diff --git a/src/Node/Printer/Printer.php b/src/Node/Printer/Printer.php
index 61ffd313960..af6787dd9e7 100644
--- a/src/Node/Printer/Printer.php
+++ b/src/Node/Printer/Printer.php
@@ -5,6 +5,9 @@
 use Override;
 use PhpParser\Node;
 use PhpParser\Node\Expr;
+use PhpParser\Node\Expr\Cast;
+use PhpParser\Node\Scalar\Int_;
+use PhpParser\Node\Scalar\InterpolatedString;
 use PhpParser\Node\Scalar\String_;
 use PhpParser\PrettyPrinter\Standard;
 use PHPStan\DependencyInjection\AutowiredService;
@@ -31,6 +34,7 @@
 use PHPStan\Node\MethodCallableNode;
 use PHPStan\Node\StaticMethodCallableNode;
 use PHPStan\Type\VerbosityLevel;
+use function in_array;
 use function preg_match;
 use function sprintf;
 use function str_contains;
@@ -103,6 +107,85 @@ protected function pObjectProperty(Node $node): string
 		return parent::pObjectProperty($node);
 	}
 
+	/**
+	 * The `kind` attribute records how a node was spelled in the source, not
+	 * what it means: `'k'`, `"k"` and a nowdoc holding `k` are the same string,
+	 * `1` and `0x1` are the same integer, `array(...)` and `[...]` are the same
+	 * array. Printing it back would make `$a['k']` and `$a["k"]` different
+	 * expression keys, so the analyser would track them as two unrelated
+	 * expressions and narrowing done on one would not apply to the other.
+	 *
+	 * Everything below therefore prints one canonical form per value, chosen
+	 * without looking at `kind`.
+	 */
+	#[Override]
+	protected function pScalar_String(String_ $node): string // phpcs:ignore
+	{
+		// keep escape sequences readable and the printed form single-line
+		if (preg_match('/[\x00-\x1f\x7f]/', $node->value) === 1) {
+			return '"' . $this->escapeString($node->value, '"') . '"';
+		}
+
+		return $this->pSingleQuotedString($node->value);
+	}
+
+	#[Override]
+	protected function pScalar_InterpolatedString(InterpolatedString $node): string // phpcs:ignore
+	{
+		return '"' . $this->pEncapsList($node->parts, '"') . '"';
+	}
+
+	#[Override]
+	protected function pScalar_Int(Int_ $node): string // phpcs:ignore
+	{
+		if ($node->getAttribute('kind', Int_::KIND_DEC) === Int_::KIND_DEC) {
+			return parent::pScalar_Int($node);
+		}
+
+		return parent::pScalar_Int(new Int_($node->value));
+	}
+
+	#[Override]
+	protected function pExpr_Array(Expr\Array_ $node): string // phpcs:ignore
+	{
+		if ($node->getAttribute('kind') === Expr\Array_::KIND_SHORT) {
+			return parent::pExpr_Array($node);
+		}
+
+		return parent::pExpr_Array(new Expr\Array_($node->items, ['kind' => Expr\Array_::KIND_SHORT]));
+	}
+
+	#[Override]
+	protected function pExpr_List(Expr\List_ $node): string // phpcs:ignore
+	{
+		if ($node->getAttribute('kind') === Expr\List_::KIND_ARRAY) {
+			return parent::pExpr_List($node);
+		}
+
+		return parent::pExpr_List(new Expr\List_($node->items, ['kind' => Expr\List_::KIND_ARRAY]));
+	}
+
+	#[Override]
+	protected function pExpr_Cast_Double(Cast\Double $node, int $precedence, int $lhsPrecedence): string // phpcs:ignore
+	{
+		return $this->pPrefixOp(Cast\Double::class, '(float) ', $node->expr, $precedence, $lhsPrecedence);
+	}
+
+	/**
+	 * `true`, `false` and `null` are the only case-insensitive constant names
+	 * in PHP, and `\true` means the same as `true`.
