We are currently solving the following issue within our repository. Here is the issue text:
--- BEGIN ISSUE ---
Installation issue: tcl with <= gcc@11
### Steps to reproduce

I started the most up to date version of spack, 05-12-2023, and had a glitch when trying to compile `tcl`:

    spack install -v tcl@8.6.11
    
it appears to be as a result of the addition of this edit [40946](https://github.com/spack/spack/pull/40946)

    filter_compiler_wrappers("tclConfig.sh", relative_root="lib")
    
I think the error is related to the `filter_compile_wrappers function` trying to replace a line containing `gcc` and `g++`, however the file in question, `tclConfig.sh` only has one line containing `gcc`, no `g++`:

    # C compiler to use for compilation.
    TCL_CC='/mnt/sda/cadtools/spack_git/lib/spack/env/gcc/gcc'


My base system, ubuntu22.04, has `gcc@11.4.0` as its default. I have stripped this back to a clean checkout of spack and go straight into a compile of `tcl`.

If I compile and instead use `gcc@12.3.` it do not get the error, the installation is successful. Also if I comment out that one line from the `tcl/package.py` file, the installation is successful using `gcc@11.4.0`.

### Error message

```
==> [2023-12-05-10:43:44.657378] Find complete: /mnt/sda/cadtools/spack_install/opt/linux-ubuntu22.04-skylake/gcc-11.4.0/tcl/8.6.11-yvwju3kstvxvughqov6ommkuxr7mzrpm/lib ('tclConfig.sh',)
==> [2023-12-05-10:43:44.658905] FILTER FILE: /mnt/sda/cadtools/spack_install/opt/linux-ubuntu22.04-skylake/gcc-11.4.0/tcl/8.6.11-yvwju3kstvxvughqov6ommkuxr7mzrpm/lib/tclConfig.sh [replacing "/mnt/sda/cadtools/spack_git/lib/spack/env/gcc/gcc"]
==> [2023-12-05-10:43:44.659794] FILTER FILE: /mnt/sda/cadtools/spack_install/opt/linux-ubuntu22.04-skylake/gcc-11.4.0/tcl/8.6.11-yvwju3kstvxvughqov6ommkuxr7mzrpm/lib/tclConfig.sh [replacing "/mnt/sda/cadtools/spack_git/lib/spack/env/gcc/g\+\+"]
==> Error: AttributeError: 'NoneType' object has no attribute 'replace'
```

### Information on your system

* **Spack:** 0.22.0.dev0 (798770f9e54bfd3cb1a52af4a9bd2937f826018e)
* **Python:** 3.11.6
* **Platform:** linux-ubuntu22.04-skylake
* **Concretizer:** clingo


### General information

- [X] I have run `spack debug report` and reported the version of Spack/Python/Platform
- [X] I have searched the issues of this repo and believe this is not a duplicate
- [X] I have run the failing commands in debug mode and reported the output

