Make SymbolNode#value_loc non-optional

Sort of a followup for 929aec1

It changed the value for `:''` into nil/null, which is a bit inconvenient.
For syntax-valid code I expect it to always be present.

It's also inconsistent with `StringNode`. In effect,
this reverts the snapshots changes and the two changes
in ruby for the ripper/parser compiler.

Author: Earlopain

config.yml

@@ -4553,7 +4553,7 @@ nodes:
       - name: opening_loc
         type: location?
       - name: value_loc
-        type: location?
+        type: location
       - name: closing_loc
         type: location?
       - name: unescaped

lib/prism/translation/parser/compiler.rb

@@ -165,13 +165,13 @@ def visit_assoc_node(node)
           else
             parts =
               if key.is_a?(SymbolNode)
-                value_loc = key.value_loc
-                if value_loc.nil?
+                value = key.value
+                if value == ""
                   []
-                elsif value_loc.slice.include?("\n")
-                  string_nodes_from_line_continuations(key.unescaped, value_loc.slice, value_loc.start_offset, key.opening)
+                elsif value.include?("\n")
+                  string_nodes_from_line_continuations(key.unescaped, value, key.value_loc.start_offset, key.opening)
                 else
-                  [builder.string_internal([key.unescaped, srange(value_loc)])]
+                  [builder.string_internal([key.unescaped, srange(key.value_loc)])]
                 end
               else
                 visit_all(key.parts)
@@ -1775,7 +1775,7 @@ def visit_symbol_node(node)
             end
           else
             parts =
-              if node.value_loc.nil?
+              if node.value == ""
                 []
               elsif node.value.include?("\n")
                 string_nodes_from_line_continuations(node.unescaped, node.value, node.value_loc.start_offset, node.opening)

lib/prism/translation/ripper.rb

@@ -3840,12 +3840,14 @@ def visit_super_node(node)
       # ^^^^
       def visit_symbol_node(node)
         with_string_bounds(node) do
-          if node.value_loc.nil?
-            bounds(node.location)
-            on_dyna_symbol(on_string_content)
-          elsif (opening = node.opening)&.match?(/^%s|['"]:?$/)
+          if (opening = node.opening)&.match?(/^%s|['"]:?$/)
             bounds(node.value_loc)
-            content = on_string_add(on_string_content, on_tstring_content(node.value))
+            content = on_string_content
+
+            if !(value = node.value).empty?
+              content = on_string_add(content, on_tstring_content(value))
+            end
+
             bounds(node.location)
             on_dyna_symbol(content)
           elsif (closing = node.closing) == ":"

rbi/generated/prism/dsl.rbi

@@ -447,7 +447,7 @@
         │   │       │   @ SymbolNode (location: (30,2)-(30,5))
         │   │       │   ├── flags: static_literal
         │   │       │   ├── opening_loc: (30,2)-(30,3) = "\""
-        │   │       │   ├── value_loc: ∅
+        │   │       │   ├── value_loc: (1,0)-(1,0) = ""
         │   │       │   ├── closing_loc: (30,3)-(30,5) = "\":"
         │   │       │   └── unescaped: ""
         │   │       ├── value:

rbi/generated/prism/node.rbi

@@ -8,6 +8,6 @@
         └── @ SymbolNode (location: (1,0)-(1,3))
             ├── flags: newline, static_literal, forced_us_ascii_encoding
             ├── opening_loc: (1,0)-(1,2) = ":'"
-            ├── value_loc: ∅
+            ├── value_loc: (1,2)-(1,2) = ""
             ├── closing_loc: (1,2)-(1,3) = "'"
             └── unescaped: ""

sig/generated/prism/dsl.rbs

@@ -129,7 +129,7 @@
         │   │       └── @ SymbolNode (location: (17,4)-(20,0))
         │   │           ├── flags: static_literal, forced_us_ascii_encoding
         │   │           ├── opening_loc: (17,4)-(18,0) = "%s\n"
-        │   │           ├── value_loc: ∅
+        │   │           ├── value_loc: (18,0)-(18,0) = ""
         │   │           ├── closing_loc: (19,0)-(20,0) = "\n"
         │   │           └── unescaped: ""
         │   ├── closing_loc: ∅