Multi-line comments should be (#664)

* Add a broken nesting example

* Add some comment examples

* Multi-line comments should be

RE2 `.` does not match newlines by default.  This allows newlines inside multi-line comments.

Author: mjp41

CMakeLists.txt

@@ -11,8 +11,8 @@ set(TRIESTE_BUILD_SAMPLES OFF)
 FetchContent_Declare(
   trieste
   GIT_REPOSITORY https://github.com/microsoft/trieste
-  GIT_TAG fac9e4c84de192ee53051be32c5426256cd1086e
-  GIT_SHALLOW TRUE
+  GIT_TAG 1e1448ca9e4ac158492bf8dbbd86b407c452fc0c
+  GIT_SHALLOW FALSE
 )
 
 FetchContent_MakeAvailable(trieste)

src/parse.cc

@@ -49,6 +49,7 @@ namespace verona
     auto depth = std::make_shared<size_t>(0);
     auto str = std::make_shared<Str>();
     auto indent = std::make_shared<std::vector<size_t>>();
+    auto start_location = std::make_shared<Location>();
     indent->push_back(restart);
 
     p.prefile([](auto&, auto& path) { return path.extension() == ".verona"; });
@@ -202,10 +203,11 @@ namespace verona
 
         // Unescaped string.
         "([']+)\"([^\"]*)" >>
-          [str](auto& m) {
+          [str, start_location](auto& m) {
             str->start = m.match(1).len;
             str->end = 0;
             m.add(String, 2);
+            *start_location = m.match(1);
             m.mode("string");
           },
 
@@ -220,8 +222,10 @@ namespace verona
 
         // Nested comment.
         "/\\*" >>
-          [depth](auto& m) {
+          [depth, start_location](auto& m) {
+            assert(*depth == 0);
             ++(*depth);
+            *start_location = m.match();
             m.mode("comment");
           },
 
@@ -320,6 +324,7 @@ namespace verona
 
     p("comment",
       {
+        "[^/\\*]+" >> [](auto&) {},
         "/\\*" >> [depth](auto&) { ++(*depth); },
 
         "\\*/" >>
@@ -328,12 +333,15 @@ namespace verona
               m.mode("start");
           },
 
-        "." >> [](auto&) {},
+        "[/\\*]" >> [](auto&) {},
       });
 
-    p.done([](auto& m) {
-      if (m.mode() != "start")
-        m.error("unterminated comment at end of file");
+    p.done([start_location](auto& m) {
+      if (m.mode() == "comment")
+        m.error("Unterminated comment starting at ", *start_location);
+
+      if (m.mode() == "string")
+        m.error("Unterminated string starting at ", *start_location);
 
       m.term(terminators);
     });

testsuite/CMakeLists.txt

@@ -91,7 +91,7 @@ foreach(TOOL ${TOOL_FOLDERS})
     # Check if there are any files to compare for this test.
     list(LENGTH results res_length)
     if(res_length EQUAL 0)
-      message(WARNING "Test does not have results directory: ${golden_dir}")
+      message(WARNING "Test does not have results directory: ${golden_dir}\nRun `update-dump` to generate golden files.")
       # Add to generate golden output target
       add_custom_command(OUTPUT ${test_path}
         COMMAND

testsuite/verona_nostdlib/spec/comments.verona

@@ -0,0 +1,38 @@
+// Comment
+
+// Comment /* with nested comment */
+
+// Comment with "quotes"
+
+// Comment with "quotes /* and nested comment */"
+
+// Comment with "quotes /* and nested comment */" and more text
+
+/* Single-line comment */
+/**/
+/* Single-line comment with /*Nested comment*/ */
+
+/* Multi-line
+   comment */
+/*
+
+*/
+/* Multi-line
+   comment /* with nested comment */
+*/
+
+
+// /* Comment opening inside comment ignored
+
+/* // line comment inside comment ignored */
+
+// Interaction with strings:
+let a = "// not a comment!"
+
+let b = "/* not a comment start"
+
+let c = "not a comment end */"
+
+/* Quotes don't affect the nesting. "/*" */ */
+
+// Comment doesn't need a new line to terminate it

testsuite/verona_nostdlib/spec/comments_broken_nest.verona

@@ -0,0 +1 @@
+/* Nested comments /* like this need well bracketed termination */

testsuite/verona_nostdlib/spec/comments_broken_nest_out/00_parse.trieste

@@ -0,0 +1,9 @@
+Verona
+parse
+(top
+  {}
+  (file
+    (group
+      (error
+        (errormsg 33:Unterminated comment starting at )
+        (errorast)))))

testsuite/verona_nostdlib/spec/comments_broken_nest_out/ast

@@ -0,0 +1,9 @@
+Verona
+parse
+(top
+  {}
+  (file
+    (group
+      (error
+        (errormsg 33:Unterminated comment starting at )
+        (errorast)))))

testsuite/verona_nostdlib/spec/comments_broken_nest_out/exit_code.txt

@@ -0,0 +1 @@
+1

testsuite/verona_nostdlib/spec/comments_broken_nest_out/stderr.txt

@@ -0,0 +1,8 @@
+Errors:
+Unterminated comment starting at 
+-- comments_broken_nest.verona:1:1
+/* Nested comments /* like this need well bracketed termination */
+~~
+
+Pass parse failed with 1 error!
+

testsuite/verona_nostdlib/spec/comments_broken_nest_out/stdout.txt

@@ -0,0 +1,23 @@
+Verona
+parse
+(top
+  {}
+  (file
+    (equals
+      (group
+        (let)
+        (ident 1:a))
+      (group
+        (escaped 17:// not a comment!)))
+    (equals
+      (group
+        (let)
+        (ident 1:b))
+      (group
+        (escaped 22:/* not a comment start)))
+    (equals
+      (group
+        (let)
+        (ident 1:c))
+      (group
+        (escaped 20:not a comment end */)))))

testsuite/verona_nostdlib/spec/comments_out/00_parse.trieste

@@ -0,0 +1 @@
+0