--- END ISSUE ---

Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
--- BEGIN FILES ---
Path: `lib/spack/spack/mixins.py`
Content:
```
1 # Copyright 2013-2023 Lawrence Livermore National Security, LLC and other
2 # Spack Project Developers. See the top-level COPYRIGHT file for details.
3 #
4 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
5 
6 """This module contains additional behavior that can be attached to any given
7 package.
8 """
9 import os
10 
11 import llnl.util.filesystem
12 
13 import spack.builder
14 
15 
16 def filter_compiler_wrappers(*files, **kwargs):
17     """Substitutes any path referring to a Spack compiler wrapper with the
18     path of the underlying compiler that has been used.
19 
20     If this isn't done, the files will have CC, CXX, F77, and FC set to
21     Spack's generic cc, c++, f77, and f90. We want them to be bound to
22     whatever compiler they were built with.
23 
24     Args:
25         *files: files to be filtered relative to the search root (which is,
26             by default, the installation prefix)
27 
28         **kwargs: allowed keyword arguments
29 
30             after
31                 specifies after which phase the files should be
32                 filtered (defaults to 'install')
33 
34             relative_root
35                 path relative to prefix where to start searching for
36                 the files to be filtered. If not set the install prefix
37                 wil be used as the search root. **It is highly recommended
38                 to set this, as searching from the installation prefix may
39                 affect performance severely in some cases**.
40 
41             ignore_absent, backup
42                 these two keyword arguments, if present, will be forwarded
43                 to ``filter_file`` (see its documentation for more information
44                 on their behavior)
45 
46             recursive
47                 this keyword argument, if present, will be forwarded to
48                 ``find`` (see its documentation for more information on the
49                 behavior)
50     """
51     after = kwargs.get("after", "install")
52     relative_root = kwargs.get("relative_root", None)
53 
54     filter_kwargs = {
55         "ignore_absent": kwargs.get("ignore_absent", True),
56         "backup": kwargs.get("backup", False),
57         "string": True,
58     }
59 
60     find_kwargs = {"recursive": kwargs.get("recursive", False)}
61 
62     def _filter_compiler_wrappers_impl(pkg_or_builder):
63         pkg = getattr(pkg_or_builder, "pkg", pkg_or_builder)
64         # Compute the absolute path of the search root
65         root = os.path.join(pkg.prefix, relative_root) if relative_root else pkg.prefix
66 
67         # Compute the absolute path of the files to be filtered and
68         # remove links from the list.
69         abs_files = llnl.util.filesystem.find(root, files, **find_kwargs)
70         abs_files = [x for x in abs_files if not os.path.islink(x)]
71 
72         x = llnl.util.filesystem.FileFilter(*abs_files)
73 
74         compiler_vars = [
75             ("CC", pkg.compiler.cc),
76             ("CXX", pkg.compiler.cxx),
77             ("F77", pkg.compiler.f77),
78             ("FC", pkg.compiler.fc),
79         ]
80 
81         # Some paths to the compiler wrappers might be substrings of the others.
82         # For example:
83         #   CC=/path/to/spack/lib/spack/env/cc (realpath to the wrapper)
84         #   FC=/path/to/spack/lib/spack/env/cce/ftn
85         # Therefore, we perform the filtering in the reversed sorted order of
86         # the substituted strings. If, however, the strings are identical (e.g.
87         # both CC and FC are set using realpath), the filtering is done
88         # according to the order in compiler_vars. To achieve that, we populate
89         # the following array with tuples of three elements: path to the
90         # wrapper, negated index of the variable in compiler_vars, path to the
91         # real compiler. This way, the reversed sorted order of the resulting
92         # array is the order of replacements that we need.
93         replacements = []
94 
95         for idx, (env_var, compiler_path) in enumerate(compiler_vars):
96             if env_var in os.environ:
97                 # filter spack wrapper and links to spack wrapper in case
98                 # build system runs realpath
99                 wrapper = os.environ[env_var]
100                 for wrapper_path in (wrapper, os.path.realpath(wrapper)):
101                     replacements.append((wrapper_path, -idx, compiler_path))
102 
103         for wrapper_path, _, compiler_path in sorted(replacements, reverse=True):
104             x.filter(wrapper_path, compiler_path, **filter_kwargs)
105 
106         # Remove this linking flag if present (it turns RPATH into RUNPATH)
107         x.filter("{0}--enable-new-dtags".format(pkg.compiler.linker_arg), "", **filter_kwargs)
108 
109         # NAG compiler is usually mixed with GCC, which has a different
110         # prefix for linker arguments.
111         if pkg.compiler.name == "nag":
112             x.filter("-Wl,--enable-new-dtags", "", **filter_kwargs)
113 
114     spack.builder.run_after(after)(_filter_compiler_wrappers_impl)
115
```
--- END FILES ---

Please first localize the bug based on the issue statement, and then generate a patch according to the `git diff` format fenced by three backticks.

Here is an example:

```diff
diff --git a/examples/server_async.py b/examples/server_async.py
--- a/examples/server_async.py
+++ b/examples/server_async.py
@@ -313,4 +313,4 @@
 
 
 if __name__ == "__main__":
-    asyncio.run(run_async_server("."), debug=True)
+    asyncio.run(run_async_server(), debug=True)
diff --git a/examples/server_sync.py b/examples/server_sync.py
--- a/examples/server_sync.py
+++ b/examples/server_sync.py
@@ -313,5 +313,5 @@
 
 
 if __name__ == "__main__":
-    server = run_sync_server(".")
+    server = run_sync_server()
     server.shutdown()

```

diff --git a/lib/spack/spack/mixins.py b/lib/spack/spack/mixins.py
--- a/lib/spack/spack/mixins.py
+++ b/lib/spack/spack/mixins.py
@@ -93,7 +93,7 @@
         replacements = []
 
         for idx, (env_var, compiler_path) in enumerate(compiler_vars):
-            if env_var in os.environ:
+            if env_var in os.environ and compiler_path is not None:
                 # filter spack wrapper and links to spack wrapper in case
                 # build system runs realpath
                 wrapper = os.environ[env_var]

