Merge pull request #1997 from tom-tan/trusted-std-stdio-File-error-flush

std.File.flush and error causes segfault after calling close

std/stdio.d

@@ -535,9 +535,21 @@ If the file is not opened, returns $(D false). Otherwise, returns
 $(WEB cplusplus.com/reference/clibrary/cstdio/ferror.html, ferror) for
 the file handle.
  */
-    @property bool error() const pure nothrow
+    @property bool error() const @trusted pure nothrow
     {
-        return !_p.handle || .ferror(cast(FILE*) _p.handle);
+        return !isOpen || .ferror(cast(FILE*) _p.handle);
+    }
+
+    unittest
+    {
+        // Issue 12349
+        static import std.file;
+        auto deleteme = testFilename();
+        auto f = File(deleteme, "w");
+        scope(exit) std.file.remove(deleteme);
+
+        f.close();
+        assert(f.error);
     }
 
 /**
@@ -634,13 +646,26 @@ for the file handle.
 
 Throws: $(D Exception) if the file is not opened or if the call to $(D fflush) fails.
  */
-    void flush()
+    void flush() @trusted
     {
         import std.exception : enforce, errnoEnforce;
 
-        errnoEnforce
-        (.fflush(enforce(_p.handle, "Calling fflush() on an unopened file"))
-                == 0);
+        enforce(isOpen, "Attempting to flush() in an unopened file");
+        errnoEnforce(.fflush(_p.handle) == 0);
+    }
+
+    unittest
+    {
+        // Issue 12349
+        static import std.file;
+        import std.exception: assertThrown;
+
+        auto deleteme = testFilename();
+        auto f = File(deleteme, "w");
+        scope(exit) std.file.remove(deleteme);
+
+        f.close();
+        assertThrown(f.flush());
     }
 
 /**