bindings: Don't add stray newline in trailer.

src/bindgen/bindings.rs

@@ -313,9 +313,11 @@ impl Bindings {
         if let Some(ref f) = self.config.trailer {
             out.new_line_if_not_start();
             write!(out, "{}", f);
+            if !f.ends_with('\n') {
                 out.new_line();
             }
         }
+    }
 
     fn all_namespaces(&self) -> Vec<&str> {
         if self.config.language != Language::Cxx && !self.config.cpp_compat {

tests/expectations/both/custom_header.c

@@ -1,3 +1,5 @@
 // This file is generated by cbindgen. DO NOT EDIT
 
 void root(void);
+
+/* This is a simple test to ensure that trailers don't cause extra newlines in files */

tests/expectations/both/custom_header.compat.c

@@ -9,3 +9,5 @@ void root(void);
 #ifdef __cplusplus
 } // extern "C"
 #endif // __cplusplus
+
+/* This is a simple test to ensure that trailers don't cause extra newlines in files */

tests/expectations/custom_header.c

@@ -1,3 +1,5 @@
 // This file is generated by cbindgen. DO NOT EDIT
 
 void root(void);
+
+/* This is a simple test to ensure that trailers don't cause extra newlines in files */

tests/expectations/custom_header.compat.c

@@ -9,3 +9,5 @@ void root(void);
 #ifdef __cplusplus
 } // extern "C"
 #endif // __cplusplus
+
+/* This is a simple test to ensure that trailers don't cause extra newlines in files */

tests/expectations/custom_header.cpp

@@ -5,3 +5,5 @@ extern "C" {
 void root();
 
 } // extern "C"
+
+/* This is a simple test to ensure that trailers don't cause extra newlines in files */

tests/expectations/tag/custom_header.c

@@ -1,3 +1,5 @@
 // This file is generated by cbindgen. DO NOT EDIT
 
 void root(void);
+
+/* This is a simple test to ensure that trailers don't cause extra newlines in files */

tests/expectations/tag/custom_header.compat.c

@@ -9,3 +9,5 @@ void root(void);
 #ifdef __cplusplus
 } // extern "C"
 #endif // __cplusplus
+
+/* This is a simple test to ensure that trailers don't cause extra newlines in files */

tests/rust/custom_header.toml

@@ -1,2 +1,5 @@
 no_includes = true
 header = "// This file is generated by cbindgen. DO NOT EDIT"
+trailer = """
+/* This is a simple test to ensure that trailers don't cause extra newlines in files */
+"""