fix msvc passthrough arguments

mozilla#764 and its followon patch, mozilla#768, failed to take into account that
passthrough arguments actually need to be passed through to the compiler
invocation: they don't prevent caching, but they do need to be
considered when computing the cache key...and when actually performing
the compilation.

src/compiler/msvc.rs

@@ -500,6 +500,12 @@ pub fn parse_arguments(
                 arg.normalize(NormalizedDisposition::Concatenated)
                     .iter_os_strings(),
             ),
+            Some(PassThrough) | Some(PassThroughWithPath(_)) | Some(PassThroughWithSuffix(_)) => {
+                common_args.extend(
+                    arg.normalize(NormalizedDisposition::Concatenated)
+                        .iter_os_strings(),
+                )
+            }
             _ => {}
         }
     }
@@ -1086,6 +1092,37 @@ mod test {
         );
     }
 
+    #[test]
+    fn test_parse_arguments_passthrough() {
+        let args = ovec![
+            "-Oy",
+            "-Gw",
+            "-EHa",
+            "-Fmdictionary-map",
+            "-c",
+            "-Fohost_dictionary.obj",
+            "dictionary.c"
+        ];
+        let ParsedArguments {
+            input,
+            common_args,
+            dependency_args,
+            preprocessor_args,
+            ..
+        } = match parse_arguments(args) {
+            CompilerArguments::Ok(args) => args,
+            o => panic!("Got unexpected parse result: {:?}", o),
+        };
+        assert_eq!(Some("dictionary.c"), input.to_str());
+        assert!(preprocessor_args.is_empty());
+        assert!(dependency_args.is_empty());
+        assert!(!common_args.is_empty());
+        assert_eq!(
+            common_args,
+            ovec!("-Oy", "-Gw", "-EHa", "-Fmdictionary-map")
+        );
+    }
+
     #[test]
     fn test_parse_arguments_too_many_inputs() {
         assert_eq!(