keep copies of parser inputs that are in-memory only

the parser modifies its inputs, which means that sharing them between
the error context reporting system and the parser itself can confuse the
reporting system. usually this led to early truncation of error context
reports which, while not dangerous, can be quite confusing.

(cherry picked from commit d384ecd553aa997270b79ee98d02f7cf7e1849e6)
Change-Id: I677646b5675b12b2faa787943646aa36dc6e6ee3

8 files changed, 20 insertions, 7 deletions

diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 1739a04fa..32766950d 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -2745,9 +2745,12 @@ Expr * EvalState::parseExprFromFile(const SourcePath & path, std::shared_ptr<Sta
 
 Expr * EvalState::parseExprFromString(std::string s_, const SourcePath & basePath, std::shared_ptr<StaticEnv> & staticEnv)
 {
-    auto s = make_ref<std::string>(std::move(s_));
-    s->append("\0\0", 2);
-    return parse(s->data(), s->size(), Pos::String{.source = s}, basePath, staticEnv);
+    // NOTE this method (and parseStdin) must take care to *fully copy* their input
+    // into their respective Pos::Origin until the parser stops overwriting its input
+    // data.
+    auto s = make_ref<std::string>(s_);
+    s_.append("\0\0", 2);
+    return parse(s_.data(), s_.size(), Pos::String{.source = s}, basePath, staticEnv);
 }
 
 
@@ -2759,12 +2762,15 @@ Expr * EvalState::parseExprFromString(std::string s, const SourcePath & basePath
 
 Expr * EvalState::parseStdin()
 {
+    // NOTE this method (and parseExprFromString) must take care to *fully copy* their
+    // input into their respective Pos::Origin until the parser stops overwriting its
+    // input data.
     //Activity act(*logger, lvlTalkative, "parsing standard input");
     auto buffer = drainFD(0);
     // drainFD should have left some extra space for terminators
+    auto s = make_ref<std::string>(buffer);
     buffer.append("\0\0", 2);
-    auto s = make_ref<std::string>(std::move(buffer));
-    return parse(s->data(), s->size(), Pos::Stdin{.source = s}, rootPath(CanonPath::fromCwd()), staticBaseEnv);
+    return parse(buffer.data(), buffer.size(), Pos::Stdin{.source = s}, rootPath(CanonPath::fromCwd()), staticBaseEnv);
 }
 
 
diff --git a/tests/functional/lang/parse-fail-dup-attrs-1.err.exp b/tests/functional/lang/parse-fail-dup-attrs-1.err.exp
index 6c3a3510c..ffb5198c1 100644
--- a/tests/functional/lang/parse-fail-dup-attrs-1.err.exp
+++ b/tests/functional/lang/parse-fail-dup-attrs-1.err.exp
@@ -3,3 +3,4 @@ error: attribute 'x' already defined at «stdin»:1:3
             2|   y = 456;
             3|   x = 789;
              |   ^
+            4| }
diff --git a/tests/functional/lang/parse-fail-dup-attrs-2.err.exp b/tests/functional/lang/parse-fail-dup-attrs-2.err.exp
index fecdece20..4607a5d59 100644
--- a/tests/functional/lang/parse-fail-dup-attrs-2.err.exp
+++ b/tests/functional/lang/parse-fail-dup-attrs-2.err.exp
@@ -3,3 +3,4 @@ error: attribute 'x' already defined at «stdin»:9:5
             9|     x = 789;
            10|     inherit (as) x;
              |                 ^
+           11|   };
diff --git a/tests/functional/lang/parse-fail-dup-attrs-3.err.exp b/tests/functional/lang/parse-fail-dup-attrs-3.err.exp
index fecdece20..4607a5d59 100644
--- a/tests/functional/lang/parse-fail-dup-attrs-3.err.exp
+++ b/tests/functional/lang/parse-fail-dup-attrs-3.err.exp
@@ -3,3 +3,4 @@ error: attribute 'x' already defined at «stdin»:9:5
             9|     x = 789;
            10|     inherit (as) x;
              |                 ^
+           11|   };
diff --git a/tests/functional/lang/parse-fail-dup-attrs-4.err.exp b/tests/functional/lang/parse-fail-dup-attrs-4.err.exp
index f85ffea51..c98a8f8d0 100644
--- a/tests/functional/lang/parse-fail-dup-attrs-4.err.exp
+++ b/tests/functional/lang/parse-fail-dup-attrs-4.err.exp
@@ -3,3 +3,4 @@ error: attribute 'services.ssh.port' already defined at «stdin»:2:3
             2|   services.ssh.port = 22;
             3|   services.ssh.port = 23;
              |   ^
+            4| }
diff --git a/tests/functional/lang/parse-fail-dup-attrs-7.err.exp b/tests/functional/lang/parse-fail-dup-attrs-7.err.exp
index 98cea9dae..2daddf380 100644
--- a/tests/functional/lang/parse-fail-dup-attrs-7.err.exp
+++ b/tests/functional/lang/parse-fail-dup-attrs-7.err.exp
@@ -3,3 +3,4 @@ error: attribute 'x' already defined at «stdin»:6:12
             6|     inherit x;
             7|     inherit x;
              |            ^
+            8|   };
diff --git a/tests/functional/lang/parse-fail-undef-var-2.err.exp b/tests/functional/lang/parse-fail-undef-var-2.err.exp
index a58d8dca4..393c454dd 100644
--- a/tests/functional/lang/parse-fail-undef-var-2.err.exp
+++ b/tests/functional/lang/parse-fail-undef-var-2.err.exp
@@ -1,5 +1,6 @@
 error: syntax error, unexpected ':', expecting '}'
        at «stdin»:3:13:
             2|
-            3|   f = {x, y :
+            3|   f = {x, y : ["baz" "bar" z "bat"]}: x + y;
              |             ^
+            4|
diff --git a/tests/functional/lang/parse-fail-utf8.err.exp b/tests/functional/lang/parse-fail-utf8.err.exp
index e83abdb9e..1c83f6eb3 100644
--- a/tests/functional/lang/parse-fail-utf8.err.exp
+++ b/tests/functional/lang/parse-fail-utf8.err.exp
@@ -1,4 +1,5 @@
 error: syntax error, unexpected invalid token, expecting end of file
        at «stdin»:1:5:
-            1| 123 Ã
+            1| 123 é 4
              |     ^
+            2|