Restore newline escaping (line continuations) in double-quoted strings

Also make effective escaping in buildspec and command line variable overrides
consistent with double-quoted strings.

3 files changed, 11 insertions, 9 deletions

diff --git a/libbuild2/context.cxx b/libbuild2/context.cxx
index c9f4340..08c4e7e 100644
--- a/libbuild2/context.cxx
+++ b/libbuild2/context.cxx
@@ -378,12 +378,13 @@ namespace build2
       istringstream is (s);
       is.exceptions (istringstream::failbit | istringstream::badbit);
 
-      // Similar to buildspec we do "effective escaping" and only for ['"\$(]
-      // (basically what's necessary inside a double-quoted literal plus the
+      // Similar to buildspec we do "effective escaping" of the special
+      // `'"\$(` characters, line continuations, plus `)` for symmetry
+      // (basically what's escapable inside a double-quoted literal plus the
       // single quote).
       //
       path_name in ("<cmdline>");
-      lexer l (is, in, 1 /* line */, "\'\"\\$(");
+      lexer l (is, in, 1 /* line */, "\'\"\\$()\n");
 
       // At the buildfile level the scope-specific variable should be
       // separated from the directory with a whitespace, for example:
diff --git a/libbuild2/lexer.cxx b/libbuild2/lexer.cxx
index d82c135..04c15be 100644
--- a/libbuild2/lexer.cxx
+++ b/libbuild2/lexer.cxx
@@ -923,10 +923,10 @@ namespace build2
           auto quoted_mode = [this] (lexer_mode m)
           {
             // In the double-quoted mode we only do effective escaping of the
-            // special `$("\` characters plus `)` for symmetry. Nothing can be
-            // escaped in single-quoted.
+            // special `$("\` characters, line continuations, plus `)` for
+            // symmetry. Nothing can be escaped in single-quoted.
             //
-            const char* esc (m == lexer_mode::double_quoted ? "$()\"\\" : "");
+            const char* esc (m == lexer_mode::double_quoted ? "$()\"\\\n" : "");
 
             state_.push (state {
               m, 0, nullopt, false, false, '\0', false, true, true,
diff --git a/libbuild2/parser.cxx b/libbuild2/parser.cxx
index 5128979..4350c88 100644
--- a/libbuild2/parser.cxx
+++ b/libbuild2/parser.cxx
@@ -8163,11 +8163,12 @@ namespace build2
   buildspec parser::
   parse_buildspec (istream& is, const path_name& in)
   {
-    // We do "effective escaping" and only for ['"\$(] (basically what's
-    // necessary inside a double-quoted literal plus the single quote).
+    // We do "effective escaping" of the special `'"\$(` characters, line
+    // continuations, plus `)` for symmetry (basically what's escapable inside
+    // a double-quoted literal plus the single quote).
     //
     path_ = &in;
-    lexer l (is, *path_, 1 /* line */, "\'\"\\$(");
+    lexer l (is, *path_, 1 /* line */, "\'\"\\$()\n");
     lexer_ = &l;
 
     root_ = &ctx->global_scope.rw ();