FIX BOFT setting env vars breaks C++ compilation (#1739)

Resolves #1738

src/peft/tuners/boft/layer.py

@@ -20,6 +20,7 @@
 import math
 import os
 import warnings
+from contextlib import contextmanager
 from typing import Any, Optional, Union
 
 import torch
@@ -31,13 +32,46 @@
 from peft.tuners.tuners_utils import BaseTunerLayer, check_adapters_to_merge
 
 
-os.environ["CC"] = "gcc"
-os.environ["CXX"] = "gcc"
-curr_dir = os.path.dirname(__file__)
-
 _FBD_CUDA = None
 
 
+# this function is a 1:1 copy from accelerate
+@contextmanager
+def patch_environment(**kwargs):
+    """
+    A context manager that will add each keyword argument passed to `os.environ` and remove them when exiting.
+
+    Will convert the values in `kwargs` to strings and upper-case all the keys.
+
+    Example:
+
+    ```python
+    >>> import os
+    >>> from accelerate.utils import patch_environment
+
+    >>> with patch_environment(FOO="bar"):
+    ...     print(os.environ["FOO"])  # prints "bar"
+    >>> print(os.environ["FOO"])  # raises KeyError
+    ```
+    """
+    existing_vars = {}
+    for key, value in kwargs.items():
+        key = key.upper()
+        if key in os.environ:
+            existing_vars[key] = os.environ[key]
+        os.environ[key] = str(value)
+
+    yield
+
+    for key in kwargs:
+        key = key.upper()
+        if key in existing_vars:
+            # restore previous value
+            os.environ[key] = existing_vars[key]
+        else:
+            os.environ.pop(key, None)
+
+
 def get_fbd_cuda():
     global _FBD_CUDA
 
@@ -47,14 +81,15 @@ def get_fbd_cuda():
     curr_dir = os.path.dirname(__file__)
     # need ninja to build the extension
     try:
-        fbd_cuda = load(
-            name="fbd_cuda",
-            sources=[f"{curr_dir}/fbd/fbd_cuda.cpp", f"{curr_dir}/fbd/fbd_cuda_kernel.cu"],
-            verbose=True,
-            # build_directory='/tmp/'  # for debugging
-        )
-        # extra_cuda_cflags = ['-std=c++14', '-ccbin=$$(which gcc-7)']) # cuda10.2 is not compatible with gcc9. Specify gcc 7
-        import fbd_cuda
+        with patch_environment(CC="gcc", CXX="gcc"):
+            fbd_cuda = load(
+                name="fbd_cuda",
+                sources=[f"{curr_dir}/fbd/fbd_cuda.cpp", f"{curr_dir}/fbd/fbd_cuda_kernel.cu"],
+                verbose=True,
+                # build_directory='/tmp/'  # for debugging
+            )
+            # extra_cuda_cflags = ['-std=c++14', '-ccbin=$$(which gcc-7)']) # cuda10.2 is not compatible with gcc9. Specify gcc 7
+            import fbd_cuda
     except Exception as e:
         warnings.warn(f"Failed to load the CUDA extension: {e}, check if ninja is available.")
         warnings.warn("Setting boft_n_butterfly_factor to 1 to speed up the finetuning process.")