A customer reported a problem with a system header file. When they included ole2.h<\/tt>, the compiler reported an error in oaidl.h<\/tt>:<\/p>\n The error message is<\/p>\n The compiler is seeing ghosts: It’s complaining about things that aren’t there, like -><\/tt> and Log.<\/p>\n When you see the compiler reporting errors about things that aren’t in the code, you should suspect a macro, because macros can insert characters into code.<\/p>\n In this case, I suspected that there is a macro called The customer reported that they had no such macro.<\/p>\n I asked them to generate a preprocessor file for the code that isn’t compiling. That way, we can see what is being produced by the preprocessor before it goes into the part of the compiler that is complaining about the illegal use of -><\/tt>. Is there really no -><\/tt> there?<\/p>\n The customer reported back that, oops, they did indeed have a macro called The compiler can at times be obtuse with its error messages, but as far as I know, it isn’t malicious. If it complains about a misused -><\/tt>, then there is probably a -><\/tt> that is being misused.<\/p>\n","protected":false},"excerpt":{"rendered":" If the compiler is complaining about things you didn’t write, find out who wrote them.<\/p>\n","protected":false},"author":1069,"featured_media":111744,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[1],"tags":[25],"class_list":["post-112208","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-oldnewthing","tag-code"],"acf":[],"blog_post_summary":" If the compiler is complaining about things you didn’t write, find out who wrote them.<\/p>\n","_links":{"self":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts\/112208","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/users\/1069"}],"replies":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/comments?post=112208"}],"version-history":[{"count":0,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts\/112208\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/media\/111744"}],"wp:attachment":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/media?parent=112208"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/categories?post=112208"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/tags?post=112208"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}} MIDL_INTERFACE(\"3127CA40-446E-11CE-8135-00AA004BB851\")\r\n IErrorLog : public IUnknown\r\n {\r\n public:\r\n virtual HRESULT STDMETHODCALLTYPE AddError(<\/span> \/\/ error here\r\n \/* [in] *\/ __RPC__in LPCOLESTR pszPropName,\r\n \/* [in] *\/ __RPC__in EXCEPINFO *pExcepInfo) = 0;\r\n \r\n };\r\n<\/pre>\noaidl.h(5457,43): error C3927: '->': trailing return type is not allowed after a non-function declarator\r\noaidl.h(5457,43): error C3613: missing return type after '->' ('int' assumed)\r\noaidl.h(5457,43): error C3646: 'Log': unknown override specifier\r\noaidl.h(5457,43): error C2275: 'LPCOLESTR': expected an expression instead of a type\r\noaidl.h(5457,43): error C2146: syntax error: missing ')' before identifier 'pszPropName'\r\noaidl.h(5459,60): error C2238: unexpected token(s) preceding ';'\r\n<\/pre>\nAddError<\/code> whose expansion includes the token -><\/tt>.<\/p>\nAddError<\/code>. Disabling the macro fixed the problem.<\/p>\n