From 68a8d1ffb12664af67cb856e59715d0e9958480c Mon Sep 17 00:00:00 2001
From: Ramya Achutha Rao <ramyar@microsoft.com>
Date: Tue, 14 Nov 2017 18:57:37 -0800
Subject: [PATCH] Show error in references codelens instead of 0 Fixes #1336

---
 src/goReferences.ts         | 19 +++++++++++--------
 src/goReferencesCodelens.ts | 28 ++++++++++++++--------------
 2 files changed, 25 insertions(+), 22 deletions(-)

diff --git a/src/goReferences.ts b/src/goReferences.ts
index 221180bf1..a9c7d6658 100644
--- a/src/goReferences.ts
+++ b/src/goReferences.ts
@@ -19,30 +19,33 @@ export class GoReferenceProvider implements vscode.ReferenceProvider {
 
 	private doFindReferences(document: vscode.TextDocument, position: vscode.Position, options: { includeDeclaration: boolean }, token: vscode.CancellationToken): Thenable<vscode.Location[]> {
 		return new Promise<vscode.Location[]>((resolve, reject) => {
-			let filename = canonicalizeGOPATHPrefix(document.fileName);
-			let cwd = path.dirname(filename);
-
 			// get current word
 			let wordRange = document.getWordRangeAtPosition(position);
 			if (!wordRange) {
 				return resolve([]);
 			}
 
+			let goGuru = getBinPath('guru');
+			if (!path.isAbsolute(goGuru)) {
+				promptForMissingTool('guru');
+				return reject('Cannot find tool "guru" to find references.');
+			}
+
+			let filename = canonicalizeGOPATHPrefix(document.fileName);
+			let cwd = path.dirname(filename);
 			let offset = byteOffsetAt(document, position);
 			let env = getToolsEnvVars();
-			let goGuru = getBinPath('guru');
 			let buildTags = '"' + vscode.workspace.getConfiguration('go', document.uri)['buildTags'] + '"';
 
-			let process = cp.execFile(goGuru, ['-modified', '-tags', buildTags, 'referrers', `${filename}:#${offset.toString()}`], {env}, (err, stdout, stderr) => {
+			let process = cp.execFile(goGuru, ['-modified', '-tags', buildTags, 'referrers', `${filename}:#${offset.toString()}`], { env }, (err, stdout, stderr) => {
 				try {
 					if (err && (<any>err).code === 'ENOENT') {
 						promptForMissingTool('guru');
-						return resolve([]);
+						return reject('Cannot find tool "guru" to find references.')
 					}
 
 					if (err && (<any>err).killed !== true) {
-						console.log(err);
-						return resolve([]);
+						return reject(`Error running guru: ${err.message || stderr}`);
 					}
 
 					let lines = stdout.toString().split('\n');
diff --git a/src/goReferencesCodelens.ts b/src/goReferencesCodelens.ts
index b0a44b354..d600281c7 100644
--- a/src/goReferencesCodelens.ts
+++ b/src/goReferencesCodelens.ts
@@ -56,20 +56,20 @@ export class GoReferencesCodeLensProvider extends GoBaseCodeLensProvider {
 		};
 		let referenceProvider = new GoReferenceProvider();
 		return referenceProvider.provideReferences(codeLens.document, codeLens.range.start, options, token).then(references => {
-			if (references) {
-				codeLens.command = {
-					title: references.length === 1
-						? '1 reference'
-						: references.length + ' references',
-					command: 'editor.action.showReferences',
-					arguments: [codeLens.document.uri, codeLens.range.start, references]
-				};
-			} else {
-				codeLens.command = {
-					title: 'No references found',
-					command: ''
-				};
-			}
+			codeLens.command = {
+				title: references.length === 1
+					? '1 reference'
+					: references.length + ' references',
+				command: 'editor.action.showReferences',
+				arguments: [codeLens.document.uri, codeLens.range.start, references]
+			};
+			return codeLens;
+		}, err => {
+			console.log(err);
+			codeLens.command = {
+				title: 'Error finding references',
+				command: ''
+			};
 			return codeLens;
 		});
 	}