build: fix compiler warnings in feature detections by vszakats · Pull Request #16287 · curl/curl

vszakats · 2025-02-10T12:16:01Z

Fix or silence compiler warnings happening in feature detections
to reduce log noise. Warnings may also get promoted to errors in certain
cases, causing missed detections.

It reduces the number of warnings by 4500+ across the linux, linux-old,
macos, non-native and windows GHA workflows (~142 jobs).

Also move picky warning logic for MSVC/Borland to
`CMake/PickyWarnings.cmake. To make them listed in the picky-warnings
log output, and to also apply to feature detections to make them compile
under the same conditions as source code. The hope is to help catching
issues faster. It also improves code quality of feature tests.

Fixed/silenced:

warning #177: variable "dummy" was declared but never referenced
warning #177: variable "flag" was declared but never referenced
warning #177: variable "res" was declared but never referenced
warning #592: variable "s" is used before its value is set
warning #1011: missing return statement at end of non-void function "main"
warning #1786: function "SSL_CTX_set_srp_password" (declared at line 1888 of "/usr/include/openssl/ssl.h") was declared deprecated ("Since OpenSSL 3.0")
warning #1786: function "SSL_CTX_set_srp_username" (declared at line 1887 of "/usr/include/openssl/ssl.h") was declared deprecated ("Since OpenSSL 3.0")
warning #2332: a value of type "const char *" cannot be assigned to an entity of type "char *" (dropping qualifiers)
warning: 'SSL_CTX_set_srp_password' is deprecated [-Wdeprecated-declarations]
warning: 'SSL_CTX_set_srp_password' is deprecated: Since OpenSSL 3.0 [-Wdeprecated-declarations]
warning: 'SSL_CTX_set_srp_username' is deprecated [-Wdeprecated-declarations]
warning: 'SSL_CTX_set_srp_username' is deprecated: Since OpenSSL 3.0 [-Wdeprecated-declarations]
warning: 'b' is used uninitialized [-Wuninitialized]
warning: 'gethostname' redeclared without dllimport attribute: previous dllimport ignored [-Wattributes]
warning: Undefined or garbage value returned to caller [core.uninitialized.UndefReturn]
warning: Value stored to 'i' is never read [deadcode.DeadStores]
warning: assigning to 'char *' from 'const char *' discards qualifiers [-Wincompatible-pointer-types-discards-qualifiers]
warning: assignment discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers]
warning: control reaches end of non-void function [-Wreturn-type]
warning: empty expression statement has no effect; remove unnecessary ';' to silence this warning [-Wextra-semi-stmt]
warning: excess elements in struct initializer
warning: initialization discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers]
warning: macro "_FILE_OFFSET_BITS" is not used [-Wunused-macros]
warning: macro "_REENTRANT" is not used [-Wunused-macros]
warning: missing braces around initializer [-Wmissing-braces]
warning: no previous extern declaration for non-static variable 'off_t_is_large' [-Wmissing-variable-declarations]
warning: no previous prototype for 'check' [-Wmissing-prototypes]
warning: no previous prototype for function 'check' [-Wmissing-prototypes]
warning: null argument where non-null required (argument 2) [-Wnonnull]
warning: passing 'const char[1]' to parameter of type 'char *' discards qualifiers [-Wincompatible-pointer-types-discards-qualifiers]
warning: passing argument 2 of 'SSL_CTX_set_srp_password' discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers]
warning: passing argument 2 of 'SSL_CTX_set_srp_username' discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers]
warning: unused parameter 'c' [-Wunused-parameter]
warning: unused parameter 'f' [-Wunused-parameter]
warning: unused variable 'data' [-Wunused-variable]
warning: unused variable 'dummy' [-Wunused-variable]
warning: unused variable 'flag' [-Wunused-variable]
warning: unused variable 'res' [-Wunused-variable]
warning: unused variable 's' [-Wunused-variable]
warning: variable 's' set but not used [-Wunused-but-set-variable]
warning: variable 'ts' set but not used [-Wunused-but-set-variable]

w/o whitespace: https://github.com/curl/curl/pull/16287/files?w=1

rebase on cmake: fix/add missing feature detections for Windows/MS-DOS #16278.
disable Windows pre-fill for double checking results.