{"golden_diff": "diff --git a/lib/spack/spack/mixins.py b/lib/spack/spack/mixins.py\n--- a/lib/spack/spack/mixins.py\n+++ b/lib/spack/spack/mixins.py\n@@ -93,7 +93,7 @@\n         replacements = []\n \n         for idx, (env_var, compiler_path) in enumerate(compiler_vars):\n-            if env_var in os.environ:\n+            if env_var in os.environ and compiler_path is not None:\n                 # filter spack wrapper and links to spack wrapper in case\n                 # build system runs realpath\n                 wrapper = os.environ[env_var]\n", "issue": "Installation issue: tcl with <= gcc@11\n### Steps to reproduce\r\n\r\nI started the most up to date version of spack, 05-12-2023, and had a glitch when trying to compile `tcl`:\r\n\r\n    spack install -v tcl@8.6.11\r\n    \r\nit appears to be as a result of the addition of this edit [40946](https://github.com/spack/spack/pull/40946)\r\n\r\n    filter_compiler_wrappers(\"tclConfig.sh\", relative_root=\"lib\")\r\n    \r\nI think the error is related to the `filter_compile_wrappers function` trying to replace a line containing `gcc` and `g++`, however the file in question, `tclConfig.sh` only has one line containing `gcc`, no `g++`:\r\n\r\n    # C compiler to use for compilation.\r\n    TCL_CC='/mnt/sda/cadtools/spack_git/lib/spack/env/gcc/gcc'\r\n\r\n\r\nMy base system, ubuntu22.04, has `gcc@11.4.0` as its default. I have stripped this back to a clean checkout of spack and go straight into a compile of `tcl`.\r\n\r\nIf I compile and instead use `gcc@12.3.` it do not get the error, the installation is successful. Also if I comment out that one line from the `tcl/package.py` file, the installation is successful using `gcc@11.4.0`.\r\n\r\n### Error message\r\n\r\n```\r\n==> [2023-12-05-10:43:44.657378] Find complete: /mnt/sda/cadtools/spack_install/opt/linux-ubuntu22.04-skylake/gcc-11.4.0/tcl/8.6.11-yvwju3kstvxvughqov6ommkuxr7mzrpm/lib ('tclConfig.sh',)\r\n==> [2023-12-05-10:43:44.658905] FILTER FILE: /mnt/sda/cadtools/spack_install/opt/linux-ubuntu22.04-skylake/gcc-11.4.0/tcl/8.6.11-yvwju3kstvxvughqov6ommkuxr7mzrpm/lib/tclConfig.sh [replacing \"/mnt/sda/cadtools/spack_git/lib/spack/env/gcc/gcc\"]\r\n==> [2023-12-05-10:43:44.659794] FILTER FILE: /mnt/sda/cadtools/spack_install/opt/linux-ubuntu22.04-skylake/gcc-11.4.0/tcl/8.6.11-yvwju3kstvxvughqov6ommkuxr7mzrpm/lib/tclConfig.sh [replacing \"/mnt/sda/cadtools/spack_git/lib/spack/env/gcc/g\\+\\+\"]\r\n==> Error: AttributeError: 'NoneType' object has no attribute 'replace'\r\n```\r\n\r\n### Information on your system\r\n\r\n* **Spack:** 0.22.0.dev0 (798770f9e54bfd3cb1a52af4a9bd2937f826018e)\r\n* **Python:** 3.11.6\r\n* **Platform:** linux-ubuntu22.04-skylake\r\n* **Concretizer:** clingo\r\n\r\n\r\n### General information\r\n\r\n- [X] I have run `spack debug report` and reported the version of Spack/Python/Platform\r\n- [X] I have searched the issues of this repo and believe this is not a duplicate\r\n- [X] I have run the failing commands in debug mode and reported the output\n", "before_files": [{"content": "# Copyright 2013-2023 Lawrence Livermore National Security, LLC and other\n# Spack Project Developers. See the top-level COPYRIGHT file for details.\n#\n# SPDX-License-Identifier: (Apache-2.0 OR MIT)\n\n\"\"\"This module contains additional behavior that can be attached to any given\npackage.\n\"\"\"\nimport os\n\nimport llnl.util.filesystem\n\nimport spack.builder\n\n\ndef filter_compiler_wrappers(*files, **kwargs):\n    \"\"\"Substitutes any path referring to a Spack compiler wrapper with the\n    path of the underlying compiler that has been used.\n\n    If this isn't done, the files will have CC, CXX, F77, and FC set to\n    Spack's generic cc, c++, f77, and f90. We want them to be bound to\n    whatever compiler they were built with.\n\n    Args:\n        *files: files to be filtered relative to the search root (which is,\n            by default, the installation prefix)\n\n        **kwargs: allowed keyword arguments\n\n            after\n                specifies after which phase the files should be\n                filtered (defaults to 'install')\n\n            relative_root\n                path relative to prefix where to start searching for\n                the files to be filtered. If not set the install prefix\n                wil be used as the search root. **It is highly recommended\n                to set this, as searching from the installation prefix may\n                affect performance severely in some cases**.