fix(papergrid): saturating_sub in calculate_indent to avoid underflow panic#586
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fix(papergrid): saturating_sub in calculate_indent to avoid underflow panic#586momomuchu wants to merge 1 commit into
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calculate_indent subtracted width from available without checking that available >= width. When a custom Dimension implementation reports a column width smaller than the actual content width, this underflows and panics with "attempt to subtract with overflow". Use saturating_sub in all three copies of calculate_indent (grid_basic, grid_not_spanned, grid_spanned). Fixes zhiburt#567
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calculate_indent()panics with "attempt to subtract with overflow" when a customDimension::get_widthreturns a width smaller than the content width, because it does an uncheckedavailable - width.The function is duplicated in three private grid modules, and all three had the same unchecked subtraction (peekable.rs:444, 985, 1861). Each now uses
available.saturating_sub(width). Clamping to 0 is the correct indent when content already exceeds the reported available width.Added regression tests driving a custom
Dimensionwhose width is less than the content width. They panic without the fix (at all three sites) and pass with it.cargo test -p papergridgreen, clippy and fmt clean.Note: the adjacent
rest_width = cell_width - line_widtha few lines above each site is intentionally left as-is. It is not affected by this bug:cell_widthisget_width(the max over the cell's lines) andline_widthis a single line's width, socell_width >= line_widthholds by construction.Closes #567