fix: deduplicate prefixes for unparsed text properties

src/lib.rs

@@ -17551,6 +17551,208 @@ mod tests {
     );
   }
 
+  #[test]
+  fn test_unparsed_text_decoration_prefixes() {
+    let targets = Browsers {
+      safari: Some((14 << 16) | (1 << 8)),
+      ..Browsers::default()
+    };
+    let expected = indoc! {"
+      .link {
+        -webkit-text-decoration: underline var(--accent);
+        text-decoration: underline var(--accent);
+      }
+    "};
+
+    for source in [
+      indoc! {"
+        .link {
+          text-decoration: underline var(--accent);
+        }
+      "},
+      indoc! {"
+        .link {
+          -webkit-text-decoration: underline var(--accent);
+          text-decoration: underline var(--accent);
+        }
+      "},
+      indoc! {"
+        .link {
+          text-decoration: underline var(--accent);
+          -webkit-text-decoration: underline var(--accent);
+        }
+      "},
+      indoc! {"
+        .link {
+          -webkit-text-decoration: underline var(--accent);
+          -webkit-text-decoration: underline var(--accent);
+          text-decoration: underline var(--accent);
+        }
+      "},
+      indoc! {"
+        .link {
+          -webkit-text-decoration: underline var(--accent);
+          /* An ordinary comment does not prevent deduplication. */
+          text-decoration: underline var(--accent);
+        }
+      "},
+    ] {
+      prefix_test(source, expected, targets);
+    }
+
+    // An already-prefixed result must not grow when minified again.
+    prefix_test(expected, expected, targets);
+
+    let important = indoc! {"
+      .link {
+        -webkit-text-decoration: underline var(--accent) !important;
+        text-decoration: underline var(--accent) !important;
+      }
+    "};
+    prefix_test(important, important, targets);
+
+    let fallback = indoc! {"
+      .link {
+        -webkit-text-decoration: underline var(--accent, red);
+        text-decoration: underline var(--accent, red);
+      }
+    "};
+    prefix_test(fallback, fallback, targets);
+
+    // Explicit prefixes are retained even if the targets do not require them.
+    prefix_test(
+      expected,
+      expected,
+      Browsers {
+        chrome: Some(120 << 16),
+        ..Browsers::default()
+      },
+    );
+    test(expected, expected);
+  }
+
+  #[test]
+  fn test_unparsed_text_prefix_boundaries() {
+    let targets = Browsers {
+      safari: Some((14 << 16) | (1 << 8)),
+      ..Browsers::default()
+    };
+
+    for source in [
+      // Different values must retain their vendor-specific fallbacks.
+      indoc! {"
+        .link {
+          -webkit-text-decoration: var(--old);
+          -webkit-text-decoration: var(--new);
+          text-decoration: var(--new);
+        }
+      "},
+      // Normal and important declarations must not share prefix state.
+      indoc! {"
+        .link {
+          -webkit-text-decoration: var(--decoration);
+          -webkit-text-decoration: var(--decoration) !important;
+          text-decoration: var(--decoration) !important;
+        }
+      "},
+      // An intervening parsed longhand prevents moving the later shorthand.
+      indoc! {"
+        .link {
+          -webkit-text-decoration: var(--decoration);
+          text-decoration: var(--decoration);
+          text-decoration-color: red;
+          -webkit-text-decoration: var(--decoration);
+          text-decoration: var(--decoration);
+        }
+      "},
+      // An unparsed longhand is also a barrier, even with identical tokens.
+      indoc! {"
+        .link {
+          -webkit-text-decoration: var(--value);
+          text-decoration: var(--value);
+          -webkit-text-decoration-color: var(--value);
+          text-decoration-color: var(--value);
+          -webkit-text-decoration: var(--value);
+          text-decoration: var(--value);
+        }
+      "},
+      // Prefix state cannot cross rule or conditional boundaries.
+      indoc! {"
+        .link {
+          -webkit-text-decoration: var(--decoration);
+          text-decoration: var(--decoration);
+        }
+
+        @media print {
+          .link {
+            -webkit-text-decoration: var(--decoration);
+            text-decoration: var(--decoration);
+          }
+        }
+      "},
+    ] {
+      prefix_test(source, source, targets);
+    }
+
+    // Prefix-only input must not acquire an unprefixed declaration.
+    let prefixed = indoc! {"
+      .link {
+        -webkit-text-decoration: var(--decoration);
+      }
+    "};
+    prefix_test(prefixed, prefixed, targets);
+  }
+
+  #[test]
+  fn test_unparsed_text_longhand_prefixes() {
+    let source = indoc! {"
+      .link {
+        -webkit-text-decoration-line: var(--value);
+        text-decoration-line: var(--value);
+        -webkit-text-decoration-style: var(--value);
+        text-decoration-style: var(--value);
+        -webkit-text-decoration-color: var(--value);
+        text-decoration-color: var(--value);
+        text-decoration-thickness: var(--value);
+      }
+    "};
+    prefix_test(
+      source,
+      source,
+      Browsers {
+        safari: Some(12 << 16),
+        ..Browsers::default()
+      },
+    );
+  }
+
+  #[test]
+  fn test_unparsed_text_emphasis_prefixes() {
+    let targets = Browsers {
+      chrome: Some(80 << 16),
+      ..Browsers::default()
+    };
+    let source = indoc! {"
+      .label {
+        -webkit-text-emphasis: filled var(--mark);
+        text-emphasis: filled var(--mark);
+      }
+    "};
+    prefix_test(source, source, targets);
+
+    let longhands = indoc! {"
+      .label {
+        -webkit-text-emphasis-style: var(--value);
+        text-emphasis-style: var(--value);
+        -webkit-text-emphasis-color: var(--value);
+        text-emphasis-color: var(--value);
+        -webkit-text-emphasis-position: var(--value);
+        text-emphasis-position: var(--value);
+      }
+    "};
+    prefix_test(longhands, longhands, targets);
+  }
+
   #[test]
   fn test_text_emphasis() {
     minify_test(".foo { text-emphasis-style: none }", ".foo{text-emphasis-style:none}");

