goImports: avoid collapsing new imports into pseudo import line

src/goImport.ts

@@ -83,6 +83,8 @@ export function getTextEditForAddImport(arg: string): vscode.TextEdit[] {
 	}
 
 	const multis = imports.filter((x) => x.kind === 'multi');
+	const minusCgo = imports.filter((x) => x.kind !== 'pseudo');
+
 	if (multis.length > 0) {
 		// There is a multiple import declaration, add to the last one
 		const lastImportSection = multis[multis.length - 1];
@@ -92,12 +94,12 @@ export function getTextEditForAddImport(arg: string): vscode.TextEdit[] {
 		}
 		// Add import at the start of the block so that goimports/goreturns can order them correctly
 		return [vscode.TextEdit.insert(new vscode.Position(lastImportSection.start + 1, 0), '\t"' + arg + '"\n')];
-	} else if (imports.length > 0) {
+	} else if (minusCgo.length > 0) {
 		// There are some number of single line imports, which can just be collapsed into a block import.
 		const edits = [];
 
-		edits.push(vscode.TextEdit.insert(new vscode.Position(imports[0].start, 0), 'import (\n\t"' + arg + '"\n'));
-		imports.forEach((element) => {
+		edits.push(vscode.TextEdit.insert(new vscode.Position(minusCgo[0].start, 0), 'import (\n\t"' + arg + '"\n'));
+		minusCgo.forEach((element) => {
 			const currentLine = vscode.window.activeTextEditor.document.lineAt(element.start).text;
 			const updatedLine = currentLine.replace(/^\s*import\s*/, '\t');
 			edits.push(
@@ -107,7 +109,7 @@ export function getTextEditForAddImport(arg: string): vscode.TextEdit[] {
 				)
 			);
 		});
-		edits.push(vscode.TextEdit.insert(new vscode.Position(imports[imports.length - 1].end + 1, 0), ')\n'));
+		edits.push(vscode.TextEdit.insert(new vscode.Position(minusCgo[minusCgo.length - 1].end + 1, 0), ')\n'));
 
 		return edits;
 	} else if (pkg && pkg.start >= 0) {

src/util.ts

@@ -156,11 +156,12 @@ export function parseFilePrelude(text: string): Prelude {
 		}
 		if (line.match(/^(\s)*import(\s)+\(/)) {
 			ret.imports.push({ kind: 'multi', start: i, end: -1, pkgs: [] });
-		}
-		if (line.match(/^(\s)*import(\s)+[^\(]/)) {
+		} else if (line.match(/^\s*import\s+"C"/)) {
+			ret.imports.push({ kind: 'pseudo', start: i, end: i, pkgs: [] });
+		} else if (line.match(/^(\s)*import(\s)+[^\(]/)) {
 			ret.imports.push({ kind: 'single', start: i, end: i, pkgs: [] });
 		}
-		if (line.match(/^(\s)*(\/\*.*\*\/)*\s*\)/)) {
+		if (line.match(/^(\s)*(\/\*.*\*\/)*\s*\)/)) {  // /* comments */
 			if (ret.imports[ret.imports.length - 1].end === -1) {
 				ret.imports[ret.imports.length - 1].end = i;
 			}

test/fixtures/importTest/cgoImports.go

@@ -0,0 +1,10 @@
+package main
+
+//#include <stdlib.h>
+import "C"
+
+import "math"
+
+func main() {
+	_ = math.Max(1, 2)
+}

test/integration/extension.test.ts

@@ -162,6 +162,10 @@ suite('Go Extension Tests', function () {
 			path.join(fixtureSourcePath, 'importTest', 'singleImports.go'),
 			path.join(fixturePath, 'importTest', 'singleImports.go')
 		);
+		fs.copySync(
+			path.join(fixtureSourcePath, 'importTest', 'cgoImports.go'),
+			path.join(fixturePath, 'importTest', 'cgoImports.go')
+		);
 		fs.copySync(
 			path.join(fixtureSourcePath, 'fillStruct', 'input_1.go'),
 			path.join(fixturePath, 'fillStruct', 'input_1.go')
@@ -1590,6 +1594,24 @@ encountered.
 		assert.equal(vscode.window.activeTextEditor && vscode.window.activeTextEditor.document.getText(), expectedText);
 	});
 
+	test('Add imports and avoid pseudo package imports for cgo', async () => {
+		const uri = vscode.Uri.file(path.join(fixturePath, 'importTest', 'cgoImports.go'));
+		const document = await vscode.workspace.openTextDocument(uri);
+		await vscode.window.showTextDocument(document);
+
+		const expectedText = document
+			.getText()
+			.replace(
+				'import "math"',
+				'import (\n\t"bytes"\n\t"math"\n)'
+			);
+		const edits = getTextEditForAddImport('bytes');
+		const edit = new vscode.WorkspaceEdit();
+		edit.set(document.uri, edits);
+		await vscode.workspace.applyEdit(edit);
+		assert.equal(vscode.window.activeTextEditor && vscode.window.activeTextEditor.document.getText(), expectedText);
+	});
+
 	test('Fill struct', async () => {
 		const uri = vscode.Uri.file(path.join(fixturePath, 'fillStruct', 'input_1.go'));
 		const golden = fs.readFileSync(path.join(fixturePath, 'fillStruct', 'golden_1.go'), 'utf-8');