Add govet linter with fieldalignment

[pellared]

Why

govet's fieldalignment analyzer helps to reduce the memory footprint

Slack thread

Here is what the analyzer detected for the production code:

golangci-lint in .
attribute/iterator.go:33:18: fieldalignment: struct with 88 pointer bytes could be 72 (govet)
type oneIterator struct {
                 ^
attribute/kv.go:24:15: fieldalignment: struct with 64 pointer bytes could be 56 (govet)
type KeyValue struct {
              ^
attribute/value.go:32:12: fieldalignment: struct with 48 pointer bytes could be 24 (govet)
type Value struct {
           ^
attribute/value.go:197:14: fieldalignment: struct with 32 pointer bytes could be 24 (govet)
        var jsonVal struct {
                    ^
internal/global/propagator.go:27:24: fieldalignment: struct with 56 pointer bytes could be 32 (govet)
type textMapPropagator struct {
                       ^
internal/global/trace.go:48:21: fieldalignment: struct with 32 pointer bytes could be 24 (govet)
type tracerProvider struct {
                    ^
internal/global/trace.go:120:13: fieldalignment: struct with 56 pointer bytes could be 40 (govet)
type tracer struct {
            ^
golangci-lint in ./bridge/opencensus
aggregation.go:150:23: fieldalignment: struct with 88 pointer bytes could be 56 (govet)
type ocDistAggregator struct {
                      ^
exporter.go:56:20: fieldalignment: struct with 32 pointer bytes could be 8 (govet)
type checkpointSet struct {
                   ^
golangci-lint in ./bridge/opentracing
bridge.go:82:17: fieldalignment: struct with 48 pointer bytes could be 40 (govet)
type bridgeSpan struct {
                ^
bridge.go:280:22: fieldalignment: struct of size 48 could be 40 (govet)
type bridgeSetTracer struct {
                     ^
bridge.go:304:19: fieldalignment: struct with 88 pointer bytes could be 56 (govet)
type BridgeTracer struct {
                  ^
golangci-lint in ./exporters/metric/prometheus
prometheus.go:41:15: fieldalignment: struct with 88 pointer bytes could be 64 (govet)
type Exporter struct {
              ^
golangci-lint in ./exporters/otlp
otlphttp/driver.go:66:13: fieldalignment: struct with 1088 pointer bytes could be 1040 (govet)
type driver struct {
            ^
otlphttp/driver.go:74:19: fieldalignment: struct with 400 pointer bytes could be 352 (govet)
type signalDriver struct {
                  ^
internal/transform/metric.go:62:13: fieldalignment: struct with 80 pointer bytes could be 72 (govet)
type result struct {
            ^
otlpgrpc/connection.go:40:17: fieldalignment: struct with 440 pointer bytes could be 384 (govet)
type connection struct {
                ^
otlpgrpc/driver.go:42:20: fieldalignment: struct with 32 pointer bytes could be 24 (govet)
type metricsDriver struct {
                   ^
otlpgrpc/driver.go:49:19: fieldalignment: struct with 32 pointer bytes could be 24 (govet)
type tracesDriver struct {
                  ^
internal/otlpconfig/options.go:58:15: fieldalignment: struct with 88 pointer bytes could be 56 (govet)
        SignalConfig struct {
                     ^
internal/otlpconfig/options.go:71:9: fieldalignment: struct with 232 pointer bytes could be 200 (govet)
        Config struct {
               ^
golangci-lint in ./exporters/otlp/otlptrace
internal/connection/connection.go:39:17: fieldalignment: struct with 344 pointer bytes could be 288 (govet)
type Connection struct {
                ^
internal/otlpconfig/options.go:53:15: fieldalignment: struct with 88 pointer bytes could be 56 (govet)
        SignalConfig struct {
                     ^
internal/otlpconfig/options.go:66:9: fieldalignment: struct with 136 pointer bytes could be 112 (govet)
        Config struct {
               ^
golangci-lint in ./exporters/otlp/otlptrace/otlptracegrpc
client.go:34:13: fieldalignment: struct with 32 pointer bytes could be 24 (govet)
type client struct {
            ^
golangci-lint in ./exporters/otlp/otlptrace/otlptracehttp
client.go:61:13: fieldalignment: struct with 304 pointer bytes could be 256 (govet)
type client struct {
            ^
golangci-lint in ./exporters/stdout
config.go:34:13: fieldalignment: struct of size 48 could be 40 (govet)
type config struct {
            ^
exporter.go:22:15: fieldalignment: struct with 120 pointer bytes could be 88 (govet)
type Exporter struct {
              ^
metric.go:36:11: fieldalignment: struct with 104 pointer bytes could be 96 (govet)
type line struct {
          ^
golangci-lint in ./exporters/trace/jaeger
