[db] fix name assignment

Address issue lualatex#356

The DejaVu Family needs stricter handling of fallback choices so we take
the font’s avertised width into consideration. This used to be easier
with the old loader since it had some decent heuristics in place for the
more or less reliable “fontstyle_name”.

src/luaotfload-database.lua

@@ -2537,6 +2537,7 @@ end
 
 local bold_spectrum_low  = 501 --- 500 is medium, 900 heavy/black
 local bold_weight        = 700
+local normal_width       = 5
 
 local pick_style
 local pick_fallback_style
@@ -2569,13 +2570,15 @@ do
         local style
         if typographicsubfamily then
             style = choose_exact (typographicsubfamily)
+            if style then return style end
         elseif subfamily then
             style = choose_exact (subfamily)
+            if style then return style end
         end
-        return style
+        return false
     end
 
-    pick_fallback_style = function (italicangle, weight, pfmweight)
+    pick_fallback_style = function (italicangle, pfmweight, width)
         --[[--
             More aggressive, but only to determine bold faces.
             Note: Before you make this test more inclusive, ensure
@@ -2586,7 +2589,8 @@ do
             treating weights > 500 as bold or allowing synonyms like
             “heavy”, “black”.
         --]]-- 
-        if pfmweight == bold_weight then --- bold spectrum matches
+        if width == normal_width and pfmweight == bold_weight then
+            --- bold spectrum matches
             if italicangle == 0 then
                 return "b"
             end
@@ -2602,6 +2606,7 @@ do
                               subfamily,
                               italicangle,
                               weight,
+                              width,
                               pfmweight)
         local plausible_weight = false
         --[[--
@@ -2611,17 +2616,32 @@ do
           oversimplifying classification into only three styles (r, i,
           b, bi).
         --]]--
-
         if italicangle == 0 then
-            if     pfmweight == 400                    then plausible_weight = true
-            elseif weight and regular_synonym [weight] then plausible_weight = true end
+            if pfmweight == 400 then
+                --[[--
+                  Some fonts like Dejavu advertise an undistinguished
+                  regular and a “condensed” version with the same
+                  weight whilst also providing the style info in the
+                  typographic subfamily instead of the subfamily (i. e.
+                  the converse of what Adobe’s doing). The only way to
+                  weed out the undesired pseudo-regular shape is to
+                  peek at its advertised width (4 vs. 5).
+                --]]--
+                if width then
+                    plausible_weight = width == normal_width
+                else
+                    plausible_weight = true
+                end
+            elseif weight and regular_synonym [weight] then
+                plausible_weight = true
+            end
         end
 
         if plausible_weight then
-            if typographicsubfamily  and regular_synonym [typographicsubfamily]
-            or subfamily             and regular_synonym [subfamily]
-            then
-                return "r"
+            if subfamily then
+                if regular_synonym [subfamily] then return "r" end
+            elseif typographicsubfamily then
+                if regular_synonym [typographicsubfamily] then return "r" end
             end
         end
         return false
@@ -2656,6 +2676,7 @@ local pull_values = function (entry)
     entry.italicangle       = style.italicangle
     entry.size              = style.size
     entry.weight            = style.weight
+    entry.width             = style.width
     entry.pfmweight         = style.pfmweight
 
     if config.luaotfload.db.strip == true then
@@ -2715,6 +2736,7 @@ local collect_families = function (mappings)
         local typographicsubfamily = entry.typographicsubfamily
         local subfamily            = entry.subfamily
         local weight               = entry.weight
+        local width                = entry.width
         local pfmweight            = entry.pfmweight
         local italicangle          = entry.italicangle
         local modifier             = pick_style (typographicsubfamily, subfamily)
@@ -2724,11 +2746,12 @@ local collect_families = function (mappings)
                                       subfamily,
                                       italicangle,
                                       weight,
+                                      width,
                                       pfmweight)
         end
 
         if not modifier then
-            modifier = pick_fallback_style (italicangle, weight, pfmweight)
+            modifier = pick_fallback_style (italicangle, pfmweight, width)
         end
 
         if modifier then