From e72e20e025ab14320c79c2dca75721a0a5e002bd Mon Sep 17 00:00:00 2001
From: Eugen Wissner <belka@caraus.de>
Date: Sat, 12 Sep 2026 01:35:30 +0200
Subject: Allow random text after ending the module

---
 boot/lexer.ll                           | 15 ++++++++++++++-
 boot/parser.yy                          |  6 ++++++
 include/elna/boot/driver.h              |  3 +++
 testsuite/compilable/trailing_text.elna |  4 ++++
 4 files changed, 27 insertions(+), 1 deletion(-)
 create mode 100644 testsuite/compilable/trailing_text.elna

diff --git a/boot/lexer.ll b/boot/lexer.ll
index e8dde7c..89eb4ed 100644
--- a/boot/lexer.ll
+++ b/boot/lexer.ll
@@ -55,6 +55,10 @@ EXPONENT [eE][+-]?[[:digit:]]+
 
 %%
 %{
+    if (driver.finished)
+    {
+        return yy::parser::make_YYEOF(this->location);
+    }
     this->location.step();
 %}
 
@@ -65,8 +69,17 @@ EXPONENT [eE][+-]?[[:digit:]]+
     \n+ {
         this->location.step();
     }
+    <<EOF>> {
+        driver.add_error<syntax_error>("Unterminated comment", this->comment_start);
+        BEGIN(INITIAL);
+
+        return yy::parser::make_YYEOF(this->location);
+    }
+}
+\(\* {
+    this->comment_start = this->location;
+    BEGIN(IN_COMMENT);
 }
-\(\* BEGIN(IN_COMMENT);
 [ \t\r] {
     this->location.step();
 }
diff --git a/boot/parser.yy b/boot/parser.yy
index cc0a46c..f97d545 100644
--- a/boot/parser.yy
+++ b/boot/parser.yy
@@ -45,6 +45,8 @@ along with GCC; see the file COPYING3.  If not see
     {
     public:
         yy::location location;
+        /// Where the comment being scanned was opened.
+        yy::location comment_start;
 
         lexer(std::istream& arg_yyin)
             : yyFlexLexer(&arg_yyin)
@@ -167,12 +169,16 @@ along with GCC; see the file COPYING3.  If not see
 program:
     import_part type_part variable_part procedure_part "end" "."
         {
+            driver.finished = true;
+
             boot::unit *tree = new boot::unit(boot::make_position(@$), $1, $2, $3, $4);
 			driver.tree.reset(tree);
         }
     | import_part type_part variable_part procedure_part
             "program" "(" optional_identifiers ")" procedure_body "end" "."
         {
+            driver.finished = true;
+
             boot::unit *tree = new boot::unit(boot::make_position(@$), $1, $2, $3, $4,
                         std::move($7), boot::make_position(@5), std::move(*$9));
 			driver.tree.reset(tree);
diff --git a/include/elna/boot/driver.h b/include/elna/boot/driver.h
index 45e2e40..e918954 100644
--- a/include/elna/boot/driver.h
+++ b/include/elna/boot/driver.h
@@ -39,6 +39,9 @@ namespace elna::boot
     {
     public:
         std::unique_ptr<unit> tree;
+        /// Set once the module terminator has been parsed. The lexer stops
+        /// scanning then, so whatever follows is not program text.
+        bool finished{ false };
 
         driver() = default;
     };
diff --git a/testsuite/compilable/trailing_text.elna b/testsuite/compilable/trailing_text.elna
new file mode 100644
index 0000000..1eb3595
--- /dev/null
+++ b/testsuite/compilable/trailing_text.elna
@@ -0,0 +1,4 @@
+end.
+
+Everything after the module terminator is ignored and is never scanned, so it
+does not have to be Elna: proc 1 2 3 "unterminated
-- 
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