René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"[Bug]: Can not fallback to `kpsewhich` when `luatex` does not work","articleBody":"### Bug summary\n\nHi, I found that the function `find_tex_file` in `dviread.py` can not fallback to using `kpsewhich` when `luatex` does not work. I think the problem is caused by the fact that my `glibc` is too old, _i.e._, when I run `luatex --luaonly`, I get:\n\n```bash\nluatex: /lib64/libc.so.6: version `GLIBC_2.28' not found (required by luatex)\n```\n\nLaTeX version: pdfTeX 3.141592653-2.6-1.40.29 (TeX Live 2026)\n\n### Code for reproduction\n\n```Python\n## matplotlib\nimport matplotlib\nmatplotlib.use('Agg')\nmatplotlib.rcParams['text.latex.preamble'] = r'\\usepackage{amsmath}';\nmatplotlib.rc('text', usetex = True)\nfrom matplotlib import pyplot as py\n\nxs = [1.0, 2.0, 3.0]\nys = [1.0, 2.0, 3.0]\naxs = [py.subplot(1, 1, 1)]\naxs[0].plot(xs, ys, color = 'dodgerblue')\nx_label = r'$\\Delta, \\Theta, \\Xi, \\Pi, \\Sigma, \\Upsilon, \\Phi, \\Psi, \\Omega, \\Gamma$'\ny_label = r'$\\delta, \\theta, \\xi, \\pi, \\sigma, \\upsilon, \\phi, \\psi, \\omega, \\gamma$'\naxs[0].set_xlabel(x_label, size = 20)\naxs[0].set_ylabel(y_label, size = 20)\npy.tight_layout()\nname = './test.pdf'\npy.savefig(name)\npy.close()\n```\n\n### Actual outcome\n\n```bash\nTraceback (most recent call last):\n  File \"/public/home/zhouyy/test/test.py\", line 16, in \u003cmodule\u003e\n    py.tight_layout()\n  File \"/public/home/zhouyy/packages/miniforge3/lib/python3.12/site-packages/matplotlib/pyplot.py\", line 2992, in tight_layout\n    gcf().tight_layout(pad=pad, h_pad=h_pad, w_pad=w_pad, rect=rect)\n  File \"/public/home/zhouyy/packages/miniforge3/lib/python3.12/site-packages/matplotlib/figure.py\", line 3665, in tight_layout\n    engine.execute(self)\n  File \"/public/home/zhouyy/packages/miniforge3/lib/python3.12/site-packages/matplotlib/layout_engine.py\", line 188, in execute\n    kwargs = get_tight_layout_figure(\n             ^^^^^^^^^^^^^^^^^^^^^^^^\n  File \"/public/home/zhouyy/packages/miniforge3/lib/python3.12/site-packages/matplotlib/_tight_layout.py\", line 266, in get_tight_layout_figure\n    kwargs = _auto_adjust_subplotpars(fig, renderer,\n             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n  File \"/public/home/zhouyy/packages/miniforge3/lib/python3.12/site-packages/matplotlib/_tight_layout.py\", line 82, in _auto_adjust_subplotpars\n    bb += [martist._get_tightbbox_for_layout_only(ax, renderer)]\n           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n  File \"/public/home/zhouyy/packages/miniforge3/lib/python3.12/site-packages/matplotlib/artist.py\", line 1485, in _get_tightbbox_for_layout_only\n    return obj.get_tightbbox(*args, **{**kwargs, \"for_layout_only\": True})\n           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n  File \"/public/home/zhouyy/packages/miniforge3/lib/python3.12/site-packages/matplotlib/axes/_base.py\", line 4740, in get_tightbbox\n    ba = martist._get_tightbbox_for_layout_only(axis, renderer)\n         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n  File \"/public/home/zhouyy/packages/miniforge3/lib/python3.12/site-packages/matplotlib/artist.py\", line 1485, in _get_tightbbox_for_layout_only\n    return obj.get_tightbbox(*args, **{**kwargs, \"for_layout_only\": True})\n           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n  File \"/public/home/zhouyy/packages/miniforge3/lib/python3.12/site-packages/matplotlib/axis.py\", line 1427, in get_tightbbox\n    self._update_label_position(renderer)\n  File \"/public/home/zhouyy/packages/miniforge3/lib/python3.12/site-packages/matplotlib/axis.py\", line 2615, in _update_label_position\n    bboxes, bboxes2 = self._get_tick_boxes_siblings(renderer=renderer)\n                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n  File \"/public/home/zhouyy/packages/miniforge3/lib/python3.12/site-packages/matplotlib/axis.py\", line 2403, in _get_tick_boxes_siblings\n    tlb, tlb2 = axis._get_ticklabel_bboxes(ticks_to_draw, renderer)\n                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n  File \"/public/home/zhouyy/packages/miniforge3/lib/python3.12/site-packages/matplotlib/axis.py\", line 1404, in _get_ticklabel_bboxes\n    return ([tick.label1.get_window_extent(renderer)\n             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n  File \"/public/home/zhouyy/packages/miniforge3/lib/python3.12/site-packages/matplotlib/text.py\", line 1076, in get_window_extent\n    bbox, _, _ = self._get_layout(self._renderer)\n                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n  File \"/public/home/zhouyy/packages/miniforge3/lib/python3.12/site-packages/matplotlib/text.py\", line 465, in _get_layout\n    _, h, min_descent = _get_text_metrics_with_cache(\n                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n  File \"/public/home/zhouyy/packages/miniforge3/lib/python3.12/site-packages/matplotlib/text.py\", line 59, in _get_text_metrics_with_cache\n    return get_text_metrics(text, fontprop.copy(), ismath, dpi)\n           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n  File \"/public/home/zhouyy/packages/miniforge3/lib/python3.12/site-packages/matplotlib/text.py\", line 125, in _text_metrics\n    return local_renderer.get_text_width_height_descent(text, fontprop, ismath)\n           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n  File \"/public/home/zhouyy/packages/miniforge3/lib/python3.12/site-packages/matplotlib/backends/backend_agg.py\", line 256, in get_text_width_height_descent\n    return super().get_text_width_height_descent(s, prop, ismath)\n           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n  File \"/public/home/zhouyy/packages/miniforge3/lib/python3.12/site-packages/matplotlib/backend_bases.py\", line 589, in get_text_width_height_descent\n    return self.get_texmanager().get_text_width_height_descent(\n           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n  File \"/public/home/zhouyy/packages/miniforge3/lib/python3.12/site-packages/matplotlib/texmanager.py\", line 372, in get_text_width_height_descent\n    page, = dvi\n    ^^^^^\n  File \"/public/home/zhouyy/packages/miniforge3/lib/python3.12/site-packages/matplotlib/dviread.py\", line 278, in __iter__\n    while self._read():\n          ^^^^^^^^^^^^\n  File \"/public/home/zhouyy/packages/miniforge3/lib/python3.12/site-packages/matplotlib/dviread.py\", line 360, in _read\n    raise self._missing_font.to_exception()\nFileNotFoundError: Matplotlib's TeX implementation searched for a file named 'cmss10.tfm' in your texmf tree, but could not find it\n```\n\n### Expected outcome\n\nThe expected outcome can be achieved by commenting out the following lines and manually set `lk` to `None` in function `find_tex_file` in `dviread.py`:\n\n```python\n    # try:\n    #     lk = _LuatexKpsewhich()\n    # except (FileNotFoundError, OSError):\n    #     lk = None  # Fallback to directly calling kpsewhich, as below.\n    lk = None\n```\n\nBut this has caused a further issue: `\\Gamma` (and only `\\Gamma`, see the _x_-axis label) can not be rendered properly.\n\n[test.pdf](https://github.com/user-attachments/files/29592070/test.pdf)\n\n### Additional information\n\n_No response_\n\n### Operating system\n\nLinux 3.10.0-1160.el7.x86_64\n\n### Matplotlib Version\n\n3.11.0\n\n### Matplotlib Backend\n\nAgg\n\n### Python version\n\n3.12.12\n\n### Jupyter version\n\n_No response_\n\n### Installation\n\npip","author":{"url":"https://github.com/zhyiyu","@type":"Person","name":"zhyiyu"},"datePublished":"2026-07-02T09:52:41.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":2},"url":"https://github.com/31983/matplotlib/issues/31983"}