further tweaks to reporting

bitsandbytes/cextension.py

@@ -3,6 +3,7 @@ import logging
 import os
 from pathlib import Path
 import re
+from typing import Optional
 
 import torch
 
@@ -75,6 +76,91 @@ def get_available_cuda_binaries() -> list[str]:
     return sorted(versions)
 
 
+def parse_cuda_version(version_str: str) -> str:
+    """Convert raw version string (e.g. '118' from env var) to formatted version (e.g. '11.8')"""
+    if version_str.isdigit() and len(version_str) == 3:
+        return f"{version_str[:2]}.{version_str[2]}"
+    return version_str  # fallback as safety net
+
+
+def _format_cuda_error_message(
+    available_versions: list[str],
+    user_cuda_version: str,
+    override_info: str,
+    original_error: str = "",
+    include_diagnostics: bool = False,
+    include_override_notes: bool = False,
+    required_version: Optional[str] = None,
+    version_missing: bool = False,
+) -> str:
+    version_list = ", ".join(available_versions) if available_versions else "none"
+    base_msg = "Attempted to use bitsandbytes native library functionality but it's not available.\n\n"
+
+    # Explicit version availability check
+    version_alert = ""
+    if version_missing and required_version:
+        version_list_str = "\n- " + "\n- ".join(available_versions) if available_versions else "NONE"
+        version_alert = (
+            f"🚨 CUDA VERSION MISMATCH 🚨\n"
+            f"Requested CUDA version:  {required_version}\n"
+            f"Available pre-compiled versions: {version_list_str}\n\n"
+            "This means:\n"
+            "1. The version you're trying to use is NOT distributed with this package\n"
+            "2. You MUST compile from source for this specific CUDA version\n"
+            "3. The installation will NOT work until you compile or choose a CUDA supported version\n\n"
+        )
+
+    troubleshooting = (
+        "This typically happens when:\n"
+        "1. bitsandbytes doesn't ship with a pre-compiled binary for your CUDA version\n"
+        "2. The library wasn't compiled properly during installation from source\n"
+        "3. Missing CUDA dependencies\n\n"
+    )
+
+    note = (
+        "To make bitsandbytes work, the compiled library version MUST exactly match the linked CUDA version.\n"
+        "If your CUDA version doesn't have a pre-compiled binary, you MUST compile from source.\n\n"
+    )
+
+    cuda_info = (
+        f"Detected PyTorch CUDA version: {user_cuda_version}\n"
+        f"Available pre-compiled bitsandbytes binaries for these CUDA versions: {version_list}\n"
+        f"{override_info}\n\n"
+    )
+
+    compile_instructions = (
+        (
+            "You have three options:\n"
+            "1. COMPILE FROM SOURCE (required if no binary exists):\n"
+            "   https://huggingface.co/docs/bitsandbytes/main/en/installation#cuda-compile\n"
+            "2. Use BNB_CUDA_VERSION to specify a DIFFERENT CUDA version from the detected one\n"
+            "3. Check LD_LIBRARY_PATH contains the correct CUDA libraries\n\n"
+        )
+        if include_override_notes
+        else ""
+    )
+
+    diagnostics = (
+        (
+            "🔍 Run this command for detailed diagnostics:\n"
+            "python -m bitsandbytes\n\n"
+            "If you've tried everything and still have issues:\n"
+            "1. Include ALL version info (operating system, bitsandbytes, pytorch, cuda, python)\n"
+            "2. Describe what you've tried in detail\n"
+            "3. Open an issue with this information:\n"
+            "   https://github.com/bitsandbytes-foundation/bitsandbytes/issues\n\n"
+        )
+        if include_diagnostics
+        else ""
+    )
+
+    return (
+        f"{version_alert}{base_msg}{troubleshooting}{cuda_info}"
+        f"{note}{compile_instructions}"
+        f"{original_error}\n{diagnostics}"
+    )
+
+
 class MockBNBNativeLibrary(BNBNativeLibrary):
     """
     Mock BNBNativeLibrary that raises an error when trying to use native library
@@ -89,43 +175,27 @@ class MockBNBNativeLibrary(BNBNativeLibrary):
 
     def __getattr__(self, name):
         available_versions = get_available_cuda_binaries()
-        version_list = ", ".join(available_versions) if available_versions else "none"
-
-        user_ver = "Not detected"
-        if self.user_cuda_version:
-            user_ver = f"{self.user_cuda_version[0]}.{self.user_cuda_version[1]}"
+        override_value = os.environ.get("BNB_CUDA_VERSION")
+        override_info = f"\nCUDA override: BNB_CUDA_VERSION={override_value}" if override_value else ""
 
