fix(vast): 修复 Tokenizer 行号登记与 import/f-string 位置属性与 CPython 不一致

- _ScanStringBody 三引号内引号对 Pos+=1 后未 continue，双重自增
  跳过一个字符，若恰为换行则漏登 _LineStarts 行首，导致其后所有
  行号偏移 -1、字面量 col_offset 超行尾，TPC 引号判断失败将
  单引号单字符误推断为 i8*（1.LOG 编译错误根因）
- alias 节点位置改为名称起始（asname 结束），与 CPython 一致
- f-string 内部表达式绝对偏移补上 FSTRING token 源码起始

lib/vast/ExprParser.py

@@ -991,7 +991,8 @@ class ExprParserMixin(TokenStream):
                 k += 1
             self._FStringExprEnd = k
         # 解析表达式：子 token 流
-        expr_node: N.expr = self._ParseSubExpression(expr_text, outer_tok, expr_start + rel_base)
+        # abs_base = FSTRING token 源码起始 + body 内偏移，映射回源码绝对偏移
+        expr_node: N.expr = self._ParseSubExpression(expr_text, outer_tok, outer_tok.Start + expr_start + rel_base)
         fv: N.FormattedValue = N.FormattedValue(value=expr_node, conversion=conversion, format_spec=format_spec)
         fv.lineno = outer_tok.Line
         fv.col_offset = outer_tok.Col

lib/vast/Parser.py

@@ -315,19 +315,23 @@ class Parser(ExprParserMixin):
         start: Token = self._Next()  # 'import'
         names: list[N.alias] = []
         while True:
-            name_parts: list[str] = []
-            asname: str | None = None
-            # 点分模块名
-            name_parts.append(self._ExpectName().Value)
+            # 点分模块名：alias 位置从首个名称起、到末个名称（或 asname）止
+            name_tok: Token = self._ExpectName()
+            end_tok: Token = name_tok
+            name_parts: list[str] = [name_tok.Value]
             while self._AtOp('.'):
                 self._Next()
-                name_parts.append(self._ExpectName().Value)
+                end_tok = self._ExpectName()
+                name_parts.append(end_tok.Value)
             full: str = '.'.join(name_parts)
+            asname: str | None = None
             if self._AtName('as'):
                 self._Next()
-                asname = self._ExpectName().Value
+                as_tok: Token = self._ExpectName()
+                asname = as_tok.Value
+                end_tok = as_tok
             alias: N.alias = N.alias(name=full, asname=asname)
-            self._FixLoc(alias, start)
+            self._FixLoc(alias, name_tok, end_tok)
             names.append(alias)
             if self._AtOp(','):
                 self._Next()
@@ -359,7 +363,7 @@ class Parser(ExprParserMixin):
             self._SkipNL()
             if not self._AtOp(')'):
                 while True:
-                    names.append(self._ParseImportAlias(start))
+                    names.append(self._ParseImportAlias())
                     self._SkipNL()
                     if self._AtOp(','):
                         self._Next()
@@ -371,13 +375,13 @@ class Parser(ExprParserMixin):
             self._ExpectOp(')')
         else:
             if self._AtOp('*'):
-                self._Next()
+                star_tok: Token = self._Next()
                 alias = N.alias(name='*', asname=None)
-                self._FixLoc(alias, start)
+                self._FixLoc(alias, star_tok)
                 names.append(alias)
             else:
                 while True:
-                    names.append(self._ParseImportAlias(start))
+                    names.append(self._ParseImportAlias())
                     if self._AtOp(','):
                         self._Next()
                         continue
@@ -386,15 +390,22 @@ class Parser(ExprParserMixin):
         self._FixLoc(node, start)
         return node
 
-    def _ParseImportAlias(self, start: Token) -> N.alias:
-        """解析单个 import 别名：name [as alias]。"""
-        name: str = self._ExpectName().Value
+    def _ParseImportAlias(self) -> N.alias:
+        """解析单个 import 别名：name [as alias]。
+
+        alias 节点位置与 CPython 一致：起点为首个名称 token，
+        终点为 asname（存在时）或名称结束 token。
+        """
+        name_tok: Token = self._ExpectName()
         asname: str | None = None
+        end_tok: Token = name_tok
         if self._AtName('as'):
             self._Next()
-            asname = self._ExpectName().Value
-        alias: N.alias = N.alias(name=name, asname=asname)
-        self._FixLoc(alias, start)
+            as_tok: Token = self._ExpectName()
+            asname = as_tok.Value
+            end_tok = as_tok
+        alias: N.alias = N.alias(name=name_tok.Value, asname=asname)
+        self._FixLoc(alias, name_tok, end_tok)
         return alias
 
     def _ParseGlobal(self, kw: str) -> N.AST:

lib/vast/Tokenizer.py

@@ -411,6 +411,7 @@ class Tokenizer:
                         self.Pos += 3
                         return
                     self.Pos += 1
+                    continue
                 else:
                     self.Pos += 1
                     return