libexpr/parser: Use readable tokens in error messages instead of internal token names

Very low-hanging fruit for improving parser error messages.

src/libexpr/parser.y

@@ -3,7 +3,7 @@
 %define api.namespace { ::nix::parser }
 %define api.parser.class { BisonParser }
 %locations
-%define parse.error verbose
+%define parse.error detailed
 %defines
 /* %no-lines */
 %parse-param { void * scanner }
@@ -140,18 +140,41 @@ static Expr * makeCall(Exprs & exprs, PosIdx pos, Expr * fn, Expr * arg) {
 %type <Expr *> path_start
 %type <ToBeStringyExpr> string_parts string_attr
 %type <StringToken> attr
-%token <StringToken> ID
-%token <StringToken> STR IND_STR
-%token <NixInt> INT_LIT
-%token <NixFloat> FLOAT_LIT
-%token <StringToken> PATH HPATH SPATH PATH_END
-%token <StringToken> URI
-%token IF THEN ELSE ASSERT WITH LET IN_KW REC INHERIT EQ NEQ AND OR IMPL OR_KW
-%token PIPE_FROM PIPE_INTO /* <| and |> */
-%token DOLLAR_CURLY /* == ${ */
-%token IND_STRING_OPEN IND_STRING_CLOSE
-%token ELLIPSIS
-
+%token <StringToken> ID "identifier"
+%token <StringToken> STR "string"
+%token <StringToken> IND_STR "indented string"
+%token <NixInt> INT_LIT "integer"
+%token <NixFloat> FLOAT_LIT "floating-point literal"
+%token <StringToken> PATH "path"
+%token <StringToken> HPATH "'~/…' path"
+%token <StringToken> SPATH "'<…>' path"
+%token <StringToken> PATH_END "end of path"
+%token <StringToken> URI "URI"
+%token IF "'if'"
+%token THEN "'then'"
+%token ELSE "'else'"
+%token ASSERT "'assert'"
+%token WITH "'with'"
+%token LET "'let'"
+%token IN_KW "'in'"
+%token REC "'rec'"
+%token INHERIT "'inherit'"
+%token EQ "'=='"
+%token NEQ "'!='"
+%token LEQ "'<='"
+%token GEQ "'>='"
+%token UPDATE "'//'"
+%token CONCAT "'++'"
+%token AND "'&&'"
+%token OR "'||'"
+%token IMPL "'->'"
+%token OR_KW "'or'"
+%token PIPE_FROM "'<|'"
+%token PIPE_INTO "'|>'"
+%token DOLLAR_CURLY "'${'"
+%token IND_STRING_OPEN "start of an indented string"
+%token IND_STRING_CLOSE "end of an indented string"
+%token ELLIPSIS "'...'"
 
 %right IMPL
 %left OR

tests/functional/lang/parse-fail-unexpected-and.err.exp

@@ -0,0 +1,5 @@
+error: syntax error, unexpected '&&'
+       at «stdin»:1:1:
+            1| && true
+             | ^
+            2|

tests/functional/lang/parse-fail-unexpected-and.nix

@@ -0,0 +1 @@
+&& true

tests/functional/lang/parse-fail-unexpected-assert.err.exp

@@ -0,0 +1,5 @@
+error: syntax error, unexpected 'assert', expecting identifier or 'or' or '${' or '"'
+       at «stdin»:1:3:
+            1| a.assert
+             |   ^
+            2|

tests/functional/lang/parse-fail-unexpected-assert.nix

@@ -0,0 +1 @@
+a.assert

tests/functional/lang/parse-fail-unexpected-concat.err.exp

@@ -0,0 +1,5 @@
+error: syntax error, unexpected '++'
+       at «stdin»:1:1:
+            1| ++ []
+             | ^
+            2|

tests/functional/lang/parse-fail-unexpected-concat.nix

@@ -0,0 +1 @@
+++ []

tests/functional/lang/parse-fail-unexpected-ellipsis.err.exp

@@ -0,0 +1,5 @@
+error: syntax error, unexpected '...', expecting '.' or '='
+       at «stdin»:1:5:
+            1| { a ... }
+             |     ^
+            2|