Warnings possibly fixable, but not fixed in this PR:

ld: warning: ignoring duplicate libraries: '-lcrypto'
ld: warning: ignoring duplicate libraries: '-lcrypto', '-lnghttp2', '-lssl'
ld: warning: ignoring duplicate libraries: '-lcrypto', '-lrtmp', '-lssl'
ld: warning: ignoring duplicate libraries: '-lcrypto', '-lssl'

warning #1786: function "siginterrupt" (declared at line 324 of "/usr/include/signal.h") was declared deprecated ("Use sigaction with SA_RESTART instead")
warning: 'siginterrupt' is deprecated: Use sigaction with SA_RESTART instead [-Wdeprecated-declarations]

warning #2193: null argument provided for parameter marked with attribute "nonnull"
warning: Null pointer passed to 1st parameter expecting 'nonnull' [core.NonNullParamChecker]
warning: Null pointer passed to 2nd parameter expecting 'nonnull' [core.NonNullParamChecker]
warning: Null pointer passed to 3rd parameter expecting 'nonnull' [core.NonNullParamChecker]
warning: argument 1 null where non-null expected [-Wnonnull]
warning: argument 2 null where non-null expected [-Wnonnull]
warning: argument 3 null where non-null expected [-Wnonnull]
warning: null argument where non-null required (argument 1) [-Wnonnull]
warning: null passed to a callee that requires a non-null argument [-Wnonnull]

warning: 'ber_free' is deprecated: first deprecated in macOS 10.11 - use OpenDirectory Framework [-Wdeprecated-declarations]
warning: 'ber_init' is deprecated: first deprecated in macOS 10.11 - use OpenDirectory Framework [-Wdeprecated-declarations]
warning: 'ldap_init' is deprecated: first deprecated in macOS 10.10 - use ldap_initialize [-Wdeprecated-declarations]
warning: 'ldap_unbind' is deprecated: first deprecated in macOS 10.10 - use ldap_unbind_ext [-Wdeprecated-declarations]

warning: unused variable 'hdata' [-Wunused-variable]
warning: unused variable 'ts' [-Wunused-variable]

A deprecation error prevented correct detection in MSVC UWP builds: ``` curl\\bld\\CMakeFiles\\CMakeScratch\\TryCompile-ks2aa4\\CheckSymbolExists.c(8,19): error C4996: 'SSL_CTX_set_srp_username': Since OpenSSL 3.0 ``` Ref: https://github.com/curl/curl/actions/runs/13242285473/job/36960223663#step:8:898 It seems to be caused by different default warning levels used by the toolchain (or CMake?): `/W3` for UWP and `/W1` for Windows desktop. https://github.com/curl/curl/actions/runs/13242285473/job/36960223663#step:8:893 UWP https://github.com/curl/curl/actions/runs/13242285473/job/36960223262#step:8:445 desktop Fix by passing the OpenSSL macro suppressing its deprecation warnings. Cherry-picked from #16287 Closes #16293

To make it listed in the picky-warning log message, and to apply to feature detections, to make them more robust and compile under the same conditions as the source code. The hope is this helps catching issues faster. It also improves code quality of feature tests.

``` /cygdrive/d/a/curl/curl/CMake/CurlTests.c: In function 'check': /cygdrive/d/a/curl/curl/CMake/CurlTests.c:298:17: error: unused parameter 'c' [-Werror=unused-parameter] 298 | void check(char c) {} | ~~~~~^ ``` https://github.com/curl/curl/actions/runs/13209220246/job/36879343197#step:7:4493 CurlTests.c: fix more compiler warnings

MSVC: ``` D:\\a\\curl\\curl\\CMake\\CurlTests.c(171,17): warning C4189: 'flags': local variable is initialized but not referenced [D:\\a\\curl\\curl\\bld\\CMakeFiles\\CMakeTmp\\cmTC_41ff3.vcxproj] ``` https://github.com/curl/curl/actions/runs/13215270720/job/36893785298?pr=16238#step:7:7204

``` D:\\a\\curl\\curl\\CMake\\CurlTests.c(133,6): warning C4127: conditional expression is constant [D:\\a\\curl\\curl\\bld\\CMakeFiles\\CMakeTmp\\cmTC_1d26c.vcxproj] ``` https://github.com/curl/curl/actions/runs/13216319022/job/36896009461?pr=16238#step:8:7888

``` D:/a/curl/curl/CMake/CurlTests.c:286:3: warning: empty expression statement has no effect; remove unnecessary ';' to silence this warning [-Wextra-semi-stmt] ``` https://github.com/curl/curl/actions/runs/13226709122/job/36921490343?pr=16278

