feat(tool): support passing .go files to otelc go build by amazingakai · Pull Request #483 · open-telemetry/opentelemetry-go-compile-instrumentation

amazingakai · 2026-05-10T13:27:56Z

Description

Support passing .go source files to otelc go build command

Motivation

Currently passing .go files to otelc go build fails, while this is supported by go build command.

Checklist

PR title follows conventional commits format
Code formatted: make format
Linters pass: make lint
Tests pass: make test
Tests added for new functionality
Tests follow testing guidelines
Documentation updated (if applicable)

codecov · 2026-05-10T13:29:16Z

Codecov Report

❌ Patch coverage is 61.25000% with 31 lines in your changes missing coverage. Please review.
✅ Project coverage is 63.70%. Comparing base (2c74fda) to head (88fe92e).

Files with missing lines	Patch %	Lines
tool/internal/setup/setup.go	55.38%	23 Missing and 6 partials ⚠️
tool/internal/pkgload/pkgload.go	86.66%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #483      +/-   ##
==========================================
- Coverage   63.70%   63.70%   -0.01%     
==========================================
  Files          62       62              
  Lines        4794     4854      +60     
==========================================
+ Hits         3054     3092      +38     
- Misses       1486     1503      +17     
- Partials      254      259       +5

Flag	Coverage Δ
tool	`63.70% <61.25%> (-0.01%)`	⬇️

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Copilot

Pull request overview

Adds support for passing .go source files directly to otelc go build, aligning otelc behavior more closely with go build when users build from an explicit file list (which creates the synthetic command-line-arguments package).

Changes:

Parse build targets into package patterns vs .go file targets and load packages accordingly.
Support file-target builds by accepting command-line-arguments packages and injecting otelc.runtime.go onto the go build command line.
Extend unit tests to cover file targets and the new target-splitting behavior.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

File	Description
tool/internal/setup/setup.go	Adds target splitting, file-target package loading/filtering, and runtime file injection for file-based builds.
tool/internal/setup/setup_test.go	Adds/updates tests for file targets, mixing targets, and default package loading.

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amazingakai · 2026-05-13T17:35:24Z

+	restArgs := args[1:]
+	if _, fileTargets, err2 := splitBuildTargets(restArgs); err2 == nil && len(fileTargets) > 0 {
+		// add otelc.runtime.go manually to command line for file targets
+		dir := filepath.Dir(fileTargets[0])
+		otelcRuntimePath := filepath.Join(dir, OtelcRuntimeFile)
+		restArgs = append(restArgs, otelcRuntimePath)


This is not really true, If user does:
go build -C cmd main.go
It would do:
go build -C cmd main.go otelc.runtime.go
Similarly for:
go build -C cmd /home/.../absolute_path_to/main.go
It would do:
go build -C cmd /home/.../absolute_path_to/main.go cmd /home/.../absolute_path_to/otelc.runtime.go
In both cases, it should be correct, unless I'm missing something.

-C wasn't supported before. LoadPackages never sets Dir for packages.Config. I've created an issue for tackling this #507

txabman42 · 2026-05-15T18:16:33Z

+	restArgs := args[1:]
+	if _, fileTargets, err2 := splitBuildTargets(restArgs); err2 == nil && len(fileTargets) > 0 {
+		// add otelc.runtime.go manually to command line for file targets
+		dir := filepath.Dir(fileTargets[0])
+		otelcRuntimePath := filepath.Join(dir, OtelcRuntimeFile)
+		restArgs = append(restArgs, otelcRuntimePath)


-C wasn't supported before. LoadPackages never sets Dir for packages.Config. I've created an issue for tackling this #507

amazingakai · 2026-05-15T18:22:57Z

Thank you for the review, I will try to address the comments soon

amazingakai · 2026-05-18T11:56:50Z

This PR is ready for review again @y1yang0 @txabman42

I also don't think there is a performance regression here (or at least I don't see a reason for there to be). Not sure why the Windows integration tests are timing out.

Benchmark results on my local machine look effectively unchanged:

Before:

overhead_test.go:67: baseline: plain=4.116s  otelc=5.151s  overhead=+25.2%
overhead_test.go:67: largeidle: plain=13.270s  otelc=14.614s  overhead=+10.1%
overhead_test.go:67: multi: plain=16.276s  otelc=24.962s  overhead=+53.4%

After:

overhead_test.go:67: baseline: plain=4.095s  otelc=5.182s  overhead=+26.5%
overhead_test.go:67: largeidle: plain=13.200s  otelc=14.697s  overhead=+11.3%
overhead_test.go:67: multi: plain=16.301s  otelc=24.945s  overhead=+53.0%

txabman42 · 2026-05-18T21:20:52Z

@amazingakai

Not sure why the Windows integration tests are timing out.

Rerun just fixed it. Seems that runner was slow, probably bad neighbours.

txabman42

LGTM! Just some nitpicks

amazingakai · 2026-05-19T06:37:32Z

Done. Thank you for the review ❤️

kakkoyun

LGTM

kakkoyun · 2026-05-19T11:43:23Z

@amazingakai This needs a rebase.

amazingakai · 2026-05-19T15:51:56Z

@kakkoyun Done.

amazingakai requested a review from a team as a code owner May 10, 2026 13:27

github-actions Bot added the scope:feat A new feature being added label May 10, 2026

y1yang0 requested a review from Copilot May 13, 2026 12:56

Copilot started reviewing on behalf of y1yang0 May 13, 2026 12:56 View session

Copilot AI reviewed May 13, 2026

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y1yang0 reviewed May 13, 2026

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Comment thread tool/internal/setup/setup.go

amazingakai mentioned this pull request May 14, 2026

isSetup - Check if setup phase is already done(because we can either otel setup + otel go build or just otel go build) #161

Open

txabman42 requested changes May 15, 2026

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amazingakai force-pushed the support-go-files branch 2 times, most recently from 53e16f3 to 577b856 Compare May 18, 2026 11:05

txabman42 approved these changes May 18, 2026

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Comment thread tool/internal/setup/setup.go Outdated

Comment thread tool/internal/setup/setup.go

amazingakai force-pushed the support-go-files branch from 577b856 to a6ce8f6 Compare May 19, 2026 06:23

txabman42 requested a review from a team May 19, 2026 08:48

kakkoyun approved these changes May 19, 2026

View reviewed changes

kakkoyun requested a review from y1yang0 May 19, 2026 09:02

amazingakai added 6 commits May 19, 2026 20:37

fix(tool): support passing .go files to otelc go build

55cff43

improve test coverage

fb14fe3

address copilot feedback

4494a2d

fix module resolution for file based builds

6fae23c

minor cleanup

70e3eaf

address review comments

e406a18

amazingakai force-pushed the support-go-files branch from a6ce8f6 to e406a18 Compare May 19, 2026 15:12

fix test

88fe92e

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amazingakai commented May 10, 2026

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amazingakai commented May 15, 2026

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amazingakai commented May 19, 2026

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