Added more clear error messages when universal-ctags is disabled per issue #31

README.md

@@ -68,6 +68,8 @@ You can find more chat transcripts on the [examples page](https://aider.chat/exa
   * Or, by including `openai-api-key: sk-...` in an `.aider.config.yml` file
 
 3. Optionally, install [universal ctags](https://github.com/universal-ctags/ctags). This is helpful if you plan to use aider and GPT-4 with repositories that have more than a handful of files.  This allows aider to build a [map of your entire git repo](https://aider.chat/docs/ctags.html) and share it with GPT to help it better understand and modify large codebases.
+  * The `ctags` command needs to be on your shell path so that it will run by default when aider invokes `ctags ...`.
+  * You need a build which includes the json feature. You can check by running `ctags --version` and looking for `+json` in the `Optional compiled features` list.
 
 ## Usage
 

aider/coders/base_coder.py

@@ -178,7 +178,8 @@ class Coder:
                 self.io.tool_output(f"Repo-map: universal-ctags using {map_tokens} tokens")
             elif not self.repo_map.has_ctags and map_tokens > 0:
                 self.io.tool_output(
-                    f"Repo-map: basic using {map_tokens} tokens (universal-ctags not found)"
+                    f"Repo-map: basic using {map_tokens} tokens"
+                    f" ({self.repo_map.ctags_disabled_reason})"
                 )
             else:
                 self.io.tool_output("Repo-map: disabled because map_tokens == 0")

aider/repomap.py

@@ -65,6 +65,8 @@ class RepoMap:
     IDENT_CACHE_DIR = f".aider.ident.cache.v{CACHE_VERSION}"
     TAGS_CACHE_DIR = f".aider.tags.cache.v{CACHE_VERSION}"
 
+    ctags_disabled_reason = "ctags not initialized"
+
     def __init__(
         self,
         map_tokens=1024,
@@ -180,13 +182,32 @@ class RepoMap:
 
     def check_for_ctags(self):
         try:
+            executable = self.ctags_cmd[0]
+            cmd = [executable, "--version"]
+            output = subprocess.check_output(cmd, stderr=subprocess.PIPE).decode("utf-8")
+            output = output.lower()
+
+            cmd = " ".join(cmd)
+
+            if "universal ctags" not in output:
+                self.ctags_disabled_reason = f"{cmd} does not claim to be universal ctags"
+                return
+            if "+json" not in output:
+                self.ctags_disabled_reason = f"{cmd} does not list +json support"
+                return
+
             with tempfile.TemporaryDirectory() as tempdir:
                 hello_py = os.path.join(tempdir, "hello.py")
                 with open(hello_py, "w") as f:
                     f.write("def hello():\n    print('Hello, world!')\n")
                 self.run_ctags(hello_py)
-        except Exception:
-            return False
+        except FileNotFoundError:
+            self.ctags_disabled_reason = f"{executable} executable not found"
+            return
+        except Exception as err:
+            self.ctags_disabled_reason = f"error running universal-ctags: {err}"
+            return
+
         return True
 
     def load_tags_cache(self):