parser: improve error message for missing } in attrset

Change-Id: I2846dbd8d0c1beb23c885a2d6d388a4f6a6a6964

lix/libexpr/parser/grammar.hh

@@ -209,6 +209,7 @@ namespace d {
     namespace t {
         struct inherit : one<';'> { };
         struct binding : one<';'> { };
+        struct attrs : one<'}'> { };
     }
 }
 
@@ -401,7 +402,7 @@ struct _attr {
     struct expr : semantic, seq<
         TAO_PEGTL_STRING("${"), seps,
         must<grammar::v1::expr>, seps,
-        must<one<'}'>>
+        must<d::t::attrs>
     > {};
 };
 struct attr : _attr, sor<
@@ -505,7 +506,7 @@ struct _expr {
         Init...,
         OpenMod<one<'{'>>, seps,
         bindings, seps,
-        must<one<'}'>>
+        must<d::t::attrs>
     > {};
 
     struct select;

lix/libexpr/parser/parser-impl1.inc.cc

@@ -58,6 +58,7 @@ error_message_for(grammar::v1::t::kw_else) = "expecting 'else'";
 error_message_for(grammar::v1::t::kw_in) = "expecting 'in'";
 error_message_for(grammar::v1::d::t::binding) = "expecting ';' to end binding";
 error_message_for(grammar::v1::d::t::inherit) = "expecting ';' to end 'inherit' bindings";
+error_message_for(grammar::v1::d::t::attrs) = "expecting '}' to end attribute set";
 
 struct SyntaxErrors
 {

tests/functional2/lang/assets/test_lang_infra/runner_ef.err.exp

@@ -1,4 +1,4 @@
-error: syntax error, unexpected end of file, expecting '}'
+error: syntax error, unexpected end of file, expecting '}' to end attribute set
        at /pwd/in.nix:1:2:
             1| {
              |  ^

tests/functional2/lang/assets/test_lang_infra/runner_pf.err.exp

@@ -1,4 +1,4 @@
-error: syntax error, unexpected end of file, expecting '}'
+error: syntax error, unexpected end of file, expecting '}' to end attribute set
        at /pwd/in.nix:1:2:
             1| {
              |  ^

tests/functional2/lang/attrs/in-unterminated.nix

@@ -0,0 +1,2 @@
+{
+  a = "b";

tests/functional2/lang/attrs/parse-fail-unterminated.err.exp

@@ -0,0 +1,5 @@
+error: syntax error, unexpected end of file, expecting '}' to end attribute set
+       at /pwd/in.nix:3:1:
+            2|   a = "b";
+            3|
+             | ^