Correctly handle ?-> in encapsed strings

Followup upstream change.

Author: nikic

lib/PhpParser/Lexer/TokenEmulator/NullsafeTokenEmulator.php

@@ -22,15 +22,35 @@ public function emulate(string $code, array $tokens): array
         // the tokens array on the way
         $line = 1;
         for ($i = 0, $c = count($tokens); $i < $c; ++$i) {
-            if (isset($tokens[$i + 1])) {
-                if ($tokens[$i] === '?' && $tokens[$i + 1][0] === \T_OBJECT_OPERATOR) {
-                    array_splice($tokens, $i, 2, [
-                        [\T_NULLSAFE_OBJECT_OPERATOR, '?->', $line]
-                    ]);
-                    $c--;
-                    continue;
+            if ($tokens[$i] === '?' && isset($tokens[$i + 1]) && $tokens[$i + 1][0] === \T_OBJECT_OPERATOR) {
+                array_splice($tokens, $i, 2, [
+                    [\T_NULLSAFE_OBJECT_OPERATOR, '?->', $line]
+                ]);
+                $c--;
+                continue;
+            }
+
+            // Handle ?-> inside encapsed string.
+            if ($tokens[$i][0] === \T_ENCAPSED_AND_WHITESPACE && isset($tokens[$i - 1])
+                && $tokens[$i - 1][0] === \T_VARIABLE
+                && preg_match('/^\?->([a-zA-Z_\x80-\xff][a-zA-Z0-9_\x80-\xff]*)/', $tokens[$i][1], $matches)
+            ) {
+                $replacement = [
+                    [\T_NULLSAFE_OBJECT_OPERATOR, '?->', $line],
+                    [\T_STRING, $matches[1], $line],
+                ];
+                if (\strlen($matches[0]) !== \strlen($tokens[$i][1])) {
+                    $replacement[] = [
+                        \T_ENCAPSED_AND_WHITESPACE,
+                        \substr($tokens[$i][1], \strlen($matches[0])),
+                        $line
+                    ];
                 }
+                array_splice($tokens, $i, 1, $replacement);
+                $c += \count($replacement) - 1;
+                continue;
             }
+
             if (\is_array($tokens[$i])) {
                 $line += substr_count($tokens[$i][1], "\n");
             }

test/PhpParser/Lexer/EmulativeTest.php

@@ -320,6 +320,22 @@ public function provideTestTargetVersion() {
             ['7.4', 'match', [[Tokens::T_STRING, 'match']]],
             ['7.4', 'fn', [[Tokens::T_FN, 'fn']]],
             ['7.3', 'fn', [[Tokens::T_STRING, 'fn']]],
+            // Tested here to skip testLeaveStuffAloneInStrings.
+            ['8.0', '"$foo?->bar"', [
+                [ord('"'), '"'],
+                [Tokens::T_VARIABLE, '$foo'],
+                [Tokens::T_NULLSAFE_OBJECT_OPERATOR, '?->'],
+                [Tokens::T_STRING, 'bar'],
+                [ord('"'), '"'],
+            ]],
+            ['8.0', '"$foo?->bar baz"', [
+                [ord('"'), '"'],
+                [Tokens::T_VARIABLE, '$foo'],
+                [Tokens::T_NULLSAFE_OBJECT_OPERATOR, '?->'],
+                [Tokens::T_STRING, 'bar'],
+                [Tokens::T_ENCAPSED_AND_WHITESPACE, ' baz'],
+                [ord('"'), '"'],
+            ]],
         ];
     }
 }

test/code/parser/expr/nullsafe.test

@@ -71,11 +71,13 @@ array(
     4: Stmt_Expression(
         expr: Scalar_Encapsed(
             parts: array(
-                0: Expr_Variable(
-                    name: a
-                )
-                1: Scalar_EncapsedStringPart(
-                    value: ?->b
+                0: Expr_NullsafePropertyFetch(
+                    var: Expr_Variable(
+                        name: a
+                    )
+                    name: Identifier(
+                        name: b
+                    )
                 )
             )
         )

test/code/prettyPrinter/expr/nullsafe.test

@@ -19,4 +19,4 @@ $a?->b($c)?->d;
 $a?->b($c)();
 new $a?->b();
 "{$a?->b}";
-"{$a}?->b";
+"{$a?->b}";