Enable and fix more GCC warnings by MarcelRaad · Pull Request #2747 · curl/curl

MarcelRaad · 2018-07-14T11:11:59Z

This enables the following GCC flags:

When building with --enable-werror:

-pedantic-errors for GCC >= 5, which rejects some constructs which are no valid C and turns some undefined behavior into compile errors

When building with --enable-warnings:

-Wbad-function-cast, which was already enabled for clang, but not for GCC as it's a little stricter there - would have found telnet.c warning #2696 also with GCC
-Wimplicit-fallthrough=4 instead of the default 3, which makes the fallthrough comments more uniform
-Wold-style-definition
-ftree-vrp and -fdelete-null-pointer-checks, so that -Warray-bounds and -Wnull-dereference also work without --enable-optimize
level 2 instead of the default level 1 for -Wformat, -Warray-bounds, and -Wunused-const-variable

Also removes some unused definitions, but unfortunately the corresponding warning flag cannot be enabled as some occurrences are hard to fix.

Tested with

GCC 4.4 through 7 on Ubuntu 16.04 targeting Linux, Win64, Win32
GCC 4.8 on OpenSUSE Leap 42
GCC 4.8 on SLES 12
GCC 6 on MinGW/MSYS
GCC 7 on MinGW-w64/MSYS2 targeting Win64, Win32, MSYS
GCC 7 on Cygwin

bagder · 2018-07-16T18:56:48Z

tests/libtest/lib650.c

  struct curl_forms formarray[3];
  size_t formlength = 0;
  char flbuf[32];
+  long contentlength = 0;


shouldn't this be a curl_off_t ?

The deprecated CURLFORM_CONTENTSLENGTH used here uses long. I used the same cast sequence as in formdata.c. The newer CURLFORM_CONTENTLEN uses curl_off_t. If you want, I can switch to that in a separate commit before this one.

bagder · 2018-07-16T18:57:10Z

tests/libtest/lib650.c

  formarray[0].value = data;
  formarray[1].option = CURLFORM_CONTENTSLENGTH;
-  formarray[1].value = (char *) strlen(data) - 1;
+  formarray[1].value = (char *)(size_t)contentlength;


and this too. Even if they're highly likely to use the same size...

bagder · 2018-07-16T18:57:20Z

tests/libtest/lib650.c

    goto test_cleanup;
  }

+  contentlength = (long)(strlen(data) - 1);


... and this

bagder · 2018-08-21T11:30:47Z

@MarcelRaad, what's the reason this is marked for next feature window and can't go in already now?

MarcelRaad · 2018-08-21T11:47:07Z

@bagder The reason at that time was that I thought I wouldn't have enough time to see if all autobuilds pass without new warnings and fix them if not for 7.61.1. As the release date is now September 5, I'll merge right now and watch the autobuilds. Thanks!

bagder · 2018-08-21T11:48:37Z

Excellent! 👍

Closes curl#2747

Enable pedantic-errors for GCC >= 5 with --enable-werror. Before GCC 5, pedantic-errors was synonymous to -Werror=pedantic [0], which is still the case for clang [1]. With GCC 5, it became complementary [2]. Also fix a resulting error in acinclude.m4 as main's return type was missing, which is illegal in C99. [0] https://gcc.gnu.org/onlinedocs/gcc-4.9.0/gcc/Warning-Options.html [1] https://clang.llvm.org/docs/UsersManual.html#options-to-control-error-and-warning-messages [2] https://gcc.gnu.org/onlinedocs/gcc-5.1.0/gcc/Warning-Options.html Closes curl#2747

This warning used to be enabled only for clang as it's a bit stricter on GCC. Silence the remaining occurrences and enable it on GCC too. Closes curl#2747

This enables level 4 instead of the default level 3, which of the currently used comments only allows /* FALLTHROUGH */ to silence the warning. Closes curl#2747

This enables the following additional warnings: -Wold-style-definition -Warray-bounds=2 instead of the default 1 -Wformat=2, but only for GCC 4.8+ as Wno-format-nonliteral is not respected for older versions -Wunused-const-variable, which enables level 2 instead of the default 1 -Warray-bounds also in debug mode through -ftree-vrp -Wnull-dereference also in debug mode through -fdelete-null-pointer-checks Closes curl#2747

Enable pedantic-errors for GCC >= 5 with --enable-werror. Before GCC 5, pedantic-errors was synonymous to -Werror=pedantic [0], which is still the case for clang [1]. With GCC 5, it became complementary [2]. Also fix a resulting error in acinclude.m4 as main's return type was missing, which is illegal in C99. [0] https://gcc.gnu.org/onlinedocs/gcc-4.9.0/gcc/Warning-Options.html [1] https://clang.llvm.org/docs/UsersManual.html#options-to-control-error-and-warning-messages [2] https://gcc.gnu.org/onlinedocs/gcc-5.1.0/gcc/Warning-Options.html Closes curl#2747

This warning used to be enabled only for clang as it's a bit stricter on GCC. Silence the remaining occurrences and enable it on GCC too. Closes curl#2747

This enables level 4 instead of the default level 3, which of the currently used comments only allows /* FALLTHROUGH */ to silence the warning. Closes curl#2747

This enables the following additional warnings: -Wold-style-definition -Warray-bounds=2 instead of the default 1 -Wformat=2, but only for GCC 4.8+ as Wno-format-nonliteral is not respected for older versions -Wunused-const-variable, which enables level 2 instead of the default 1 -Warray-bounds also in debug mode through -ftree-vrp -Wnull-dereference also in debug mode through -fdelete-null-pointer-checks Closes curl#2747

MarcelRaad added build feature-window A merge of this requires an open feature window labels Jul 14, 2018

bagder approved these changes Jul 16, 2018

View reviewed changes

MarcelRaad removed the feature-window A merge of this requires an open feature window label Aug 21, 2018

MarcelRaad added 5 commits August 21, 2018 14:03

Remove unused definitions

68730e4

Closes curl#2747

curl-compilers: enable -Wbad-function-cast on GCC

5f5ff5a

This warning used to be enabled only for clang as it's a bit stricter on GCC. Silence the remaining occurrences and enable it on GCC too. Closes curl#2747

curl-compilers: enable -Wimplicit-fallthrough=4 for GCC

f5101cf

This enables level 4 instead of the default level 3, which of the currently used comments only allows /* FALLTHROUGH */ to silence the warning. Closes curl#2747

MarcelRaad force-pushed the gcc-warnings branch from 7e605fb to 7e34a58 Compare August 21, 2018 12:04

MarcelRaad closed this in a829c4b Aug 21, 2018

MarcelRaad deleted the gcc-warnings branch August 21, 2018 16:57

lock bot locked as resolved and limited conversation to collaborators Nov 19, 2018

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Enable and fix more GCC warnings#2747

Enable and fix more GCC warnings#2747
MarcelRaad wants to merge 5 commits intocurl:masterfrom
MarcelRaad:gcc-warnings

MarcelRaad commented Jul 14, 2018

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