From ce490e1c778999d5030599a9984bfea6e1f6d752 Mon Sep 17 00:00:00 2001
From: Sheetal Nandi <shkamat@microsoft.com>
Date: Fri, 15 Mar 2019 15:43:04 -0700
Subject: [PATCH] Check oldest output time with tsconfig time to see if its out
 of date Fixes #26503

---
 src/compiler/tsbuild.ts                    | 11 +++++++++++
 src/testRunner/unittests/tsbuild/sample.ts | 14 ++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/src/compiler/tsbuild.ts b/src/compiler/tsbuild.ts
index c649665cf72..cc27aa2c975 100644
--- a/src/compiler/tsbuild.ts
+++ b/src/compiler/tsbuild.ts
@@ -792,6 +792,17 @@ namespace ts {
                     newerInputFileName: newestInputFileName
                 };
             }
+            else {
+                // Check tsconfig time
+                const tsconfigTime = host.getModifiedTime(project.options.configFilePath!) || missingFileModifiedTime;
+                if (oldestOutputFileTime < tsconfigTime) {
+                    return {
+                        type: UpToDateStatusType.OutOfDateWithSelf,
+                        outOfDateOutputFileName: oldestOutputFileName,
+                        newerInputFileName: project.options.configFilePath!
+                    };
+                }
+            }
 
             if (!buildInfoChecked.hasKey(project.options.configFilePath as ResolvedConfigFileName)) {
                 buildInfoChecked.setValue(project.options.configFilePath as ResolvedConfigFileName, true);
diff --git a/src/testRunner/unittests/tsbuild/sample.ts b/src/testRunner/unittests/tsbuild/sample.ts
index c225840a564..49f9f7aa7e0 100644
--- a/src/testRunner/unittests/tsbuild/sample.ts
+++ b/src/testRunner/unittests/tsbuild/sample.ts
@@ -254,6 +254,20 @@ namespace ts {
                     [Diagnostics.Building_project_0, "/src/tests/tsconfig.json"],
                 );
             });
+
+            it("rebuilds when tsconfig changes", () => {
+                const { fs, host, builder } = initializeWithBuild();
+                replaceText(fs, "/src/tests/tsconfig.json", `"composite": true`, `"composite": true, "target": "es3"`);
+                builder.buildAllProjects();
+                host.assertDiagnosticMessages(
+                    getExpectedDiagnosticForProjectsInBuild("src/core/tsconfig.json", "src/logic/tsconfig.json", "src/tests/tsconfig.json"),
+                    [Diagnostics.Project_0_is_up_to_date_because_newest_input_1_is_older_than_oldest_output_2, "src/core/tsconfig.json", "src/core/anotherModule.ts", "src/core/anotherModule.js"],
+                    [Diagnostics.Project_0_is_up_to_date_because_newest_input_1_is_older_than_oldest_output_2, "src/logic/tsconfig.json", "src/logic/index.ts", "src/logic/index.js"],
+                    [Diagnostics.Project_0_is_out_of_date_because_oldest_output_1_is_older_than_newest_input_2, "src/tests/tsconfig.json", "src/tests/index.js", "src/tests/tsconfig.json"],
+                    [Diagnostics.Building_project_0, "/src/tests/tsconfig.json"],
+                    [Diagnostics.Updating_unchanged_output_timestamps_of_project_0, "/src/tests/tsconfig.json"]
+                );
+            });
         });
 
         describe("downstream-blocked compilations", () => {