agent.go:36:21: fieldalignment: struct with 88 pointer bytes could be 80 (govet)
type agentClientUDP struct {
                    ^
agent.go:53:27: fieldalignment: struct with 48 pointer bytes could be 32 (govet)
type agentClientUDPParams struct {
                          ^
jaeger.go:72:15: fieldalignment: struct with 48 pointer bytes could be 32 (govet)
type Exporter struct {
              ^
reconnecting_udp_client.go:28:26: fieldalignment: struct with 96 pointer bytes could be 56 (govet)
type reconnectingUDPConn struct {
                         ^
uploader.go:176:30: fieldalignment: struct with 56 pointer bytes could be 48 (govet)
type collectorEndpointConfig struct {
                             ^
uploader.go:264:24: fieldalignment: struct with 56 pointer bytes could be 48 (govet)
type collectorUploader struct {
                       ^
golangci-lint in ./exporters/trace/zipkin
zipkin_test.go:78:26: fieldalignment: struct with 80 pointer bytes could be 48 (govet)
type mockZipkinCollector struct {
                         ^
golangci-lint in ./internal/metric
async.go:42:27: fieldalignment: struct with 64 pointer bytes could be 40 (govet)
type AsyncInstrumentState struct {
                          ^
global/meter.go:54:20: fieldalignment: struct with 32 pointer bytes could be 24 (govet)
type meterProvider struct {
                   ^
global/meter.go:65:16: fieldalignment: struct with 48 pointer bytes could be 40 (govet)
type meterImpl struct {
               ^
global/meter.go:88:16: fieldalignment: struct with 112 pointer bytes could be 104 (govet)
type asyncImpl struct {
               ^
golangci-lint in ./metric
registry/registry.go:36:32: fieldalignment: struct with 32 pointer bytes could be 24 (govet)
type uniqueInstrumentMeterImpl struct {
                               ^
metric.go:522:17: fieldalignment: struct with 80 pointer bytes could be 72 (govet)
type Descriptor struct {
                ^
metric_instrument.go:96:18: fieldalignment: struct with 24 pointer bytes could be 16 (govet)
type Observation struct {
                 ^
metric_instrument.go:280:20: fieldalignment: struct with 64 pointer bytes could be 56 (govet)
type BatchObserver struct {
                   ^
metric_instrument.go:390:18: fieldalignment: struct with 24 pointer bytes could be 16 (govet)
type Measurement struct {
                 ^
metrictest/meter.go:35:8: fieldalignment: struct with 72 pointer bytes could be 64 (govet)
        Batch struct {
              ^
metrictest/meter.go:44:12: fieldalignment: struct with 40 pointer bytes could be 16 (govet)
        MeterImpl struct {
                  ^
metrictest/meter.go:52:14: fieldalignment: struct with 24 pointer bytes could be 16 (govet)
        Measurement struct {
                    ^
metrictest/meter.go:63:8: fieldalignment: struct with 112 pointer bytes could be 104 (govet)
        Async struct {
              ^
metrictest/meter.go:198:15: fieldalignment: struct with 56 pointer bytes could be 48 (govet)
type Measured struct {
              ^
golangci-lint in ./oteltest
config.go:99:19: fieldalignment: struct with 80 pointer bytes could be 32 (govet)
type SpanRecorder struct {
                  ^
event.go:24:12: fieldalignment: struct with 48 pointer bytes could be 40 (govet)
type Event struct {
           ^
provider.go:27:21: fieldalignment: struct with 32 pointer bytes could be 24 (govet)
type TracerProvider struct {
                    ^
span.go:32:11: fieldalignment: struct of size 264 could be 256 (govet)
type Span struct {
          ^
text_map_propagator.go:32:21: fieldalignment: struct with 64 pointer bytes could be 40 (govet)
type TextMapCarrier struct {
                    ^
tracer.go:28:13: fieldalignment: struct with 40 pointer bytes could be 32 (govet)
type Tracer struct {
            ^
golangci-lint in ./sdk
trace/batch_span_processor.go:68:25: fieldalignment: struct with 144 pointer bytes could be 48 (govet)
type batchSpanProcessor struct {
                        ^
trace/event.go:24:12: fieldalignment: struct with 72 pointer bytes could be 48 (govet)
type Event struct {
           ^
trace/id_generator.go:33:24: fieldalignment: struct with 16 pointer bytes could be 8 (govet)
type randomIDGenerator struct {
                       ^
trace/provider.go:35:27: fieldalignment: struct with 104 pointer bytes could be 48 (govet)
type tracerProviderConfig struct {
                          ^
trace/provider.go:56:21: fieldalignment: struct with 112 pointer bytes could be 64 (govet)
type TracerProvider struct {
