cmd/go: error: pointer is missing a nullability type specifier when building on catalina

[Tochemey]

What version of Go are you using (go version)?

$ go version
go version go1.13.3 darwin/amd64

Does this issue reproduce with the latest release?

What operating system and processor architecture are you using (go env)?

go env Output

$ go env
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/arsenegandote/Library/Caches/go-build"
GOENV="/Users/arsenegandote/Library/Application Support/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GONOPROXY=""
GONOSUMDB=""
GOOS="darwin"
GOPATH="/Users/arsenegandote/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/Cellar/go/1.13.3/libexec"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/Cellar/go/1.13.3/libexec/pkg/tool/darwin_amd64"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/_9/v2g8jyjj051bj38hln17lchw0000gn/T/go-build584306134=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

go test -mod=vendor

What did you expect to see?

At least the test should run

What did you see instead?

runtime/cgo

In file included from _cgo_export.c:3:
/usr/local/include/stdlib.h:134:25: error: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Werror,-Wnullability-completeness]
/usr/local/include/stdlib.h:134:25: note: insert '_Nullable' if the pointer may be null
/usr/local/include/stdlib.h:134:25: note: insert '_Nonnull' if the pointer should never be null
/usr/local/include/stdlib.h:135:22: error: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Werror,-Wnullability-completeness]
/usr/local/include/stdlib.h:135:22: note: insert '_Nullable' if the pointer may be null
/usr/local/include/stdlib.h:135:22: note: insert '_Nonnull' if the pointer should never be null
/usr/local/include/stdlib.h:136:23: error: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Werror,-Wnullability-completeness]
/usr/local/include/stdlib.h:136:23: note: insert '_Nullable' if the pointer may be null
/usr/local/include/stdlib.h:136:23: note: insert '_Nonnull' if the pointer should never be null
/usr/local/include/stdlib.h:139:20: error: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Werror,-Wnullability-completeness]
/usr/local/include/stdlib.h:139:20: note: insert '_Nullable' if the pointer may be null
/usr/local/include/stdlib.h:139:20: note: insert '_Nonnull' if the pointer should never be null
/usr/local/include/stdlib.h:141:26: error: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Werror,-Wnullability-completeness]
/usr/local/include/stdlib.h:141:26: note: insert '_Nullable' if the pointer may be null
/usr/local/include/stdlib.h:141:26: note: insert '_Nonnull' if the pointer should never be null
/usr/local/include/stdlib.h:141:45: error: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Werror,-Wnullability-completeness]
/usr/local/include/stdlib.h:141:45: note: insert '_Nullable' if the pointer may be null
/usr/local/include/stdlib.h:141:45: note: insert '_Nonnull' if the pointer should never be null
/usr/local/include/stdlib.h:142:59: error: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Werror,-Wnullability-completeness]
/usr/local/include/stdlib.h:142:59: note: insert '_Nullable' if the pointer may be null
/usr/local/include/stdlib.h:142:59: note: insert '_Nonnull' if the pointer should never be null
/usr/local/include/stdlib.h:142:73: error: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Werror,-Wnullability-completeness]
/usr/local/include/stdlib.h:142:73: note: insert '_Nullable' if the pointer may be null
