cmListFileLexer: Fix line number after backslash in string

If a line inside a string ends in a backslash count the following
newline character as a line increment.  Add a test covering this case to
verify that subsequent line numbers are correct.

1 files changed, 7 insertions, 1 deletions

diff --git a/Source/cmListFileLexer.in.l b/Source/cmListFileLexer.in.l
index eedf494..4459c7b 100644
--- a/Source/cmListFileLexer.in.l
+++ b/Source/cmListFileLexer.in.l
@@ -125,11 +125,17 @@ MAKEVAR \$\([A-Za-z0-9_]*\)
   BEGIN(STRING);
 }
 
-<STRING>([^\\\n\"]|\\(.|\n))+ {
+<STRING>([^\\\n\"]|\\.)+ {
   cmListFileLexerAppend(lexer, yytext, yyleng);
   lexer->column += yyleng;
 }
 
+<STRING>\\\n {
+  cmListFileLexerAppend(lexer, yytext, yyleng);
+  ++lexer->line;
+  lexer->column = 1;
+}
+
 <STRING>\n {
   cmListFileLexerAppend(lexer, yytext, yyleng);
   ++lexer->line;