From 14bdcbfecd8cfdc284d7d7ccd7e969992999a6f1 Mon Sep 17 00:00:00 2001
From: Kirill Rakhman <kirill.rakhman@jetbrains.com>
Date: Thu, 21 Dec 2023 14:13:03 +0100
Subject: [PATCH] [FIR] Improve NO_ELSE_IN_WHEN message

---
 .../kotlin/fir/analysis/diagnostics/FirDiagnosticRenderers.kt | 4 ++--
 .../fir/analysis/diagnostics/FirErrorsDefaultMessages.kt      | 2 +-
 compiler/testData/cli/jvm/returnAsWhenKey.out                 | 2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirDiagnosticRenderers.kt b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirDiagnosticRenderers.kt
index 6f78fb67be4..d9e3b01a021 100644
--- a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirDiagnosticRenderers.kt
+++ b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirDiagnosticRenderers.kt
@@ -169,11 +169,11 @@ object FirDiagnosticRenderers {
 
     val WHEN_MISSING_CASES = Renderer { missingCases: List<WhenMissingCase> ->
         if (missingCases.singleOrNull() == WhenMissingCase.Unknown) {
-            "'else' branch"
+            "an 'else' branch"
         } else {
             val list = missingCases.joinToString(", ", limit = WHEN_MISSING_LIMIT) { "'$it'" }
             val branches = if (missingCases.size > 1) "branches" else "branch"
-            "$list $branches or 'else' branch instead"
+            "the $list $branches or an 'else' branch"
         }
     }
 
diff --git a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrorsDefaultMessages.kt b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrorsDefaultMessages.kt
index 8fbca8bd847..ad74f32cad5 100644
--- a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrorsDefaultMessages.kt
+++ b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrorsDefaultMessages.kt
@@ -2228,7 +2228,7 @@ object FirErrorsDefaultMessages : BaseDiagnosticRendererFactory() {
 
         // When expressions
         map.put(EXPECTED_CONDITION, "Condition of type 'Boolean' expected.")
-        map.put(NO_ELSE_IN_WHEN, "''when'' expression must be exhaustive. Add the necessary {0}{1}", WHEN_MISSING_CASES, STRING)
+        map.put(NO_ELSE_IN_WHEN, "''when'' expression must be exhaustive. Add {0}{1}.", WHEN_MISSING_CASES, STRING)
         map.put(INVALID_IF_AS_EXPRESSION, "'if' must have both main and 'else' branches when used as an expression.")
         map.put(
             NON_EXHAUSTIVE_WHEN_STATEMENT,
diff --git a/compiler/testData/cli/jvm/returnAsWhenKey.out b/compiler/testData/cli/jvm/returnAsWhenKey.out
index 74881c39cb2..00df6eda40b 100644
--- a/compiler/testData/cli/jvm/returnAsWhenKey.out
+++ b/compiler/testData/cli/jvm/returnAsWhenKey.out
@@ -1,4 +1,4 @@
-compiler/testData/cli/jvm/returnAsWhenKey.kt:4:5: error: 'when' expression must be exhaustive. Add the necessary 'true', 'false' branches or 'else' branch instead
+compiler/testData/cli/jvm/returnAsWhenKey.kt:4:5: error: 'when' expression must be exhaustive. Add the 'true', 'false' branches or an 'else' branch.
     when (true) {
     ^
 COMPILATION_ERROR