[analyzer] fuse auto-generated vars of `haxe.extern.AsVar`

if were created out of user-defined vars

src/generators/genphp7.ml

@@ -2295,7 +2295,7 @@ class code_writer (ctx:php_generator_context) hx_type_path php_name =
 				| TTypeExpr (TClassDecl tcls) ->
 					self#write (self#use_t (TInst (tcls, [])))
 				| _ ->
-					if is_string type_expr then
+					if is_string (reveal_expr type_expr) then
 						self#write_expr type_expr
 					else begin
 						self#write "(";
@@ -2368,6 +2368,19 @@ class code_writer (ctx:php_generator_context) hx_type_path php_name =
 				| [] -> self#write_assoc_array_decl []
 				| { eexpr = TObjectDecl fields } :: [] -> self#write_assoc_array_decl fields
 				| _ -> ctx.pgc_common.error "php.Syntax.assocDecl() accepts object declaration only." self#pos
+		(**
+			Writes `e` to be used as a field access.
+			If `e` is a constant string, writes the constant without quotes.
+			Otherwise writes `{e}`
+		*)
+		method write_syntax_field_expr field_expr =
+			match reveal_expr field_expr with
+				| { eexpr = TConst (TString method_name) } ->
+					self#write method_name
+				| _ ->
+					self#write "{";
+					self#write_expr field_expr;
+					self#write "}"
 		(**
 			Writes a call to instance method (for `php.Syntax.call()`)
 		*)
@@ -2375,9 +2388,9 @@ class code_writer (ctx:php_generator_context) hx_type_path php_name =
 			match args with
 				| obj_expr :: method_expr :: args ->
 					self#write_expr obj_expr;
-					self#write "->{";
-					self#write_expr method_expr;
-					self#write "}(";
+					self#write "->";
+					self#write_syntax_field_expr method_expr;
+					self#write "(";
 					write_args self#write (fun e -> self#write_expr e) args;
 					self#write ")"
 				| _ -> fail self#pos
@@ -2388,9 +2401,9 @@ class code_writer (ctx:php_generator_context) hx_type_path php_name =
 			match args with
 				| type_expr :: method_expr :: args ->
 					self#write_type type_expr;
-					self#write "::{";
-					self#write_expr method_expr;
-					self#write "}(";
+					self#write "::";
+					self#write_syntax_field_expr method_expr;
+					self#write "(";
 					write_args self#write (fun e -> self#write_expr e) args;
 					self#write ")"
 				| _ -> fail self#pos
@@ -2401,9 +2414,8 @@ class code_writer (ctx:php_generator_context) hx_type_path php_name =
 			match args with
 				| obj_expr :: field_expr :: [] ->
 					self#write_expr obj_expr;
-					self#write "->{";
-					self#write_expr field_expr;
-					self#write "}"
+					self#write "->";
+					self#write_syntax_field_expr field_expr;
 				| _ -> fail self#pos
 		(**
 			Writes field access for writing (for `php.Syntax.setField()`)

src/optimization/analyzerTexpr.ml

@@ -709,7 +709,10 @@ module Fusion = struct
 			let b = num_uses <= 1 &&
 			        num_writes = 0 &&
 			        can_be_used_as_value &&
-					not (ExtType.has_variable_semantics v.v_type) &&
+					not (
+						ExtType.has_variable_semantics v.v_type &&
+						(match e.eexpr with TLocal { v_kind = VUser _ } -> false | _ -> true)
+					) &&
 			        (is_compiler_generated || config.optimize && config.fusion && config.user_var_fusion && not has_type_params)
 			in
 			if config.fusion_debug then begin