From c3245cd028977877aa9e485451b29c7736ebcae0 Mon Sep 17 00:00:00 2001
From: Fabian Meumertzheim <fabian@meumertzhe.im>
Date: Sun, 8 Jan 2023 20:40:42 -0800
Subject: [PATCH] Add `SpellChecker` suggestions for common Bzlmod errors

Closes #17121.

PiperOrigin-RevId: 500606458
Change-Id: I3a4c3650e8f89401669f1d5e941073ed603673db
---
 .../devtools/build/lib/bazel/bzlmod/BUILD     |  1 +
 .../bzlmod/SingleExtensionEvalFunction.java   | 19 +++++++++++++++----
 .../lib/bazel/bzlmod/TypeCheckedTag.java      |  6 ++++--
 3 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/src/main/java/com/google/devtools/build/lib/bazel/bzlmod/BUILD b/src/main/java/com/google/devtools/build/lib/bazel/bzlmod/BUILD
index 3c37edd9667c22..771b58e97ea21e 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/bzlmod/BUILD
+++ b/src/main/java/com/google/devtools/build/lib/bazel/bzlmod/BUILD
@@ -170,6 +170,7 @@ java_library(
         "//src/main/java/com/google/devtools/build/skyframe:skyframe-objects",
         "//src/main/java/net/starlark/java/annot",
         "//src/main/java/net/starlark/java/eval",
+        "//src/main/java/net/starlark/java/spelling",
         "//src/main/java/net/starlark/java/syntax",
         "//src/main/protobuf:failure_details_java_proto",
         "//third_party:auto_value",
diff --git a/src/main/java/com/google/devtools/build/lib/bazel/bzlmod/SingleExtensionEvalFunction.java b/src/main/java/com/google/devtools/build/lib/bazel/bzlmod/SingleExtensionEvalFunction.java
index 6eab1233834b9a..0418870181811b 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/bzlmod/SingleExtensionEvalFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/bzlmod/SingleExtensionEvalFunction.java
@@ -16,7 +16,9 @@
 package com.google.devtools.build.lib.bazel.bzlmod;
 
 import static com.google.common.collect.ImmutableBiMap.toImmutableBiMap;
+import static com.google.common.collect.ImmutableSet.toImmutableSet;
 
+import com.google.common.collect.ImmutableSet;
 import com.google.devtools.build.lib.analysis.BlazeDirectories;
 import com.google.devtools.build.lib.bazel.repository.downloader.DownloadManager;
 import com.google.devtools.build.lib.cmdline.BazelModuleContext;
@@ -51,6 +53,7 @@
 import net.starlark.java.eval.StarlarkList;
 import net.starlark.java.eval.StarlarkSemantics;
 import net.starlark.java.eval.StarlarkThread;
+import net.starlark.java.spelling.SpellChecker;
 import net.starlark.java.syntax.Location;
 
 /**
@@ -147,13 +150,19 @@ public SkyValue compute(SkyKey skyKey, Environment env)
     // Check that the .bzl file actually exports a module extension by our name.
     Object exported = bzlLoadValue.getModule().getGlobal(extensionId.getExtensionName());
     if (!(exported instanceof ModuleExtension.InStarlark)) {
+      ImmutableSet<String> exportedExtensions =
+          bzlLoadValue.getModule().getGlobals().entrySet().stream()
+              .filter(e -> e.getValue() instanceof ModuleExtension.InStarlark)
+              .map(Entry::getKey)
+              .collect(toImmutableSet());
       throw new SingleExtensionEvalFunctionException(
           ExternalDepsException.withMessage(
               Code.BAD_MODULE,
-              "%s does not export a module extension called %s, yet its use is requested at %s",
+              "%s does not export a module extension called %s, yet its use is requested at %s%s",
               extensionId.getBzlFileLabel(),
               extensionId.getExtensionName(),
-              sampleUsageLocation),
+              sampleUsageLocation,
+              SpellChecker.didYouMean(extensionId.getExtensionName(), exportedExtensions)),
           Transience.PERSISTENT);
     }
 
@@ -206,12 +215,14 @@ public SkyValue compute(SkyKey skyKey, Environment env)
               ExternalDepsException.withMessage(
                   Code.BAD_MODULE,
                   "module extension \"%s\" from \"%s\" does not generate repository \"%s\", yet it"
-                      + " is imported as \"%s\" in the usage at %s",
+                      + " is imported as \"%s\" in the usage at %s%s",
                   extensionId.getExtensionName(),
                   extensionId.getBzlFileLabel(),
                   repoImport.getValue(),
                   repoImport.getKey(),
-                  usage.getLocation()),
+                  usage.getLocation(),
+                  SpellChecker.didYouMean(
+                      repoImport.getValue(), threadContext.getGeneratedRepos().keySet())),
               Transience.PERSISTENT);
         }
       }
diff --git a/src/main/java/com/google/devtools/build/lib/bazel/bzlmod/TypeCheckedTag.java b/src/main/java/com/google/devtools/build/lib/bazel/bzlmod/TypeCheckedTag.java
index 855c8cb465a5b1..50c4b19e68525e 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/bzlmod/TypeCheckedTag.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/bzlmod/TypeCheckedTag.java
@@ -24,6 +24,7 @@
 import net.starlark.java.annot.StarlarkBuiltin;
 import net.starlark.java.eval.EvalException;
 import net.starlark.java.eval.Structure;
+import net.starlark.java.spelling.SpellChecker;
 
 /**
  * A {@link Tag} whose attribute values have been type-checked against the attribute schema define
@@ -48,9 +49,10 @@ public static TypeCheckedTag create(TagClass tagClass, Tag tag, LabelConverter l
       if (attrIndex == null) {
         throw ExternalDepsException.withMessage(
             Code.BAD_MODULE,
-            "in tag at %s, unknown attribute %s provided",
+            "in tag at %s, unknown attribute %s provided%s",
             tag.getLocation(),
-            attrValue.getKey());
+            attrValue.getKey(),
+            SpellChecker.didYouMean(attrValue.getKey(), tagClass.getAttributeIndices().keySet()));
       }
       Attribute attr = tagClass.getAttributes().get(attrIndex);
       Object nativeValue;