Fix cache collision with object file and precompiled headers

src/compiler/c.rs

@@ -1448,6 +1448,42 @@ mod test {
         );
     }
 
+    #[test]
+    fn test_header_differs() {
+        let args = ovec!["a", "b", "c"];
+        const PREPROCESSED: &[u8] = b"hello world";
+        assert_neq!(
+            hash_key("abcd", Language::C, &args, &[], &[], PREPROCESSED, false),
+            hash_key(
+                "abcd",
+                Language::CHeader,
+                &args,
+                &[],
+                &[],
+                PREPROCESSED,
+                false
+            )
+        );
+    }
+
+    #[test]
+    fn test_plusplus_header_differs() {
+        let args = ovec!["a", "b", "c"];
+        const PREPROCESSED: &[u8] = b"hello world";
+        assert_neq!(
+            hash_key("abcd", Language::Cxx, &args, &[], &[], PREPROCESSED, true),
+            hash_key(
+                "abcd",
+                Language::CxxHeader,
+                &args,
+                &[],
+                &[],
+                PREPROCESSED,
+                true
+            )
+        );
+    }
+
     #[test]
     fn test_hash_key_executable_contents_differs() {
         let args = ovec!["a", "b", "c"];

src/compiler/compiler.rs

@@ -146,8 +146,10 @@ impl Language {
 
     pub fn as_str(self) -> &'static str {
         match self {
-            Language::C | Language::CHeader => "c",
-            Language::Cxx | Language::CxxHeader => "c++",
+            Language::C => "c",
+            Language::CHeader => "cHeader",
+            Language::Cxx => "c++",
+            Language::CxxHeader => "c++Header",
             Language::GenericHeader => "c/c++",
             Language::ObjectiveC => "objc",
             Language::ObjectiveCxx => "objc++",