From cb0d519c33f38b1de356fbbf5e8a0ea2bee029d3 Mon Sep 17 00:00:00 2001
From: mlrprananta <luke.prananta@teampicnic.com>
Date: Fri, 10 Mar 2023 15:33:20 +0100
Subject: [PATCH] Prefer Optional#orElseGet over Optional#orElse for
 non-compile-time input

---
 .../refasterrules/OptionalRules.java           | 18 ++++++++++++++++++
 .../refasterrules/OptionalRulesTestInput.java  |  4 ++++
 .../refasterrules/OptionalRulesTestOutput.java |  5 +++++
 3 files changed, 27 insertions(+)

diff --git a/error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/OptionalRules.java b/error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/OptionalRules.java
index 676c7633e9d..2b5c7ea716c 100644
--- a/error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/OptionalRules.java
+++ b/error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/OptionalRules.java
@@ -3,10 +3,12 @@
 import static com.google.errorprone.refaster.ImportPolicy.STATIC_IMPORT_ALWAYS;
 
 import com.google.common.collect.Streams;
+import com.google.errorprone.matchers.CompileTimeConstantExpressionMatcher;
 import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
 import com.google.errorprone.refaster.annotation.MayOptionallyUse;
+import com.google.errorprone.refaster.annotation.NotMatches;
 import com.google.errorprone.refaster.annotation.Placeholder;
 import com.google.errorprone.refaster.annotation.UseImportPolicy;
 import java.util.Comparator;
@@ -220,6 +222,22 @@ T after(Optional<T> o1, Optional<T> o2) {
     }
   }
 
+  /**
+   * Prefer {@link Optional#orElseGet(Supplier)} over {@link Optional#orElse(Object)} if the given
+   * value is not a compile-time constant.
+   */
+  abstract static class OrElseToOrElseGet<T> {
+    @BeforeTemplate
+    T before(Optional<T> o, @NotMatches(CompileTimeConstantExpressionMatcher.class) T value) {
+      return o.orElse(value);
+    }
+
+    @AfterTemplate
+    T after(Optional<T> o, T value) {
+      return o.orElseGet(() -> value);
+    }
+  }
+
   /**
    * Flatten a stream of {@link Optional}s using {@link Optional#stream()}, rather than using one of
    * the more verbose alternatives.
diff --git a/error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/OptionalRulesTestInput.java b/error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/OptionalRulesTestInput.java
index 5dbe4d699e7..0f0c524fffd 100644
--- a/error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/OptionalRulesTestInput.java
+++ b/error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/OptionalRulesTestInput.java
@@ -119,4 +119,8 @@ ImmutableSet<Optional<String>> testOptionalFilter() {
   Optional<String> testOptionalMap() {
     return Optional.of(1).stream().map(String::valueOf).findAny();
   }
+
+  ImmutableSet<String> testOrElseToOrElseGet() {
+    return ImmutableSet.of(Optional.of("foo").orElse("bar"), Optional.of("foo").orElse(toString()));
+  }
 }
diff --git a/error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/OptionalRulesTestOutput.java b/error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/OptionalRulesTestOutput.java
index e22d20066f7..d40efdc5adb 100644
--- a/error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/OptionalRulesTestOutput.java
+++ b/error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/OptionalRulesTestOutput.java
@@ -112,4 +112,9 @@ ImmutableSet<Optional<String>> testOptionalFilter() {
   Optional<String> testOptionalMap() {
     return Optional.of(1).map(String::valueOf);
   }
+
+  ImmutableSet<String> testOrElseToOrElseGet() {
+    return ImmutableSet.of(
+        Optional.of("foo").orElse("bar"), Optional.of("foo").orElseGet(() -> toString()));
+  }
 }