``` D:/a/curl/curl/CMake/CurlTests.c:154:5: warning: no previous extern declaration for non-static variable 'off_t_is_large' [-Wmissing-variable-declarations] 154 | int off_t_is_large[(LARGE_OFF_T % 2147483629 == 721 | ^ D:/a/curl/curl/CMake/CurlTests.c:154:1: note: declare 'static' if the variable is not intended to be used outside of this translation unit 154 | int off_t_is_large[(LARGE_OFF_T % 2147483629 == 721 | ^ ``` https://github.com/curl/curl/actions/runs/13226709122/job/36921490343?pr=16278#step:8:3911

``` /d/a/curl/curl/CMake/CurlTests.c:80:23: warning: unused variable ‘hdata’ [-Wunused-variable] 80 | struct hostent_data hdata; | ^~~~~ ``` https://github.com/curl/curl/actions/runs/13226709122/job/36921489357?pr=16278#step:8:3941 (msys2) https://github.com/curl/curl/actions/runs/13226709122/job/36921488213?pr=16278#step:7:3952 (cygwin)

mingw gcc: ``` D:/a/curl/curl/CMake/CurlTests.c:61:12: error: "_REENTRANT" redefined 61 | # define _REENTRANT | ^~~~~~~~~~ <command-line>: note: this is the location of the previous definition ``` https://github.com/curl/curl/actions/runs/13226709122/job/36921490162?pr=16278#step:8:3751

Follow-up to 6f5ff0e curl#7276

``` D:/a/curl/curl/CMake/CurlTests.c:155:12: warning: unused variable 'off_t_is_large' [-Wunused-variable] ```

…ixup 1 AmigaOS: ``` warning: excess elements in struct initializer ```

…ixup 1 cleanup

…inter target type [-Wdiscarded-qualifiers] (AmigaOS)

…edness [-Wpointer-sign]

