Coerce numbers in for ranges if possible

Author: mgreter

src/ast_values.cpp

@@ -1096,6 +1096,14 @@ namespace Sass {
     return this;
   }
 
+  Number* Number::coerce(Logger& logger, Number& lhs)
+  {
+    if (this->Units::operator==(lhs)) return this;
+    double factor = getUnitConversionFactor(lhs);
+    if (factor == 0.0) throw Exception::UnitMismatch(logger, lhs, *this);
+    return SASS_MEMORY_NEW(Number, pstate(), value() * factor, lhs);
+  }
+
   /////////////////////////////////////////////////////////////////////////
   // Implement delayed value fetcher
   /////////////////////////////////////////////////////////////////////////

src/ast_values.hpp

@@ -399,6 +399,8 @@ namespace Sass {
       value_ *= this->Units::normalize();
     }
 
+    Number* coerce(Logger& logger, Number& rhs);
+
     // Implement delayed value fetcher
     Value* withoutSlash() override final;
 

src/eval.cpp

@@ -1470,7 +1470,7 @@ namespace Sass {
   }
 
   /*
-   
+
   /// Whether this node has a visible sibling after it.
   bool get hasFollowingSibling {
     if (_parent == null) return false;
@@ -2004,6 +2004,11 @@ namespace Sass {
     ValueObj high = f->upper_bound()->accept(this);
     NumberObj sass_start = low->assertNumber(logger456, "");
     NumberObj sass_end = high->assertNumber(logger456, "");
+    // Support compatible unit types (e.g. cm to mm)
+    sass_end = sass_end->coerce(logger456, sass_start);
+    // Can only use integer ranges
+    sass_start->assertInt(logger456);
+    sass_end->assertInt(logger456);
     // check if units are valid for sequence
     if (sass_start->unit() != sass_end->unit()) {
       callStackFrame csf(logger456, f->pstate());