libexpr/nix2: Remove CR line endings

Change-Id: Ib4946c9975804e02ea7584e0c7373c82ed4961f9

src/libexpr/parser/grammar2.hh

@@ -15,9 +15,8 @@
 // meant to be language versions or have any other semantic meaning.
 
 // NOTE
-// nix line endings are \n, \r\n, \r. the grammar does not use eol or
-// eolf rules in favor of reproducing the old flex lexer as faithfully as
-// possible, and deferring calculation of positions to downstream users.
+// nix line endings are \n, \r\n, *not* \r. Line endings in strings are
+// normalized to \n.
 
 namespace nix::parser::grammar::v2 {
 
@@ -157,9 +156,17 @@ struct floating : p::seq<
     p::must<p::not_at<_extend_as_path>>
 > {};
 
+// LF or CRLF
+struct eol : p::sor<
+    p8::one<'\n'>,
+    p::seq<p8::one<'\r'>, p::must<p8::one<'\n'>>>
+> {};
+
+// Spacing including comments
 struct sep : p::sor<
-    p::plus<p8::one<' ', '\t', '\r', '\n'>>,
-    p::seq<p8::one<'#'>, p::star<p8::not_one<'\r', '\n'>>>,
+    p::plus<p8::one<' ', '\t', '\n'>>,
+    eol,
+    p::seq<p8::one<'#'>, p::until<eol>>,
     p::seq<p8::string<'/', '*'>, p::until<p8::string<'*', '/'>>>
 > {};
 
@@ -180,7 +187,7 @@ struct expr;
 struct _string {
     template<typename... Inner>
     struct literal : semantic, p::seq<Inner...> {};
-    struct cr_lf : semantic, p::seq<p8::one<'\r'>, p::opt<p8::one<'\n'>>> {};
+    struct cr_lf : semantic, p::seq<p8::one<'\r'>, p::must<p8::one<'\n'>>> {};
     struct interpolation : semantic, p::seq<
         p8::string<'$', '{'>, seps,
         p::must<expr>, seps,

src/libexpr/parser/parser-impl2.inc.cc

@@ -23,6 +23,7 @@ inline constexpr const char * error_message = nullptr;
     template<> inline constexpr auto error_message<__VA_ARGS__>
 
 // These are used everywhere the are wrapped in `must<…>` when parsing fails (instead of the usual backtracking)
+error_message_for(p8::one<'\n'>) = "line endings must be LF or CRLF, found lone \\r";
 error_message_for(p8::one<'{'>) = "expecting '{'";
 error_message_for(p8::one<'}'>) = "expecting '}'";
 error_message_for(p8::one<'"'>) = "expecting '\"'";

src/libutil/experimental-features.cc

@@ -205,6 +205,7 @@ constexpr std::array<ExperimentalFeatureDetails, numXpFeatures> xpFeatureDetails
                 - Interpolation in identifiers needs to always be wrapped in $\{}; `"foo ${bar}"` is not a valid identifier anymore.
             - Removed ancient `let {` syntax. See also the `ancient-let` deprecated feature
             - All Nix code must now be fully valid UTF-8 text.
+            - Line endings must be LF or CLRF, not CR.
         )",
     },
     {

tests/functional/lang/parse-fail-eol-2-2.err.exp

@@ -0,0 +1,6 @@
+error: syntax error, line endings must be LF or CRLF, found lone \r
+       at «stdin»:2:1:
+            1| # foo
+            2| invalid
+             | ^
+            3| # bar

tests/functional/lang/parse-fail-eol-2-2.flags

@@ -0,0 +1 @@
+--extra-experimental-features nix-lang2

tests/functional/lang/parse-fail-eol-2-2.nix

@@ -0,0 +1 @@
+parse-fail-eol-2.nix