Fix-up comment parsing

Author: mgreter

src/interpolation.cpp

@@ -78,11 +78,13 @@ namespace Sass {
       }
     }
 
-    if (auto str = contents.back()->isaItplString()) {
-      text.write(
-        str->text(),
-        str->pstate());
-      contents.pop_back();
+    if (!contents.empty()) {
+      if (auto str = contents.back()->isaItplString()) {
+        text.write(
+          str->text(),
+          str->pstate());
+        contents.pop_back();
+      }
     }
 
   }

src/parser.cpp

@@ -59,7 +59,8 @@ namespace Sass {
     if (scanner.peekChar() != $slash) return false;
     auto next = scanner.peekChar(1);
     if (next == $slash) {
-      lastSilentComment = readSilentComment();
+      //lastSilentComment = read
+      scanSilentComment();
       return true;
     }
     else if (next == $asterisk) {
@@ -72,13 +73,12 @@ namespace Sass {
   }
 
   // Consumes and ignores a silent (Sass-style) comment.
-  SilentComment* Parser::readSilentComment()
+  void Parser::scanSilentComment()
   {
     scanner.expect("//");
     while (!scanner.isDone() && !isNewline(scanner.peekChar())) {
       scanner.readChar();
     }
-    return nullptr;
   }
 
   // Consumes and ignores a loud (CSS-style) comment.

src/parser.hpp

@@ -87,12 +87,11 @@ namespace Sass {
     // Returns whether the comment was consumed.
     bool scanComment();
 
-    // Consumes and ignores a silent (Sass-style) comment.
-    virtual SilentComment* readSilentComment();
-
     // Consumes and ignores a loud (CSS-style) comment.
     virtual void scanLoudComment();
 
+    virtual void scanSilentComment();
+
     // Consumes a plain CSS identifier. If [unit] is `true`, this 
     // doesn't parse a `-` followed by a digit. This ensures that 
     // `1px-2px` parses as subtraction rather than the unit `px-2px`.

src/parser_css.cpp

@@ -53,6 +53,16 @@ namespace Sass {
   }
   // EO readSilentComment
 
+  // Consume a silent comment and throws error
+  void CssParser::scanSilentComment()
+  {
+    Offset start(scanner.offset);
+    lastSilentComment = ScssParser::readSilentComment();
+    error("Silent comments aren't allowed in plain CSS.",
+      scanner.relevantSpanFrom(start));
+  }
+  // EO readSilentComment
+
   // Helper to declare all forbidden at-rules
   bool isForbiddenCssAtRule(const sass::string& name)
   {

src/parser_css.hpp

@@ -41,6 +41,9 @@ namespace Sass {
     // Consume a silent comment and throws error
     SilentComment* readSilentComment() override final;
 
+    // Consume a silent comment and throws error
+    void scanSilentComment() override final;
+
     // Parse allowed at-rule statement and parse children via [child_parser] parser function
     Statement* readAtRule(Statement* (StylesheetParser::* child_parser)(), bool root = false) override final;
 

src/parser_sass.cpp

@@ -16,7 +16,7 @@ namespace Sass {
     Offset start(scanner.offset);
     InterpolationBuffer buffer(scanner);
     do {
-      buffer.addInterpolation(readAlmostAnyValue());
+      buffer.addInterpolation(readAlmostAnyValue(true));
       buffer.writeCharCode($lf);
     } while (buffer.trailingStringEndsWith(",") &&
       scanCharIf(isNewline));

src/parser_sass.hpp

@@ -109,7 +109,7 @@ namespace Sass {
     Statement* parseChild(Statement* (StylesheetParser::* statement)());
 
     // Consumes an indented-style silent comment.
-    SilentComment* readSilentComment() override final;
+    SilentComment* readSilentComment();
 
     // Consumes an indented-style loud context.
     // This overrides loud comment consumption so

src/parser_scss.hpp

@@ -78,7 +78,7 @@ namespace Sass {
       Statement* (StylesheetParser::* statement)()) override;
 
     // Consumes a statement-level silent comment block.
-    virtual SilentComment* readSilentComment() override;
+    virtual SilentComment* readSilentComment();
 
     // Consumes a statement-level loud comment block.
     virtual LoudComment* readLoudComment();

src/parser_stylesheet.cpp

@@ -4576,7 +4576,7 @@ namespace Sass {
   //   the text is expected to be re-parsed.
   // * This supports Sass-style single-line comments.
   // * This does not compress adjacent whitespace characters.
-  Interpolation* StylesheetParser::readAlmostAnyValue()
+  Interpolation* StylesheetParser::readAlmostAnyValue(bool omitComments)
   {
     // const char* start = scanner.position;
     InterpolationBuffer buffer(scanner);
@@ -4606,7 +4606,7 @@ namespace Sass {
       case $slash:
         commentStart = scanner.position;
         if (scanComment()) {
-          buffer.write(scanner.substring(commentStart));
+          if (!omitComments) buffer.write(scanner.substring(commentStart));
         }
         else {
           buffer.write(scanner.readChar());

src/parser_stylesheet.hpp

@@ -460,7 +460,7 @@ namespace Sass {
     //   the text is expected to be re-parsed.
     // * This supports Sass-style single-line comments.
     // * This does not compress adjacent whitespace characters.
-    Interpolation* readAlmostAnyValue();
+    Interpolation* readAlmostAnyValue(bool omitComments = false);
 
     // Consumes tokens until it reaches a top-level `";"`, `")"`, `"]"`, or `"}"` and 
     // returns their contents as a string. If [allowEmpty] is `false` (the default), this