\n\n            ignore_absent, backup\n                these two keyword arguments, if present, will be forwarded\n                to ``filter_file`` (see its documentation for more information\n                on their behavior)\n\n            recursive\n                this keyword argument, if present, will be forwarded to\n                ``find`` (see its documentation for more information on the\n                behavior)\n    \"\"\"\n    after = kwargs.get(\"after\", \"install\")\n    relative_root = kwargs.get(\"relative_root\", None)\n\n    filter_kwargs = {\n        \"ignore_absent\": kwargs.get(\"ignore_absent\", True),\n        \"backup\": kwargs.get(\"backup\", False),\n        \"string\": True,\n    }\n\n    find_kwargs = {\"recursive\": kwargs.get(\"recursive\", False)}\n\n    def _filter_compiler_wrappers_impl(pkg_or_builder):\n        pkg = getattr(pkg_or_builder, \"pkg\", pkg_or_builder)\n        # Compute the absolute path of the search root\n        root = os.path.join(pkg.prefix, relative_root) if relative_root else pkg.prefix\n\n        # Compute the absolute path of the files to be filtered and\n        # remove links from the list.\n        abs_files = llnl.util.filesystem.find(root, files, **find_kwargs)\n        abs_files = [x for x in abs_files if not os.path.islink(x)]\n\n        x = llnl.util.filesystem.FileFilter(*abs_files)\n\n        compiler_vars = [\n            (\"CC\", pkg.compiler.cc),\n            (\"CXX\", pkg.compiler.cxx),\n            (\"F77\", pkg.compiler.f77),\n            (\"FC\", pkg.compiler.fc),\n        ]\n\n        # Some paths to the compiler wrappers might be substrings of the others.\n        # For example:\n        #   CC=/path/to/spack/lib/spack/env/cc (realpath to the wrapper)\n        #   FC=/path/to/spack/lib/spack/env/cce/ftn\n        # Therefore, we perform the filtering in the reversed sorted order of\n        # the substituted strings. If, however, the strings are identical (e.g.\n        # both CC and FC are set using realpath), the filtering is done\n        # according to the order in compiler_vars. To achieve that, we populate\n        # the following array with tuples of three elements: path to the\n        # wrapper, negated index of the variable in compiler_vars, path to the\n        # real compiler. This way, the reversed sorted order of the resulting\n        # array is the order of replacements that we need.\n        replacements = []\n\n        for idx, (env_var, compiler_path) in enumerate(compiler_vars):\n            if env_var in os.environ:\n                # filter spack wrapper and links to spack wrapper in case\n                # build system runs realpath\n                wrapper = os.environ[env_var]\n                for wrapper_path in (wrapper, os.path.realpath(wrapper)):\n                    replacements.append((wrapper_path, -idx, compiler_path))\n\n        for wrapper_path, _, compiler_path in sorted(replacements, reverse=True):\n            x.filter(wrapper_path, compiler_path, **filter_kwargs)\n\n        # Remove this linking flag if present (it turns RPATH into RUNPATH)\n        x.filter(\"{0}--enable-new-dtags\".format(pkg.compiler.linker_arg), \"\", **filter_kwargs)\n\n        # NAG compiler is usually mixed with GCC, which has a different\n        # prefix for linker arguments.\n        if pkg.compiler.name == \"nag\":\n            x.filter(\"-Wl,--enable-new-dtags\", \"\", **filter_kwargs)\n\n    spack.builder.run_after(after)(_filter_compiler_wrappers_impl)\n", "path": "lib/spack/spack/mixins.py"}], "after_files": [{"content": "# Copyright 2013-2023 Lawrence Livermore National Security, LLC and other\n# Spack Project Developers. See the top-level COPYRIGHT file for details.\n#\n# SPDX-License-Identifier: (Apache-2.0 OR MIT)\n\n\"\"\"This module contains additional behavior that can be attached to any given\npackage.\n\"\"\"\nimport os\n\nimport llnl.util.filesystem\n\nimport spack.builder\n\n\ndef filter_compiler_wrappers(*files, **kwargs):\n    \"\"\"Substitutes any path referring to a Spack compiler wrapper with the\n    path of the underlying compiler that has been used.\n\n    If this isn't done, the files will have CC, CXX, F77, and FC set to\n    Spack's generic cc, c++, f77, and f90. We want them to be bound to\n    whatever compiler they were built with.