packaging than simply shipping the rustup binaries (eg Debian should Just Work
 	# here).
 	CARGO_PROFILE_RELEASE_LTO=true cargo rustc -v --release -- -C linker-plugin-lto -C lto -C link-arg=-fuse-ld=lld
-	$CLANGPP -Wall -std=c++11 -flto -fuse-ld=lld -O2 -pthread demo.cpp target/release/libldk.a -ldl
+	$CLANGPP $CLANGOPTS -flto -fuse-ld=lld -O2 demo.cpp target/release/libldk.a -ldl
 	strip ./a.out
 	echo "C++ Bin size and runtime with cross-language LTO:"
 	ls -lha a.out

lightning-c-bindings/cbindgen.toml

@@ -550,3 +550,6 @@ default_features = true
 #
 # default: []
 features = ["cbindgen"]
+
+[ptr]
+non_null_attribute = "NONNULL_PTR"