tests/functional/lang/parse-fail-unexpected-ellipsis.nix

@@ -0,0 +1 @@
+{ a ... }

tests/functional/lang/parse-fail-unexpected-else.err.exp

@@ -0,0 +1,5 @@
+error: syntax error, unexpected 'else', expecting 'then'
+       at «stdin»:1:6:
+            1| if 1 else
+             |      ^
+            2|

tests/functional/lang/parse-fail-unexpected-else.nix

@@ -0,0 +1 @@
+if 1 else

tests/functional/lang/parse-fail-unexpected-eq.err.exp

@@ -0,0 +1,5 @@
+error: syntax error, unexpected '=='
+       at «stdin»:1:1:
+            1| == 1
+             | ^
+            2|

tests/functional/lang/parse-fail-unexpected-eq.nix

@@ -0,0 +1 @@
+== 1

tests/functional/lang/parse-fail-unexpected-float.err.exp

@@ -0,0 +1,5 @@
+error: syntax error, unexpected floating-point literal, expecting 'inherit'
+       at «stdin»:1:3:
+            1| { 1.5 = x; }
+             |   ^
+            2|

tests/functional/lang/parse-fail-unexpected-float.nix

@@ -0,0 +1 @@
+{ 1.5 = x; }

tests/functional/lang/parse-fail-unexpected-geq.err.exp

@@ -0,0 +1,5 @@
+error: syntax error, unexpected '>='
+       at «stdin»:1:1:
+            1| >= 1
+             | ^
+            2|

tests/functional/lang/parse-fail-unexpected-geq.nix

@@ -0,0 +1 @@
+>= 1

tests/functional/lang/parse-fail-unexpected-hpath.err.exp

@@ -0,0 +1,5 @@
+error: syntax error, unexpected '~/…' path, expecting identifier or 'or' or '${' or '"'
+       at «stdin»:1:3:
+            1| a.~/foo
+             |   ^
+            2|

tests/functional/lang/parse-fail-unexpected-hpath.nix

@@ -0,0 +1 @@
+a.~/foo

tests/functional/lang/parse-fail-unexpected-if.err.exp

@@ -0,0 +1,5 @@
+error: syntax error, unexpected 'if', expecting identifier or 'or' or '${' or '"'
+       at «stdin»:1:3:
+            1| a.if
+             |   ^
+            2|

tests/functional/lang/parse-fail-unexpected-if.nix

@@ -0,0 +1 @@
+a.if

tests/functional/lang/parse-fail-unexpected-impl.err.exp

@@ -0,0 +1,5 @@
+error: syntax error, unexpected '->'
+       at «stdin»:1:1:
+            1| -> x
+             | ^
+            2|

tests/functional/lang/parse-fail-unexpected-impl.nix

@@ -0,0 +1 @@
+-> x

tests/functional/lang/parse-fail-unexpected-in.err.exp

@@ -0,0 +1,5 @@
+error: syntax error, unexpected 'in', expecting identifier or 'or' or '${' or '"'
+       at «stdin»:1:3:
+            1| a.in
+             |   ^
+            2|

tests/functional/lang/parse-fail-unexpected-in.nix

@@ -0,0 +1 @@
+a.in

tests/functional/lang/parse-fail-unexpected-ind-string.err.exp

@@ -0,0 +1,5 @@
+error: syntax error, unexpected start of an indented string, expecting identifier or 'or' or '${' or '"'
+       at «stdin»:1:3:
+            1| a.''
+             |   ^
+            2|

tests/functional/lang/parse-fail-unexpected-ind-string.nix

@@ -0,0 +1 @@
+a.''

tests/functional/lang/parse-fail-unexpected-inherit.err.exp

@@ -0,0 +1,5 @@
+error: syntax error, unexpected 'inherit', expecting identifier or 'or' or '${' or '"'
+       at «stdin»:1:3:
+            1| a.inherit
+             |   ^
+            2|

tests/functional/lang/parse-fail-unexpected-inherit.nix

@@ -0,0 +1 @@
+a.inherit

tests/functional/lang/parse-fail-unexpected-int.err.exp

@@ -0,0 +1,5 @@
+error: syntax error, unexpected integer, expecting 'inherit'
+       at «stdin»:1:3:
+            1| { 1 = x; }
+             |   ^
+            2|