\n\n    Args:\n        *files: files to be filtered relative to the search root (which is,\n            by default, the installation prefix)\n\n        **kwargs: allowed keyword arguments\n\n            after\n                specifies after which phase the files should be\n                filtered (defaults to 'install')\n\n            relative_root\n                path relative to prefix where to start searching for\n                the files to be filtered. If not set the install prefix\n                wil be used as the search root. **It is highly recommended\n                to set this, as searching from the installation prefix may\n                affect performance severely in some cases**.\n\n            ignore_absent, backup\n                these two keyword arguments, if present, will be forwarded\n                to ``filter_file`` (see its documentation for more information\n                on their behavior)\n\n            recursive\n                this keyword argument, if present, will be forwarded to\n                ``find`` (see its documentation for more information on the\n                behavior)\n    \"\"\"\n    after = kwargs.get(\"after\", \"install\")\n    relative_root = kwargs.get(\"relative_root\", None)\n\n    filter_kwargs = {\n        \"ignore_absent\": kwargs.get(\"ignore_absent\", True),\n        \"backup\": kwargs.get(\"backup\", False),\n        \"string\": True,\n    }\n\n    find_kwargs = {\"recursive\": kwargs.get(\"recursive\", False)}\n\n    def _filter_compiler_wrappers_impl(pkg_or_builder):\n        pkg = getattr(pkg_or_builder, \"pkg\", pkg_or_builder)\n        # Compute the absolute path of the search root\n        root = os.path.join(pkg.prefix, relative_root) if relative_root else pkg.prefix\n\n        # Compute the absolute path of the files to be filtered and\n        # remove links from the list.\n        abs_files = llnl.util.filesystem.find(root, files, **find_kwargs)\n        abs_files = [x for x in abs_files if not os.path.islink(x)]\n\n        x = llnl.util.filesystem.FileFilter(*abs_files)\n\n        compiler_vars = [\n            (\"CC\", pkg.compiler.cc),\n            (\"CXX\", pkg.compiler.cxx),\n            (\"F77\", pkg.compiler.f77),\n            (\"FC\", pkg.compiler.fc),\n        ]\n\n        # Some paths to the compiler wrappers might be substrings of the others.\n        # For example:\n        #   CC=/path/to/spack/lib/spack/env/cc (realpath to the wrapper)\n        #   FC=/path/to/spack/lib/spack/env/cce/ftn\n        # Therefore, we perform the filtering in the reversed sorted order of\n        # the substituted strings. If, however, the strings are identical (e.g.\n        # both CC and FC are set using realpath), the filtering is done\n        # according to the order in compiler_vars. To achieve that, we populate\n        # the following array with tuples of three elements: path to the\n        # wrapper, negated index of the variable in compiler_vars, path to the\n        # real compiler. This way, the reversed sorted order of the resulting\n        # array is the order of replacements that we need.\n        replacements = []\n\n        for idx, (env_var, compiler_path) in enumerate(compiler_vars):\n            if env_var in os.environ and compiler_path is not None:\n                # filter spack wrapper and links to spack wrapper in case\n                # build system runs realpath\n                wrapper = os.environ[env_var]\n                for wrapper_path in (wrapper, os.path.realpath(wrapper)):\n                    replacements.append((wrapper_path, -idx, compiler_path))\n\n        for wrapper_path, _, compiler_path in sorted(replacements, reverse=True):\n            x.filter(wrapper_path, compiler_path, **filter_kwargs)\n\n        # Remove this linking flag if present (it turns RPATH into RUNPATH)\n        x.filter(\"{0}--enable-new-dtags\".format(pkg.compiler.linker_arg), \"\", **filter_kwargs)\n\n        # NAG compiler is usually mixed with GCC, which has a different\n        # prefix for linker arguments.\n        if pkg.compiler.name == \"nag\":\n            x.filter(\"-Wl,--enable-new-dtags\", \"\", **filter_kwargs)\n\n    spack.builder.run_after(after)(_filter_compiler_wrappers_impl)\n", "path": "lib/spack/spack/mixins.py"}]}