Hacktoberfest 2026：维护者为十月标记出来的 issue，仍然开放、适合新手。 浏览 Hacktoberfest issue

Windows CI: a 1-row netCDF grid is read back with a collapsed y range (test/grdtrend/trend_xy_plot.sh)

未关闭
  • 哪里不对？
#9,261 4 条评论 0 个 reaction 已指派 0 人 在 GitHub 查看

维护者通常 1 天内回复

还没有人认领这个 Issue。

评估

难度
4/5
预计耗时
3-5 天
新手友好度
15/100
Issue 类型
缺陷
描述清晰度
基本清楚
活跃度
活跃
技术栈
c
领域
data, testing

调研方向

The bug is in gmtnc_grd_info in src/gmt_nc.c, where the y range of a 1-row grid comes only from actual_range (around lines 774-803). Reproduce with gmt grdmath to make row.grd, then gmt grdinfo -C row.grd, and compare with test/grdtrend/trend_xy_plot.sh. Done means a 1-row grid reads back with y range -0.2/0.2 on the Windows CI build, without the #pragma optimize workaround. The maintainers have not chosen a fix yet, so confirm the approach first.

由索引模型根据 Issue 内容生成。

描述

bug

I asked Claude to look for a solution to the failure of this test in the Windows CI, and this is its analysis. I am posting it to ask what you prefer to do about it.

test/grdtrend/trend_xy_plot.sh fails only in the Windows CI (MSVC 14.51.36231, Visual Studio 2026 image, Release /O2 /Ob2 /DNDEBUG, vcpkg netCDF 4.9.3): grdtrend prints Grid y increment <= 0.0 [data.grd] and crashes. I would like to ask what you prefer for this one, because I could not find the root cause.

What fails. The grid written by grdmath is valid and reads fine on Linux and through GDAL, but on the Windows CI the same call reads a 6x1 grid with y range 0/0:

gmt grdmath -R-1.2/1.2/-0.2/0.2 -I0.4 -r 0.5 X ADD X X MUL ADD X 3 POW ADD = row.grd
gmt grdinfo -C row.grd
  • good: row.grd -1.2 1.2 -0.2 0.2 -0.5 3.5 0.4 0.4 6 1 1 0
  • CI: row.grd -1.2 1.2 0 0 -0.5 3.5 0.4 0 6 0 1 0 (y range 0/0, y_inc 0, 0 rows)

It fails when the test runs alone (no -j4), and also outside the test (https://github.com/GenericMappingTools/gmt/actions/runs/38145255398). A 1-column x 6-row grid reads fine, GDAL reads y#actual_range={-0.2,0.2} fine, and the only netcdf.dll copies on PATH are vcpkg's. For a 1-row grid the y range comes only from actual_range (there is no usable y vector), in the y block of gmtnc_grd_info (src/gmt_nc.c, around lines 774-803); the x block has the same structure.

What I tried.

  • Any debug print inside gmtnc_grd_info, even a passive one, makes the failure disappear.
  • #pragma optimize("", off) around gmtnc_grd_info only, with nothing else changed, makes the test pass (https://github.com/GenericMappingTools/gmt/actions/runs/38176185877).
  • ASAN and UBSAN builds on Linux find nothing in this path, and I found no undefined behaviour by reading it.
  • A gmt 6.8.0_f6039ec build from September on a Windows 10 PC reads the grid correctly, but I don't know its toolset or flags. gmtnc_grd_info is identical to the one in master.

So it looks like an optimizer problem (compiler bug or an undefined behaviour that /O2 exploits), but I could not prove either.

Questions.

  1. Does anyone with a local MSVC 14.50 or 14.51 build reproduce the grdinfo output above?
  2. The 6.7.0 Windows binaries were linked with MSVC 14.50. Does the official 6.7.0 binary read the 1-row grid correctly? If not, users are affected and not only the test.
  3. How do you prefer to handle it: (a) the #pragma optimize change above, guarded by _MSC_VER (I have a 6-line patch ready), (b) mark the test with # GMT_KNOWN_FAILURE_WINDOWS, or (c) something else?

Reviewed with Claude Opus 5.5 (read-only review of the analysis). Written with Claude Sonnet 5.5.

主要语言
C
星标
985
派生
414
平均合并
22 小时 51 分钟
30 天内合并 PR
35

环境准备

从这里开始

  1. 先读完整个 Issue，再读项目的贡献指南。
  2. 在 Issue 下留言说明你要接手 —— 这能避免两个人做同样的事。
  3. Fork 仓库，在一个分支上完成修改。
  4. 提交 Pull Request，并在描述里引用这个 Issue 编号。

GenericMappingTools/gmt 的其他 Issue

查看 GenericMappingTools/gmt 的全部 Issue

相似的 Issue

更多 C Issue

把新 issue 发到你的邮箱

精选适合新手参与的 GitHub issue 摘要。