… option" This reverts commit 856ee80.

``` conftest.c(38): error: #error directive: force compilation error #error force compilation error ^ conftest.c(40): warning curl#1011: missing return statement at end of non-void function "main" } ^ ```

MS-DOS: ``` /home/runner/work/curl/curl/CMake/CurlTests.c:324:25: warning: excess elements in struct initializer 324 | struct timespec ts = {0, 0}; | ^ ``` AmigaOS: ``` /home/runner/work/curl/curl/CMake/CurlTests.c:324:24: warning: missing braces around initializer [-Wmissing-braces] struct timespec ts = {0, 0}; ^ ```

This allows to avoid the unused variable warning when the struct is not available.

…t-variable]

This reverts commit 554a65a.

Silence compiler warnings (200 of them across the main CI workflows): ``` warning #2193: null argument provided for parameter marked with attribute "nonnull" warning: Null pointer passed to 1st parameter expecting 'nonnull' [core.NonNullParamChecker] warning: Null pointer passed to 2nd parameter expecting 'nonnull' [core.NonNullParamChecker] warning: argument 1 null where non-null expected [-Wnonnull] warning: argument 2 null where non-null expected [-Wnonnull] warning: comparison of unsigned expression in '< 0' is always false [-Wtype-limits] warning: null argument where non-null required (argument 1) [-Wnonnull] ``` Also drop `if ... can be linked` feature checks that were identical to `if ... is compilable` checks, for: `closesocket`, `ioctlsocket`, `socket`, `freeaddrinfo`, `getaddrinfo`, `gethostname`, `getpeername`, `getsockname`, `CloseSocket` (AmigaOS), `IoctlSocket` (AmigaOS). Another option is to really do the link checks. But, if they weren't missed so far, it seems safer to drop than risk a detection failure, as was the case with AmigaOS functions while working on this PR. There remain 22 `-Wnonnull` warnings in `gethostbyname_r()`, `getpeername()` `getsockname()`. Most of the rest is necessary for detection, or originate from autotools and CMake detection code templates. Some still fixable, like duplicate libs. Follow-up to ca2f49d #16287 Closes #16377

A deprecation error prevented correct detection in MSVC UWP builds: ``` curl\\bld\\CMakeFiles\\CMakeScratch\\TryCompile-ks2aa4\\CheckSymbolExists.c(8,19): error C4996: 'SSL_CTX_set_srp_username': Since OpenSSL 3.0 ``` Ref: https://github.com/curl/curl/actions/runs/13242285473/job/36960223663#step:8:898 It seems to be caused by different default warning levels used by the toolchain (or CMake?): `/W3` for UWP and `/W1` for Windows desktop. https://github.com/curl/curl/actions/runs/13242285473/job/36960223663#step:8:893 UWP https://github.com/curl/curl/actions/runs/13242285473/job/36960223262#step:8:445 desktop Fix by passing the OpenSSL macro suppressing its deprecation warnings. Cherry-picked from curl#16287 Closes curl#16293

Fix or silence compiler warnings happening in feature detections to reduce log noise. Warnings may also get promoted to errors in certain cases, causing missed detections. It reduces the number of warnings by 4500+ across the linux, linux-old, macos, non-native and windows GHA workflows (~142 jobs). Also move picky warning logic for MSVC/Borland to `CMake/PickyWarnings.cmake. To make them listed in the picky-warnings log output, and to also apply to feature detections to make them compile under the same conditions as source code. The hope is to help catching issues faster. It also improves code quality of feature tests. Fixed/silenced: ``` warning curl#177: variable "dummy" was declared but never referenced warning curl#177: variable "flag" was declared but never referenced warning curl#177: variable "res" was declared but never referenced warning curl#592: variable "s" is used before its value is set warning curl#1011: missing return statement at end of non-void function "main" warning curl#1786: function "SSL_CTX_set_srp_password" (declared at line 1888 of "/usr/include/openssl/ssl.h") was declared deprecated ("Since OpenSSL 3.0") warning curl#1786: function "SSL_CTX_set_srp_username" (declared at line 1887 of "/usr/include/openssl/ssl.h") was declared deprecated ("Since OpenSSL 3.0") warning curl#2332: a value of type "const char *" cannot be assigned to an entity of type "char *" (dropping qualifiers) warning: 'SSL_CTX_set_srp_password' is deprecated [-Wdeprecated-declarations] warning: 'SSL_CTX_set_srp_password' is deprecated: Since OpenSSL 3.0 [-Wdeprecated-declarations] warning: 'SSL_CTX_set_srp_username' is deprecated [-Wdeprecated-declarations] warning: 'SSL_CTX_set_srp_username' is deprecated: Since OpenSSL 3.0 [-Wdeprecated-declarations] warning: 'b' is used uninitialized [-Wuninitialized] warning: 'gethostname' redeclared without dllimport attribute: previous dllimport ignored [-Wattributes] warning: Undefined or garbage value returned to caller [core.uninitialized.UndefReturn] warning: Value stored to 'i' is never read [deadcode.DeadStores] warning: assigning to 'char *' from 'const char *' discards qualifiers [-Wincompatible-pointer-types-discards-qualifiers] warning: assignment discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers] warning: control reaches end of non-void function [-Wreturn-type] warning: empty expression statement has no effect; remove unnecessary ';' to silence this warning [-Wextra-semi-stmt] warning: excess elements in struct initializer warning: initialization discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers] warning: macro "_FILE_OFFSET_BITS" is not used [-Wunused-macros] warning: macro "_REENTRANT" is not used [-Wunused-macros] warning: missing braces around initializer [-Wmissing-braces] warning: no previous extern declaration for non-static variable 'off_t_is_large' [-Wmissing-variable-declarations] warning: no previous prototype for 'check' [-Wmissing-prototypes] warning: no previous prototype for function 'check' [-Wmissing-prototypes] warning: null argument where non-null required (argument 2) [-Wnonnull] warning: passing 'const char[1]' to parameter of type 'char *' discards qualifiers [-Wincompatible-pointer-types-discards-qualifiers] warning: passing argument 2 of 'SSL_CTX_set_srp_password' discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers] warning: passing argument 2 of 'SSL_CTX_set_srp_username' discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers] warning: unused parameter 'c' [-Wunused-parameter] warning: unused parameter 'f' [-Wunused-parameter] warning: unused variable 'data' [-Wunused-variable] warning: unused variable 'dummy' [-Wunused-variable] warning: unused variable 'flag' [-Wunused-variable] warning: unused variable 'res' [-Wunused-variable] warning: unused variable 's' [-Wunused-variable] warning: variable 's' set but not used [-Wunused-but-set-variable] warning: variable 'ts' set but not used [-Wunused-but-set-variable] ``` Closes curl#16287

Silence compiler warnings (200 of them across the main CI workflows): ``` warning curl#2193: null argument provided for parameter marked with attribute "nonnull" warning: Null pointer passed to 1st parameter expecting 'nonnull' [core.NonNullParamChecker] warning: Null pointer passed to 2nd parameter expecting 'nonnull' [core.NonNullParamChecker] warning: argument 1 null where non-null expected [-Wnonnull] warning: argument 2 null where non-null expected [-Wnonnull] warning: comparison of unsigned expression in '< 0' is always false [-Wtype-limits] warning: null argument where non-null required (argument 1) [-Wnonnull] ``` Also drop `if ... can be linked` feature checks that were identical to `if ... is compilable` checks, for: `closesocket`, `ioctlsocket`, `socket`, `freeaddrinfo`, `getaddrinfo`, `gethostname`, `getpeername`, `getsockname`, `CloseSocket` (AmigaOS), `IoctlSocket` (AmigaOS). Another option is to really do the link checks. But, if they weren't missed so far, it seems safer to drop than risk a detection failure, as was the case with AmigaOS functions while working on this PR. There remain 22 `-Wnonnull` warnings in `gethostbyname_r()`, `getpeername()` `getsockname()`. Most of the rest is necessary for detection, or originate from autotools and CMake detection code templates. Some still fixable, like duplicate libs. Follow-up to ca2f49d curl#16287 Closes curl#16377

vszakats added build tidy-up labels Feb 10, 2025

This was referenced Feb 10, 2025

tidy-up: delete, comment or scope C macros reported unused #16279

Closed

cmake: fix to detect HAVE_OPENSSL_SRP in MSVC UWP builds #16293

Closed

vszakats force-pushed the b-detwarn-2 branch from 069b2ef to 95e7eff Compare February 11, 2025 02:38

vszakats force-pushed the b-detwarn-2 branch from 95e7eff to 6e53c61 Compare February 11, 2025 13:19

vszakats marked this pull request as draft February 11, 2025 22:39

vszakats force-pushed the b-detwarn-2 branch from a22a048 to dde1a7d Compare February 12, 2025 21:06

vszakats marked this pull request as ready for review February 13, 2025 14:55

vszakats force-pushed the b-detwarn-2 branch 3 times, most recently from 32ea31a to a81bb2d Compare February 15, 2025 10:50

vszakats added 17 commits February 16, 2025 02:07

CMakeLists.txt: replace comment with if condition for -Werror option

e2e5ccd

whitespace

3032b02

CurlTests.c: fix more unused variable warnings

a11df80

CurlTests.c: delete unused variables

707cb16

Follow-up to 6f5ff0e curl#7276

CurlTests.c: fix more unused variable warnings 2

5458c56

indent

423a744

indent more

6a97c48

CurlTests.c: fix unused variable warning (clang)

91b54fc

