ignore files marked with go:build tools

cmd/paramgen/internal/paramgen.go

@@ -123,6 +123,18 @@ func parsePackage(path string) (*ast.Package, error) {
 	if len(pkgs) == 0 {
 		return nil, fmt.Errorf("no source-code package in directory %s", path)
 	}
+	// Ignore files with go:build constraint set to "tools" (common pattern in
+	// Conduit connectors).
+	for pkgName, pkg := range pkgs {
+		for fileName, f := range pkg.Files {
+			if hasBuildConstraint(f, "tools") {
+				delete(pkg.Files, fileName)
+			}
+		}
+		if len(pkg.Files) == 0 {
+			delete(pkgs, pkgName)
+		}
+	}
 	if len(pkgs) > 1 {
 		return nil, fmt.Errorf("multiple packages %v in directory %s", maps.Keys(pkgs), path)
 	}
@@ -132,6 +144,20 @@ func parsePackage(path string) (*ast.Package, error) {
 	panic("unreachable")
 }
 
+// hasBuildConstraint is a very naive way to check if a file has a build
+// constraint. It is sufficient for our use case.
+func hasBuildConstraint(f *ast.File, constraint string) bool {
+	text := fmt.Sprintf("//go:build %s", constraint)
+	for _, cg := range f.Comments {
+		for _, c := range cg.List {
+			if c.Text == text {
+				return true
+			}
+		}
+	}
+	return false
+}
+
 func findStruct(pkg *ast.Package, name string) (*ast.StructType, *ast.File, error) {
 	var structType *ast.StructType
 	var file *ast.File

cmd/paramgen/internal/testdata/complex/tools.go

@@ -0,0 +1,19 @@
+// Copyright © 2024 Meroxa, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build tools
+
+// This file should be ignored because of the build tag.
+
+package main