How to Handle Excessive Warning Messages When Running `pecl install grpc`

Overwhelming Warning Messages Can Be a Nuisance

When running pecl install grpc, you might encounter an avalanche of warning messages like these:

#7 67.72 /tmp/pear/temp/grpc/src/core/lib/promise/detail/promise_factory.h:174:5: warning: 'always_inline' function might not be inlinable [-Wattributes]

#7 352.5 /tmp/pear/temp/grpc/src/core/lib/event_engine/forkable.h:61:34: warning: 'unused' attribute ignored [-Wattributes]

There can be hundreds of these warnings, flooding your logs. This has been especially problematic during deployment, where CI/CD pipelines would exceed log limits, causing errors and halting the process.

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The Root Cause

Searching for the warning messages online points to GCC, the GNU Compiler Collection.

It turns out these warnings are generated by the compiler when building gRPC's source code. Since the warnings originate from gRPC’s source code, it’s not feasible for users to fix the source code directly to suppress the warnings.

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The Solution

Fortunately, GCC provides several options to suppress warning messages, which you can pass to the compiler during the build process:

Warning Options in GCC Documentation

However, there’s no straightforward way to pass these options directly when running pecl install grpc. If you know of one, please let me know—I’ll celebrate with tears of joy! 🥹

So, what now?

The answer came to me from a StackOverflow thread: Instead of letting pecl install handle everything, you can break the process into smaller steps and pass the options during the compilation phase.

Reference: StackOverflow

Since gRPC is written in C++, we can use environment variables like CFLAGS and CXXFLAGS to specify options that suppress the warnings during compilation:

Gentoo Wiki on GCC Optimization

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Implementation

Let’s assume gRPC is being installed in a Dockerfile.

Before

RUN pecl install grpc

After

RUN pecl download grpc \
  && tar xzf $(ls grpc-*.tgz | head -n 1) \
  && cd $(ls -d grpc-*/ | head -n 1) \
  && phpize \
  && ./configure --with-php-config=/usr/local/bin/php-config \
  && make -e CFLAGS="-Wno-attributes -Wno-unused-parameter -Wno-deprecated-declarations -Wno-return-type" CXXFLAGS="-Wno-attributes -Wno-unused-parameter -Wno-deprecated-declarations -Wno-return-type" \
  && make install

The after commands mimic what pecl install does internally, but with more control. Breaking down the process revealed just how much pecl install handles behind the scenes—impressive!

The warnings appeared during the make phase, so I passed the suppression options via the CFLAGS and CXXFLAGS environment variables:

make -e CFLAGS="-Wno-attributes -Wno-unused-parameter -Wno-deprecated-declarations -Wno-return-type" CXXFLAGS="-Wno-attributes -Wno-unused-parameter -Wno-deprecated-declarations -Wno-return-type"

How to Identify Suppression Options

To determine which suppression options to use, look at the end of the warning messages. You’ll often see hints like [-Wattributes] or [-Wunused-parameter]. Add no to the beginning of these, e.g., -Wno-attributes or -Wno-unused-parameter, to suppress them.

For more details, refer to the official documentation:

Warning Options in GCC Documentation

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Conclusion

With this approach, I successfully escaped the swamp of gRPC warning messages. However, this didn’t fully resolve the CI/CD log limit issue, which I’ll address in a future post.

If this article helps even one person escape the gRPC warning message swamp, I’ll be delighted! 🙌