From 1f3c222a06e84682291fa15fe15b7654d4f9c67e Mon Sep 17 00:00:00 2001
From: Earlopain <14981592+Earlopain@users.noreply.github.com>
Date: Mon, 13 Jan 2025 16:31:41 +0100
Subject: [PATCH] Fix parser translator heredoc dedention with leading
 interpolation

```rb
<<~F
  foo
#{}
  bar
F
```

has zero common whitespace.
---
 lib/prism/translation/parser/lexer.rb | 5 +++++
 test/prism/ruby/parser_test.rb        | 1 -
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/lib/prism/translation/parser/lexer.rb b/lib/prism/translation/parser/lexer.rb
index 1808473cad..ace40df5d8 100644
--- a/lib/prism/translation/parser/lexer.rb
+++ b/lib/prism/translation/parser/lexer.rb
@@ -569,6 +569,11 @@ def calculate_heredoc_whitespace(heredoc_token_index)
 
             # String content inside nested heredocs and interpolation is ignored
             if next_token.type == :HEREDOC_START || next_token.type == :EMBEXPR_BEGIN
+              # When interpolation is the first token of a line there is no string
+              # content to check against. There will be no common whitespace.
+              if nesting_level == 0 && next_token.location.start_column == 0
+                result = 0
+              end
               nesting_level += 1
             elsif next_token.type == :HEREDOC_END || next_token.type == :EMBEXPR_END
               nesting_level -= 1
diff --git a/test/prism/ruby/parser_test.rb b/test/prism/ruby/parser_test.rb
index 1542bc6562..7c6b1cbe6a 100644
--- a/test/prism/ruby/parser_test.rb
+++ b/test/prism/ruby/parser_test.rb
@@ -98,7 +98,6 @@ class ParserTest < TestCase
       "heredocs_with_ignored_newlines.txt",
       "methods.txt",
       "strings.txt",
-      "tilde_heredocs.txt",
       "seattlerb/backticks_interpolation_line.txt",
       "seattlerb/bug169.txt",
       "seattlerb/case_in.txt",