gopls/internal/analysis/modernize: fix bug in minmax

Wrong operator. D'oh.

+ test

Fixes golang/go#71721

Change-Id: Ia7fe314df07afa9a9de63c2b6031e678755e9d56
Reviewed-on: https://go-review.googlesource.com/c/tools/+/649357
Reviewed-by: Jonathan Amsterdam <jba@google.com>
Reviewed-by: Alan Donovan <adonovan@google.com>
Auto-Submit: Alan Donovan <adonovan@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

Author: adonovan

gopls/internal/analysis/modernize/minmax.go

@@ -57,7 +57,7 @@ func minmax(pass *analysis.Pass) {
 			if equalSyntax(lhs, lhs2) {
 				if equalSyntax(rhs, a) && equalSyntax(rhs2, b) {
 					sign = +sign
-				} else if equalSyntax(rhs2, a) || equalSyntax(rhs, b) {
+				} else if equalSyntax(rhs2, a) && equalSyntax(rhs, b) {
 					sign = -sign
 				} else {
 					return

gopls/internal/analysis/modernize/testdata/src/minmax/minmax.go

@@ -92,3 +92,14 @@ func nopeAssignHasIncrementOperator() {
 	}
 	print(y)
 }
+
+// Regression test for https://github.com/golang/go/issues/71721.
+func nopeNotAMinimum(x, y int) int {
+	// A value of -1 or 0 will use a default value (30).
+	if x <= 0 {
+		y = 30
+	} else {
+		y = x
+	}
+	return y
+}

gopls/internal/analysis/modernize/testdata/src/minmax/minmax.go.golden

@@ -69,3 +69,14 @@ func nopeAssignHasIncrementOperator() {
 	}
 	print(y)
 }
+
+// Regression test for https://github.com/golang/go/issues/71721.
+func nopeNotAMinimum(x, y int) int {
+	// A value of -1 or 0 will use a default value (30).
+	if x <= 0 {
+		y = 30
+	} else {
+		y = x
+	}
+	return y
+}