/usr/local/include/stdlib.h:142:73: note: insert '_Nonnull' if the pointer should never be null
/usr/local/include/stdlib.h:141:6: error: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Werror,-Wnullability-completeness]
/usr/local/include/stdlib.h:141:6: note: insert '_Nullable' if the pointer may be null
/usr/local/include/stdlib.h:141:6: note: insert '_Nonnull' if the pointer should never be null
/usr/local/include/stdlib.h:147:25: error: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Werror,-Wnullability-completeness]
/usr/local/include/stdlib.h:147:25: note: insert '_Nullable' if the pointer may be null
/usr/local/include/stdlib.h:147:25: note: insert '_Nonnull' if the pointer should never be null
/usr/local/include/stdlib.h:147:6: error: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Werror,-Wnullability-completeness]
/usr/local/include/stdlib.h:147:6: note: insert '_Nullable' if the pointer may be null
/usr/local/include/stdlib.h:147:6: note: insert '_Nonnull' if the pointer should never be null
/usr/local/include/stdlib.h:156:23: error: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Werror,-Wnullability-completeness]
/usr/local/include/stdlib.h:156:23: note: insert '_Nullable' if the pointer may be null
/usr/local/include/stdlib.h:156:23: note: insert '_Nonnull' if the pointer should never be null
/usr/local/include/stdlib.h:157:26: error: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Werror,-Wnullability-completeness]
/usr/local/include/stdlib.h:157:26: note: insert '_Nullable' if the pointer may be null
/usr/local/include/stdlib.h:157:26: note: insert '_Nonnull' if the pointer should never be null
/usr/local/include/stdlib.h:157:52: error: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Werror,-Wnullability-completeness]
/usr/local/include/stdlib.h:157:52: note: insert '_Nullable' if the pointer may be null
/usr/local/include/stdlib.h:157:52: note: insert '_Nonnull' if the pointer should never be null
/usr/local/include/stdlib.h:158:21: error: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Werror,-Wnullability-completeness]
/usr/local/include/stdlib.h:158:21: note: insert '_Nullable' if the pointer may be null
/usr/local/include/stdlib.h:158:21: note: insert '_Nonnull' if the pointer should never be null
/usr/local/include/stdlib.h:158:46: error: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Werror,-Wnullability-completeness]
/usr/local/include/stdlib.h:158:46: note: insert '_Nullable' if the pointer may be null
/usr/local/include/stdlib.h:158:46: note: insert '_Nonnull' if the pointer should never be null
/usr/local/include/stdlib.h:160:18: error: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Werror,-Wnullability-completeness]
/usr/local/include/stdlib.h:160:18: note: insert '_Nullable' if the pointer may be null
/usr/local/include/stdlib.h:160:18: note: insert '_Nonnull' if the pointer should never be null
/usr/local/include/stdlib.h:161:43: error: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Werror,-Wnullability-completeness]
/usr/local/include/stdlib.h:161:43: note: insert '_Nullable' if the pointer may be null
/usr/local/include/stdlib.h:161:43: note: insert '_Nonnull' if the pointer should never be null
/usr/local/include/stdlib.h:161:57: error: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Werror,-Wnullability-completeness]
/usr/local/include/stdlib.h:161:57: note: insert '_Nullable' if the pointer may be null
/usr/local/include/stdlib.h:161:57: note: insert '_Nonnull' if the pointer should never be null
fatal error: too many errors emitted, stopping now [-ferror-limit=]

