add cc config info to dummy wasm32 cc toolchain

[kcking]

Fixes building with new cc toolchain resolution flag --incompatible_enable_cc_toolchain_resolution=1, which I am using in a project that involves a cross-compiled native rust web-server serving rust compiled to wasm.

[UebelAndre]

Thanks @kcking! Can you provide an stacktrace or example of the error you get without this change?

[kcking]

Sure thing, here's a more minimal repro of the issue: https://github.com/kcking/bazel-repro-1532

The stack trace is

Analyzing: target //:wasm-and-bin (196 packages loaded, 8245 targets configured)
FATAL: bazel crashed due to an internal error. Printing stack trace:
java.lang.RuntimeException: Unrecoverable error while evaluating node 'ConfiguredTargetKey{label=@bazel_tools//tools/cpp:current_cc_toolchain, config=BuildConfigurationValue.Key[92e5d91b302bd50add78c487b06a677a8c261db39969e92317ccc69c68cd948e]}' (requested by nodes 'ConfiguredTargetKey{label=//:bin, config=BuildConfigurationValue.Key[92e5d91b302bd50add78c487b06a677a8c261db39969e92317ccc69c68cd948e]}', 'ToolchainDependencyConfiguredTargetKey{label=@rust_darwin_aarch64__wasm32-unknown-unknown_tools//:rust_toolchain, config=BuildConfigurationValue.Key[92e5d91b302bd50add78c487b06a677a8c261db39969e92317ccc69c68cd948e], executionPlatformLabel=@local_config_platform//:host}')
        at com.google.devtools.build.skyframe.AbstractParallelEvaluator$Evaluate.run(AbstractParallelEvaluator.java:674)
        at com.google.devtools.build.lib.concurrent.AbstractQueueVisitor$WrappedRunnable.run(AbstractQueueVisitor.java:382)
        at java.base/java.util.concurrent.ForkJoinTask$RunnableExecuteAction.exec(ForkJoinTask.java:1426)
        at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:290)
        at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1020)
        at java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1656)
        at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1594)
        at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:183)
Caused by: java.lang.NullPointerException
        at com.google.devtools.build.lib.rules.cpp.CcToolchain.createMakeVariableProvider(CcToolchain.java:122)
        at com.google.devtools.build.lib.rules.cpp.CcToolchainAliasRule$CcToolchainAlias.create(CcToolchainAliasRule.java:78)
        at com.google.devtools.build.lib.rules.cpp.CcToolchainAliasRule$CcToolchainAlias.create(CcToolchainAliasRule.java:69)
        at com.google.devtools.build.lib.analysis.ConfiguredTargetFactory.createRule(ConfiguredTargetFactory.java:364)
        at com.google.devtools.build.lib.analysis.ConfiguredTargetFactory.createConfiguredTarget(ConfiguredTargetFactory.java:188)
        at com.google.devtools.build.lib.skyframe.SkyframeBuildView.createConfiguredTarget(SkyframeBuildView.java:1108)
        at com.google.devtools.build.lib.skyframe.ConfiguredTargetFunction.createConfiguredTarget(ConfiguredTargetFunction.java:980)
        at com.google.devtools.build.lib.skyframe.ConfiguredTargetFunction.compute(ConfiguredTargetFunction.java:368)
        at com.google.devtools.build.skyframe.AbstractParallelEvaluator$Evaluate.run(AbstractParallelEvaluator.java:590)
        ... 7 more

I noticed a related issue bazelbuild/bazel#15304 was closed, but independently rules_rust should be providing a well-formed cc toolchain config.

[UebelAndre]

Thank you so much!