tests/functional/lang/parse-fail-unexpected-int.nix

@@ -0,0 +1 @@
+{ 1 = x; }

tests/functional/lang/parse-fail-unexpected-leq.err.exp

@@ -0,0 +1,5 @@
+error: syntax error, unexpected '<='
+       at «stdin»:1:1:
+            1| <= 1
+             | ^
+            2|

tests/functional/lang/parse-fail-unexpected-leq.nix

@@ -0,0 +1 @@
+<= 1

tests/functional/lang/parse-fail-unexpected-let.err.exp

@@ -0,0 +1,5 @@
+error: syntax error, unexpected 'let', expecting identifier or 'or' or '${' or '"'
+       at «stdin»:1:3:
+            1| a.let
+             |   ^
+            2|

tests/functional/lang/parse-fail-unexpected-let.nix

@@ -0,0 +1 @@
+a.let

tests/functional/lang/parse-fail-unexpected-neq.err.exp

@@ -0,0 +1,5 @@
+error: syntax error, unexpected '!='
+       at «stdin»:1:6:
+            1| 1 != != 2
+             |      ^
+            2|

tests/functional/lang/parse-fail-unexpected-neq.nix

@@ -0,0 +1 @@
+1 != != 2

tests/functional/lang/parse-fail-unexpected-or.err.exp

@@ -0,0 +1,5 @@
+error: syntax error, unexpected '||'
+       at «stdin»:1:1:
+            1| || true
+             | ^
+            2|

tests/functional/lang/parse-fail-unexpected-or.nix

@@ -0,0 +1 @@
+|| true

tests/functional/lang/parse-fail-unexpected-path.err.exp

@@ -0,0 +1,5 @@
+error: syntax error, unexpected path, expecting identifier or 'or' or '${' or '"'
+       at «stdin»:1:7:
+            1| { } ? ./foo
+             |       ^
+            2|

tests/functional/lang/parse-fail-unexpected-path.nix

@@ -0,0 +1 @@
+{ } ? ./foo

tests/functional/lang/parse-fail-unexpected-rec.err.exp

@@ -0,0 +1,5 @@
+error: syntax error, unexpected 'rec', expecting identifier or 'or' or '${' or '"'
+       at «stdin»:1:3:
+            1| a.rec
+             |   ^
+            2|

tests/functional/lang/parse-fail-unexpected-rec.nix

@@ -0,0 +1 @@
+a.rec

tests/functional/lang/parse-fail-unexpected-spath.err.exp

@@ -0,0 +1,5 @@
+error: syntax error, unexpected '<…>' path, expecting identifier or 'or' or '${' or '"'
+       at «stdin»:1:3:
+            1| a.<nixpkgs>
+             |   ^
+            2|

tests/functional/lang/parse-fail-unexpected-spath.nix

@@ -0,0 +1 @@
+a.<nixpkgs>

tests/functional/lang/parse-fail-unexpected-then.err.exp

@@ -0,0 +1,5 @@
+error: syntax error, unexpected 'then'
+       at «stdin»:1:4:
+            1| if then
+             |    ^
+            2|

tests/functional/lang/parse-fail-unexpected-then.nix

@@ -0,0 +1 @@
+if then

tests/functional/lang/parse-fail-unexpected-update.err.exp

@@ -0,0 +1,5 @@
+error: syntax error, unexpected '//'
+       at «stdin»:1:1:
+            1| // 1
+             | ^
+            2|

tests/functional/lang/parse-fail-unexpected-update.nix

@@ -0,0 +1 @@
+// 1

tests/functional/lang/parse-fail-unexpected-uri.err.exp

@@ -0,0 +1,5 @@
+error: syntax error, unexpected URI
+       at «stdin»:1:11:
+            1| { inherit http://x; }
+             |           ^
+            2|

tests/functional/lang/parse-fail-unexpected-uri.nix

@@ -0,0 +1 @@
+{ inherit http://x; }

tests/functional/lang/parse-fail-unexpected-with.err.exp

@@ -0,0 +1,5 @@
+error: syntax error, unexpected 'with', expecting identifier or 'or' or '${' or '"'
+       at «stdin»:1:3:
+            1| a.with
+             |   ^
+            2|

tests/functional/lang/parse-fail-unexpected-with.nix

@@ -0,0 +1 @@
+a.with