Compilation finished with exit code 2

[ianlancetaylor]

Has clang really decided to enable the -Wnullability-completeness warning by default, as suggested by https://bcain-llvm.readthedocs.io/projects/clang/en/latest/DiagnosticsReference/#wnullability-completeness ? That seems designed to break all existing code. I must be missing something.

[ianlancetaylor]

Note that these warnings are for /usr/local/include/stdlib.h, which does not come from Go. Is that the version of stdlib.h that corresponds to the C compiler that you are using?

[Tochemey]

@ianlancetaylor I cannot really tell. I just did an upgrade to catalina and installed golang. So when I try to build I got the error. During the installation I did not get any errors that could have given a hint.

[ianlancetaylor]

Unless someone else is seeing this problem on catalina, I suspect this is a problem with the installation on your system.

[ianlancetaylor]

Sorry, I mean a problem with the XCode installation. I don't see a reason to think that there is anything wrong with the Go installation.

[42yeah]

Had the same problem. Upgraded to catalina and this appears:

# runtime/cgo
In file included from _cgo_export.c:3:
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/stdlib.h:134:25: error: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Werror,-Wnullability-completeness]
...

Also tried using clang to compile some random source including stdlib.h, and it did it gave out bunches of warnings almost identical to the above, however those weren't error, only warnings:

❯ clang a.c
In file included from a.c:1:
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/stdlib.h:134:25: warning: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Wnullability-completeness]
double   atof(const char *);
...

[dust347]

I also have same problem after upgrade to catalina

export CGO_CPPFLAGS="-Wno-error -Wno-nullability-completeness -Wno-expansion-to-defined"

Maybe it can be solved

[ianlancetaylor]

I don't understand how XCode could possibly be shipping a <stdlib.h> that cannot be compiled without warnings in the default compiler setting. Can somebody investigate that? What happens if you simply compile the C program

#include <stdlib.h>

? Do you get warnings?

[yiyanwannian]

Encounter same issue

[ianlancetaylor]

@yiyanwannian Please see my question in #35247 (comment) which has not yet been answered. Thanks.

[42yeah]

@ianlancetaylor Please see my comment above. And here's the content of a.c:

#include <stdlib.h>

int main() {

  return 0;
}

It has the same problem when being compiled, however those were only warnings. When in cgo, those became errors.

[ianlancetaylor]

I'm sorry, somehow I missed that comment.

If clang is emitting a lot of warnings for code that simply includes <stdlib.h>, I can't help but feel that that is a problem with the installation.

I see this issue raised for C code on Stack Overflow at https://stackoverflow.com/questions/58429844/c-multiple-warnings-pointer-is-missing-a-nullability-type-specifier-when-com .

This just seems to me like something that Apple has to fix.

In the meantime see if https://golang.org/cl/205457 fixes the problems.

[bradfitz]

A Catalina builder would've caught this (#34748).

[gopherbot]

Change https://golang.org/cl/205457 mentions this issue: runtime/cgo: add -Wno-nullability-completeness on Darwin

[daravi]

If clang is emitting a lot of warnings for code that simply includes <stdlib.h>, I can't help but feel that that is a problem with the installation.

For what it's worth I don't see the issue with XCode 11.3 on Mojave using system's clang, but do get it if I use my clang built from source.

[bigemon]

I also have same problem after upgrade to catalina

export CGO_CPPFLAGS="-Wno-error -Wno-nullability-completeness -Wno-expansion-to-defined"

Maybe it can be solved

you saved my day, thanks :)

[felixge]

I just upgraded to Catalina and also had issues with clang throwing warnings.

Turns out this was caused by having installed clang via homebrew. brew remove llvm fixed the issue.

So perhaps https://go-review.googlesource.com/c/go/+/205457/ is only needed to support users who have installed their own version of clang?

[matiasinsaurralde]

I'm facing the same issue 😞

[davecheney]

@matiasinsaurralde this issue is closed. If the problem occurs for you with the latest version of Go please open a new issue including all the information someone who does not have access to your environment will need to reproduce the problem.

[gopherbot]

Change https://golang.org/cl/368634 mentions this issue: runtime/cgo: remove stdlib.h warning workaround on darwin

[bcmills]

The Clang documentation for -Wnullability-completeness gives its error text but not its actual semantics.

From the doc comment for the actual implementation in the compiler, the warning enabled by the flag actually:

Complains about missing nullability if the file … has other uses of nullability (either the keywords or the assume_nonnull pragma).

So this is indeed a configuration problem, caused by mixing a clang with strict nullability checks with a stdlib.h (and its transitively-included headers) that contains a mix of annotated and unannotated pointers.

That seems to jibe with the theory in #35247 (comment) that this may be caused by mixing a Homebrew clang with an XCode stdlib.h, or perhaps by mixing Homebrew and XCode headers for dependencies of stdlib.h.

[bcmills]

As as interesting data point, CL 368634 removes the -Wno-nullability-completeness workaround and passes on all of the Go project's Cgo-enabled macOS builders.