Don’t respect fr units for overconstrained sizes

tests/layout/test_grid.py

@@ -509,6 +509,37 @@ def test_grid_shorthand_auto_flow_rows_fr_size():
     assert article.width == 10
 
 
+@assert_no_logs
+def test_grid_template_fr_too_large():
+    page, = render_pages('''
+      <style>
+        @font-face { src: url(weasyprint.otf); font-family: weasyprint }
+        article {
+          display: grid;
+          font-family: weasyprint;
+          font-size: 2px;
+          grid-template-columns: 1fr 1fr;
+          line-height: 1;
+          width: 10px;
+        }
+      </style>
+      <article>
+        <div>a</div><div>bbb</div>
+      </article>
+    ''')
+    html, = page.children
+    body, = html.children
+    article, = body.children
+    div_a, div_b = article.children
+    assert div_a.position_x == 0
+    assert div_b.position_x == 4
+    assert div_a.position_y == div_b.position_y == 0
+    assert div_a.height == div_b.height == 2
+    assert div_a.width == 4
+    assert div_b.width == 6
+    assert article.width == 10
+
+
 def test_grid_shorthand_auto_flow_columns_none_dense():
     page, = render_pages('''
       <style>

weasyprint/layout/grid.py

@@ -510,12 +510,12 @@ def _resolve_tracks_sizes(sizing_functions, box_size, children_positions,
                 free_space -= distributed_free_space
     # TODO: Respect max-width/-height.
     # 1.4 Expand flexible tracks.
+    inflexible_tracks = set()
     if free_space is not None and free_space <= 0:
         # TODO: Respect min-content constraint.
         flex_fraction = 0
     elif free_space is not None:
         stop = False
-        inflexible_tracks = set()
         while not stop:
             leftover_space = free_space
             flex_factor_sum = 0
@@ -533,7 +533,8 @@ def _resolve_tracks_sizes(sizing_functions, box_size, children_positions,
                 if i not in inflexible_tracks and _is_fr(max_function):
                     if hypothetical_fr_size * max_function.value < sizes[0]:
                         inflexible_tracks.add(i)
-                        stop = False
+                        free_space -= sizes[0]
+                        stop = free_space > 0
         flex_fraction = hypothetical_fr_size
     else:
         flex_fraction = 0
@@ -549,7 +550,7 @@ def _resolve_tracks_sizes(sizing_functions, box_size, children_positions,
         # TODO: Respect min-* constraint.
     iterable = enumerate(zip(tracks_sizes, sizing_functions))
     for i, (sizes, (_, max_function)) in iterable:
-        if _is_fr(max_function):
+        if _is_fr(max_function) and i not in inflexible_tracks:
             if flex_fraction * max_function.value > sizes[0]:
                 if free_space is not None:
                     free_space -= flex_fraction * max_function.value