fix(heredoc): handle unbalanced single quotes and backticks in heredoc bodies inside $(…) (#420)

brush-parser/src/snapshots/brush_parser__word__tests__parse_command_sub_with_balanced_backticks.snap

@@ -0,0 +1,20 @@
+---
+source: brush-parser/src/word.rs
+expression: "test_parse(\"\\\"$(cat <<'EOF'\\n`hello`\\nEOF\\n)\\\"\")?"
+---
+ParseTestResults(
+  input: "\"$(cat <<\'EOF\'\n`hello`\nEOF\n)\"",
+  result: [
+    WordPieceWithSource(
+      piece: DoubleQuotedSequence([
+        WordPieceWithSource(
+          piece: CommandSubstitution("cat <<\'EOF\'\n`hello`\nEOF\n"),
+          start_index: 1,
+          end_index: 28,
+        ),
+      ]),
+      start_index: 0,
+      end_index: 29,
+    ),
+  ],
+)

brush-parser/src/snapshots/brush_parser__word__tests__parse_command_sub_with_balanced_double_quotes.snap

@@ -0,0 +1,20 @@
+---
+source: brush-parser/src/word.rs
+expression: "test_parse(\"\\\"$(cat <<'EOF'\\n\\\"hello\\\"\\nEOF\\n)\\\"\")?"
+---
+ParseTestResults(
+  input: "\"$(cat <<\'EOF\'\n\"hello\"\nEOF\n)\"",
+  result: [
+    WordPieceWithSource(
+      piece: DoubleQuotedSequence([
+        WordPieceWithSource(
+          piece: CommandSubstitution("cat <<\'EOF\'\n\"hello\"\nEOF\n"),
+          start_index: 1,
+          end_index: 28,
+        ),
+      ]),
+      start_index: 0,
+      end_index: 29,
+    ),
+  ],
+)

brush-parser/src/snapshots/brush_parser__word__tests__parse_command_sub_with_balanced_single_quotes.snap

@@ -0,0 +1,20 @@
+---
+source: brush-parser/src/word.rs
+expression: "test_parse(\"\\\"$(cat <<'EOF'\\n'hello'\\nEOF\\n)\\\"\")?"
+---
+ParseTestResults(
+  input: "\"$(cat <<\'EOF\'\n\'hello\'\nEOF\n)\"",
+  result: [
+    WordPieceWithSource(
+      piece: DoubleQuotedSequence([
+        WordPieceWithSource(
+          piece: CommandSubstitution("cat <<\'EOF\'\n\'hello\'\nEOF\n"),
+          start_index: 1,
+          end_index: 28,
+        ),
+      ]),
+      start_index: 0,
+      end_index: 29,
+    ),
+  ],
+)

brush-parser/src/snapshots/brush_parser__word__tests__parse_command_sub_with_unbalanced_backtick.snap

@@ -0,0 +1,20 @@
+---
+source: brush-parser/src/word.rs
+expression: "test_parse(\"\\\"$(cat <<'EOF'\\na ` b\\nEOF\\n)\\\"\")?"
+---
+ParseTestResults(
+  input: "\"$(cat <<\'EOF\'\na ` b\nEOF\n)\"",
+  result: [
+    WordPieceWithSource(
+      piece: DoubleQuotedSequence([
+        WordPieceWithSource(
+          piece: CommandSubstitution("cat <<\'EOF\'\na ` b\nEOF\n"),
+          start_index: 1,
+          end_index: 26,
+        ),
+      ]),
+      start_index: 0,
+      end_index: 27,
+    ),
+  ],
+)

brush-parser/src/snapshots/brush_parser__word__tests__parse_command_sub_with_unbalanced_single_quote.snap

@@ -0,0 +1,20 @@
+---
+source: brush-parser/src/word.rs
+expression: "test_parse(\"\\\"$(cat <<'EOF'\\nit's here\\nEOF\\n)\\\"\")?"
+---
+ParseTestResults(
+  input: "\"$(cat <<\'EOF\'\nit\'s here\nEOF\n)\"",
+  result: [
+    WordPieceWithSource(
+      piece: DoubleQuotedSequence([
+        WordPieceWithSource(
+          piece: CommandSubstitution("cat <<\'EOF\'\nit\'s here\nEOF\n"),
+          start_index: 1,
+          end_index: 30,
+        ),
+      ]),
+      start_index: 0,
+      end_index: 31,
+    ),
+  ],
+)

brush-parser/src/word.rs

@@ -1075,7 +1075,8 @@ peg::parser! {
 
         pub(crate) rule command_piece() -> () =
             word_piece(<[')']>, true /*in_command*/) {} /
-            ([' ' | '\t'])+ {}
+            ([' ' | '\t'])+ {} /
+            ['\'' | '`'] {}
 
         rule backquoted_command() -> String =
             chars:(backquoted_char()*) { chars.into_iter().collect() }
@@ -1263,6 +1264,36 @@ mod tests {
         Ok(())
     }
 
+    #[test]
+    fn parse_command_sub_with_unbalanced_single_quote() -> Result<()> {
+        assert_ron_snapshot!(test_parse("\"$(cat <<'EOF'\nit's here\nEOF\n)\"")?);
+        Ok(())
+    }
+
+    #[test]
+    fn parse_command_sub_with_unbalanced_backtick() -> Result<()> {
+        assert_ron_snapshot!(test_parse("\"$(cat <<'EOF'\na ` b\nEOF\n)\"")?);
+        Ok(())
+    }
+
+    #[test]
+    fn parse_command_sub_with_balanced_double_quotes() -> Result<()> {
+        assert_ron_snapshot!(test_parse("\"$(cat <<'EOF'\n\"hello\"\nEOF\n)\"")?);
+        Ok(())
+    }
+
+    #[test]
+    fn parse_command_sub_with_balanced_single_quotes() -> Result<()> {
+        assert_ron_snapshot!(test_parse("\"$(cat <<'EOF'\n'hello'\nEOF\n)\"")?);
+        Ok(())
+    }
+
+    #[test]
+    fn parse_command_sub_with_balanced_backticks() -> Result<()> {
+        assert_ron_snapshot!(test_parse("\"$(cat <<'EOF'\n`hello`\nEOF\n)\"")?);
+        Ok(())
+    }
+
     #[test]
     fn parse_backquoted_command() -> Result<()> {
         assert_ron_snapshot!(test_parse("`echo hi`")?);

brush-shell/tests/cases/compat/here.yaml

@@ -250,3 +250,34 @@ cases:
       true
       EOF
       )
+
+  - name: "Here doc with unpaired single quote in command substitution"
+    stdin: |
+      echo "$(cat <<'EOF'
+      it's here
+      EOF
+      )"
+
+  - name: "Here doc with unpaired backtick in command substitution"
+    stdin: |
+      echo "$(cat <<'EOF'
+      a ` b
+      EOF
+      )"
+
+  - name: "Here doc with three single quotes in command substitution"
+    stdin: |
+      echo "$(cat <<'EOF'
+      it's Bob's it's
+      EOF
+      )"
+
+  - name: "Here doc with unpaired single quote in command substitution (#420)"
+    stdin: |
+      var=$(
+        sed 's/nice/cool/' - <<-EOF
+        that's
+        "nice"
+      EOF
+      )
+      echo $var