src/properties/text.rs

@@ -1193,16 +1193,29 @@ impl<'i> PropertyHandler<'i> for TextDecorationHandler<'i> {
           _ => dest.push(property.clone()),
         }
       }
-      Unparsed(val) if is_text_decoration_property(&val.property_id) => {
-        self.finalize(dest, context);
-        let mut unparsed = val.get_prefixed(context.targets, Feature::TextDecoration);
-        context.add_unparsed_fallbacks(&mut unparsed);
-        dest.push(Property::Unparsed(unparsed))
-      }
-      Unparsed(val) if is_text_emphasis_property(&val.property_id) => {
+      Unparsed(val) => {
+        let feature = if is_text_decoration_property(&val.property_id) {
+          Feature::TextDecoration
+        } else if is_text_emphasis_property(&val.property_id) {
+          Feature::TextEmphasis
+        } else {
+          return false;
+        };
+
         self.finalize(dest, context);
-        let mut unparsed = val.get_prefixed(context.targets, Feature::TextEmphasis);
+        let mut unparsed = val.get_prefixed(context.targets, feature);
         context.add_unparsed_fallbacks(&mut unparsed);
+
+        // Combine adjacent identical values after adding prefixes and fallbacks.
+        // Only inspect the last declaration so intervening longhands retain their order.
+        if let Some(Property::Unparsed(previous)) = dest.last_mut() {
+          let prefix = unparsed.property_id.prefix();
+          if previous.property_id.with_prefix(prefix) == unparsed.property_id && previous.value == unparsed.value {
+            previous.property_id.add_prefix(prefix);
+            return true;
+          }
+        }
+
         dest.push(Property::Unparsed(unparsed))
       }
       _ => return false,