-        override_value = os.environ.get("BNB_CUDA_VERSION", None)
-        override_info = (
-            f"\nCUDA version overridden with BNB_CUDA_VERSION={override_value} environment variable"
+        formatted_version = (
+            parse_cuda_version(override_value)
             if override_value
-            else ""
+            else f"{self.user_cuda_version[0]}.{self.user_cuda_version[1]}"
         )
-
-        note = "To make bitsandbytes work, the compiled version of the library must match the corresponding linked CUDA version. If you are using a CUDA version that doesn't come with a pre-compiled binary, the only solution is to compile the library from source."
-
-        cuda_info = (
-            f"Detected PyTorch CUDA version: {user_ver}\n"
-            f"Available pre-compiled bitsandbytes binaries for CUDA versions: {version_list}"
-            + override_info
-            + "\n\n"
-            + note
-            + "\n\n"
-        )
-
-        base_msg = "Attempted to use bitsandbytes native library functionality but it's not available.\n\n"
-        original_error = f"Original error: {self.error_msg}\n\n" if self.error_msg else ""
-        troubleshooting = (
-            "This typically happens when:\n"
-            "1. BNB doesn't ship with a pre-compiled binary for your CUDA version\n"
-            "2. The library wasn't compiled properly during installation from source\n"
-            "3. Missing CUDA dependencies\n\n"
+        required_version = formatted_version
+        version_missing = required_version not in available_versions
+
+        msg = _format_cuda_error_message(
+            available_versions=available_versions,
+            user_cuda_version=f"{self.user_cuda_version[0]}.{self.user_cuda_version[1]}",
+            override_info=override_info,
+            original_error=f"Original error: {self.error_msg}\n" if self.error_msg else "",
+            include_diagnostics=True,
+            required_version=formatted_version,
+            version_missing=version_missing,
         )
-        err_msg = (
-            base_msg + troubleshooting + cuda_info + original_error + ("Run 'python -m bitsandbytes' for diagnostics.")
-        )
-
-        raise RuntimeError(err_msg)
+        raise RuntimeError(msg)
 
     def __getitem__(self, name):
         return self.__getattr__(name)
@@ -142,7 +212,24 @@ def get_native_library() -> BNBNativeLibrary:
         if cuda_binary_path.exists():
             binary_path = cuda_binary_path
         else:
-            logger.warning("Could not find the bitsandbytes CUDA binary at %r", cuda_binary_path)
+            available_versions = get_available_cuda_binaries()
+            env_version = os.environ.get("BNB_CUDA_VERSION")
+            override_info = "\nCUDA override active" if env_version else ""
+
+            formatted_version = parse_cuda_version(env_version) if env_version else cuda_specs.cuda_version_string
+            required_version = formatted_version
+            version_missing = required_version not in available_versions
+
+            msg = _format_cuda_error_message(
+                available_versions=available_versions,
+                user_cuda_version=cuda_specs.cuda_version_string,
+                override_info=override_info,
+                include_override_notes=True,
+                required_version=formatted_version,
+                version_missing=version_missing,
+            )
+            logger.warning(msg)
+
     logger.debug(f"Loading bitsandbytes native library from: {binary_path}")
     dll = ct.cdll.LoadLibrary(str(binary_path))
 
@@ -165,7 +252,7 @@ except Exception as e:
     diagnostic_help = ""
     if torch.cuda.is_available():
         diagnostic_help = (
-            "CUDA Setup failed despite CUDA being available. "
+            "CUDA Setup failed despite CUDA being available.\n\n"
             "Please run the following command to get more information:\n\n"
             "python -m bitsandbytes\n\n"
             "Inspect the output of the command and see if you can locate CUDA libraries. "