                    ^
trace/sampling.go:33:25: fieldalignment: struct with 88 pointer bytes could be 64 (govet)
type SamplingParameters struct {
                        ^
trace/sampling.go:60:21: fieldalignment: struct with 40 pointer bytes could be 32 (govet)
type SamplingResult struct {
                    ^
trace/sampling.go:66:26: fieldalignment: struct with 16 pointer bytes could be 8 (govet)
type traceIDRatioSampler struct {
                         ^
trace/simple_span_processor.go:26:26: fieldalignment: struct with 40 pointer bytes could be 16 (govet)
type simpleSpanProcessor struct {
                         ^
trace/snapshot.go:28:15: fieldalignment: struct with 376 pointer bytes could be 320 (govet)
type snapshot struct {
              ^
trace/span.go:98:11: fieldalignment: struct with 336 pointer bytes could be 288 (govet)
type span struct {
          ^
trace/span.go:625:13: fieldalignment: struct with 16 pointer bytes could be 8 (govet)
type Status struct {
            ^
trace/trace_test.go:163:18: fieldalignment: struct with 32 pointer bytes could be 16 (govet)
type testSampler struct {
                 ^
trace/tracetest/span.go:57:15: fieldalignment: struct with 376 pointer bytes could be 320 (govet)
type SpanStub struct {
              ^
trace/tracetest/span.go:124:19: fieldalignment: struct with 392 pointer bytes could be 336 (govet)
type spanSnapshot struct {
                  ^
resource/builtin.go:43:17: fieldalignment: struct with 40 pointer bytes could be 32 (govet)
        stringDetector struct {
                       ^
resource/config.go:24:13: fieldalignment: struct with 32 pointer bytes could be 24 (govet)
type config struct {
            ^
golangci-lint in ./sdk/export/metric
metrictest/test.go:39:20: fieldalignment: struct with 64 pointer bytes could be 24 (govet)
type CheckpointSet struct {
                   ^
aggregation/aggregation.go:78:8: fieldalignment: struct with 32 pointer bytes could be 24 (govet)
        Point struct {
              ^
golangci-lint in ./sdk/metric
controller/basic/config.go:26:13: fieldalignment: struct with 40 pointer bytes could be 24 (govet)
type config struct {
            ^
controller/basic/controller.go:57:17: fieldalignment: struct with 160 pointer bytes could be 112 (govet)
type Controller struct {
                ^
sdk.go:44:14: fieldalignment: struct with 120 pointer bytes could be 80 (govet)
        Accumulator struct {
                    ^
sdk.go:87:9: fieldalignment: struct with 112 pointer bytes could be 72 (govet)
        record struct {
               ^
sdk.go:130:18: fieldalignment: struct with 104 pointer bytes could be 96 (govet)
        asyncInstrument struct {
                        ^
sdk.go:137:18: fieldalignment: struct with 32 pointer bytes could be 24 (govet)
        labeledRecorder struct {
                        ^
processor/basic/basic.go:55:13: fieldalignment: struct with 80 pointer bytes could be 64 (govet)
        stateValue struct {
                   ^
processor/basic/basic.go:95:8: fieldalignment: struct with 112 pointer bytes could be 80 (govet)
        state struct {
              ^
aggregator/exact/exact.go:32:13: fieldalignment: struct with 16 pointer bytes could be 8 (govet)
        Aggregator struct {
                   ^
aggregator/lastvalue/lastvalue.go:40:16: fieldalignment: struct with 32 pointer bytes could be 24 (govet)
        lastValueData struct {
                      ^
aggregator/histogram/histogram.go:37:13: fieldalignment: struct with 48 pointer bytes could be 16 (govet)
        Aggregator struct {
                   ^
golangci-lint in ./trace
config.go:139:18: fieldalignment: struct with 48 pointer bytes could be 32 (govet)
type EventConfig struct {
                 ^
trace.go:184:24: fieldalignment: struct of size 64 could be 56 (govet)
type SpanContextConfig struct {
                       ^
trace.go:205:18: fieldalignment: struct of size 64 could be 56 (govet)
type SpanContext struct {
                 ^
trace.go:393:11: fieldalignment: struct with 72 pointer bytes could be 64 (govet)
type Link struct {
          ^

What

• Add govet to golangci-lint configuration
• Change the lint target to ALWAYS run golangci-lint for all modules (instead of fail-fast)
• Fix or ignore issues reported in test code

TODO

• Fix issues reported in production code

[pellared]

The fieldalignment analyzer is very annoying.
Better explained here: atc0005/go-ci#302
I spend hours trying to satisfy the analyzer but I think it is not worth the effort...