-
-
Notifications
You must be signed in to change notification settings - Fork 6.3k
New issue
Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.
By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.
Already on GitHub? Sign in to your account
RFC: silence benign warning with pragma #3263
RFC: silence benign warning with pragma #3263
Conversation
Commit 5bfaa86 introduced a new compiler warning on Windows cross compilation with GCC. The coding is however a documented pattern for acquiring a handle to write to, so rather than changing working code this wraps the offending cast in a GCC diagnostic pragma to silence the warning. See below for an example of the warning from the autobuild logs (whitespace edited to fit): /src/tool_cb_wrt.c:175:9: warning: cast from function call of type 'intptr_t {aka long long int}' to non-matching type 'void *' [-Wbad-function-cast] (HANDLE) _get_osfhandle(fileno(outs->stream)), ^
I think you just have to store the result of the function call in an intermediate variable to suppress the warning. That would maybe be less verbose? At least that's what I did in other places. |
According to this, this workaround will silence it without using pragmas: --- a/src/tool_cb_wrt.c
+++ b/src/tool_cb_wrt.c
@@ -161,6 +161,7 @@ size_t tool_write_cb(char *buffer, size_t sz, size_t nmemb, void *userdata)
DWORD in_len = (DWORD)(sz * nmemb);
wchar_t* wc_buf;
DWORD wc_len;
+ intptr_t fhnd = _get_osfhandle(fileno(outs->stream));
/* calculate buffer size for wide characters */
wc_len = MultiByteToWideChar(CP_UTF8, 0, buffer, in_len, NULL, 0);
@@ -172,7 +173,7 @@ size_t tool_write_cb(char *buffer, size_t sz, size_t nmemb, void *userdata)
wc_len = MultiByteToWideChar(CP_UTF8, 0, buffer, in_len, wc_buf, wc_len);
if(!WriteConsoleW(
- (HANDLE) _get_osfhandle(fileno(outs->stream)),
+ (HANDLE) fhnd,
wc_buf,
wc_len,
&wc_len, I can confirm the above silences the warning, using this command: $ x86_64-w64-mingw32-gcc -c tool_cb_wrt.c -I../include -I../lib -Wbad-function-cast (One issue with |
Commit 5bfaa86 introduced a new compiler warning on Windows cross compilation with GCC. See below for an example of the warning from the autobuild logs (whitespace edited to fit): /src/tool_cb_wrt.c:175:9: warning: cast from function call of type 'intptr_t {aka long long int}' to non-matching type 'void *' [-Wbad-function-cast] (HANDLE) _get_osfhandle(fileno(outs->stream)), ^ Store the return value from _get_osfhandle() in an intermediate variable and cast the variable in WriteConsoleW() rather than the function call directly to avoid a compiler warning. In passing, also add inspection of the MultiByteToWideChar() return value and return failure in case an error is reported.
Perfect, that's a much better solution! I've pushed an updated commit which will be squashed if accepted. In passing I also noticed that the possibility of an error from |
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
Thanks!
Disclaimer: I don't have a system to reproduce the warning, and test the fix, on so this is perhaps more of a discussion piece than a patch. Anyways, here goes.
Commit 5bfaa86 introduced a new compiler warning on Windows cross compilation with GCC. The coding is however a documented pattern for acquiring a handle to write to, so rather than changing working code this wraps the offending cast in a GCC diagnostic pragma to silence the warning. See below for an example of the warning from the autobuild logs:
An example failing build can be found here: https://curl.haxx.se/dev/log.cgi?id=20181111190642-17820#prob1