``` D:/a/curl/curl/CMake/CurlTests.c:155:12: warning: unused variable 'off_t_is_large' [-Wunused-variable] ```

configure: silence compiler warnings in feature detection code

60d88fe

vszakats added 21 commits February 16, 2025 02:08

sockaddr_in6 restore (void)s, try silencing Intel C differently try f…

a8712e1

…ixup 1 AmigaOS: ``` warning: excess elements in struct initializer ```

sockaddr_in6 restore (void)s, try silencing Intel C differently try f…

200cef1

…ixup 1 cleanup

try another way 1

7e6d146

try fixing warning: initialization discards 'const' qualifier from po…

24d6d8f

…inter target type [-Wdiscarded-qualifiers] (AmigaOS)

silence new warning: pointer targets in initialization differ in sign…

3c8a9c5

…edness [-Wpointer-sign]

try another way 1 revert

8cbf3aa

try revert/fixup

8f716fc

Revert "CMakeLists.txt: replace comment with if condition for -Werror…

40d75aa

… option" This reverts commit 856ee80.

sync call cast with others

530b047

sync with configure to avoid Intel C warning

e13aa90

``` conftest.c(38): error: #error directive: force compilation error #error force compilation error ^ conftest.c(40): warning curl#1011: missing return statement at end of non-void function "main" } ^ ```

fix one more potential missing "return" case

53951b0

indentation

a6ff5cf

ws

8541fc8

more cases of set but not used variables

28d22f1

revert adding a return that was not silencing any warning

8bca49a

use sizeof() method to detect presence of struct

0bd0a5c

This allows to avoid the unused variable warning when the struct is not available.

try silencing warning: variable 's' set but not used [-Wunused-but-se…

2dd582f

…t-variable]

strcasecmp: pass non-NULL arguments, to avoid nonnull warnings

2ff2217

pass more non-NULL const arguments, to avoid nonnull warnings

fbb24fe

Revert "do not precache (temp)"

65140bd

This reverts commit 554a65a.

vszakats force-pushed the b-detwarn-2 branch from a81bb2d to 65140bd Compare February 16, 2025 01:08

vszakats closed this in ca2f49d Feb 16, 2025

vszakats deleted the b-detwarn-2 branch February 16, 2025 01:41

vszakats mentioned this pull request Feb 18, 2025

configure: silence compiler warnings in feature checks, drop duplicates #16377

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build: fix compiler warnings in feature detections#16287

build: fix compiler warnings in feature detections#16287
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