+	 */
+	#[Override]
+	protected function pExpr_ConstFetch(Expr\ConstFetch $node): string // phpcs:ignore
+	{
+		$lowerName = $node->name->toLowerString();
+		if (in_array($lowerName, ['true', 'false', 'null'], true)) {
+			return $lowerName;
+		}
+
+		return parent::pExpr_ConstFetch($node);
+	}
+
 	protected function pPHPStan_Node_TypeExpr(TypeExpr $expr): string // phpcs:ignore
 	{
 		return sprintf('__phpstanType(%s)', $expr->getExprType()->describe(VerbosityLevel::precise()));
diff --git a/tests/PHPStan/Analyser/nsrt/bug-15060.php b/tests/PHPStan/Analyser/nsrt/bug-15060.php
new file mode 100644
index 00000000000..77a859ec185
--- /dev/null
+++ b/tests/PHPStan/Analyser/nsrt/bug-15060.php
@@ -0,0 +1,95 @@
+<?php declare(strict_types = 1);
+
+namespace Bug15060;
+
+use function PHPStan\Testing\assertType;
+
+function search($searchParams): void
+{
+	if (isset($searchParams['test'])) {
+		assertType('mixed~null', $searchParams['test']);
+		if ($searchParams["test"]) {
+			assertType('mixed~(0|0.0|\'\'|\'0\'|array{}|false|null)', $searchParams['test']);
+			assertType('mixed~(0|0.0|\'\'|\'0\'|array{}|false|null)', $searchParams["test"]);
+		}
+
+		if (is_array($searchParams["test"])) {
+			assertType('array<mixed, mixed>', $searchParams['test']);
+			assertType('array<mixed, mixed>', $searchParams["test"]);
+		}
+
+		if (is_array($searchParams["test"]) && $searchParams["test"]) {
+			assertType('non-empty-array<mixed, mixed>', $searchParams['test']);
+			assertType('non-empty-array<mixed, mixed>', $searchParams["test"]);
+		}
+	}
+}
+
+function heredocAndNowdoc($a): void
+{
+	if (is_array($a['test'])) {
+		assertType('array<mixed, mixed>', $a["test"]);
+		assertType('array<mixed, mixed>', $a[<<<'TEST'
+test
+TEST]);
+		assertType('array<mixed, mixed>', $a[<<<TEST
+test
+TEST]);
+	}
+}
+
+function escapeSequences($a): void
+{
+	if (is_array($a["a\nb"])) {
+		assertType('array<mixed, mixed>', $a[<<<TEST
+a
+b
+TEST]);
+	}
+}
+
+function interpolatedString($a, string $s): void
+{
+	if (is_array($a["x$s"])) {
+		assertType('array<mixed, mixed>', $a[<<<TEST
+x$s
+TEST]);
+	}
+}
+
+function integerBases($a): void
+{
+	if (is_array($a[1])) {
+		assertType('array<mixed, mixed>', $a[0x1]);
+		assertType('array<mixed, mixed>', $a[0b1]);
+		assertType('array<mixed, mixed>', $a[01]);
+	}
+}
+
+function arraySyntax($a, string $s): void
+{
+	if (is_array($a[[$s][0]])) {
+		assertType('array<mixed, mixed>', $a[array($s)[0]]);
+	}
+}
+
+function doubleCast($a, float $f): void
+{
+	if (is_array($a[(float) $f])) {
+		assertType('array<mixed, mixed>', $a[(double) $f]);
+	}
+}
+
+function constantCase($a): void
+{
+	if (is_array($a[true])) {
+		assertType('array<mixed, mixed>', $a[TRUE]);
+		assertType('array<mixed, mixed>', $a[\true]);
+	}
+	if (is_array($a[null])) {
+		assertType('array<mixed, mixed>', $a[NULL]);
+	}
+	if (is_array($a[false])) {
+		assertType('array<mixed, mixed>', $a[FALSE]);
+	}
+}
diff --git a/tests/PHPStan/Rules/Arrays/DuplicateKeysInLiteralArraysRuleTest.php b/tests/PHPStan/Rules/Arrays/DuplicateKeysInLiteralArraysRuleTest.php
index 75293922f7f..70effcf0125 100644
--- a/tests/PHPStan/Rules/Arrays/DuplicateKeysInLiteralArraysRuleTest.php
+++ b/tests/PHPStan/Rules/Arrays/DuplicateKeysInLiteralArraysRuleTest.php
@@ -26,7 +26,7 @@ public function testDuplicateKeys(): void
 		define('PHPSTAN_DUPLICATE_KEY', 0);
 		$this->analyse([__DIR__ . '/data/duplicate-keys.php'], [
 			[
-				'Array has 2 duplicate keys with value \'\' (null, NULL).',
+				'Array has 2 duplicate keys with value \'\' (null, null).',
 				15,
 			],
 			[
diff --git a/tests/PHPStan/Rules/Keywords/DeclareStrictTypesRuleTest.php b/tests/PHPStan/Rules/Keywords/DeclareStrictTypesRuleTest.php
index 7aac5f8019e..02aa02d597e 100644
--- a/tests/PHPStan/Rules/Keywords/DeclareStrictTypesRuleTest.php
+++ b/tests/PHPStan/Rules/Keywords/DeclareStrictTypesRuleTest.php
@@ -98,7 +98,7 @@ public function testNonsenseBool(): void
 	{
 		$this->analyse([__DIR__ . '/data/declare-strict-nonsense-bool.php'], [
 			[
-				'Declare strict_types must have 0 or 1 as its value, \true given.',
+				'Declare strict_types must have 0 or 1 as its value, true given.',
 				1,
 			],
 		]);