From ba90986805063d8a4a760cca0eb7752943455b48 Mon Sep 17 00:00:00 2001
From: Sheetal Nandi <shkamat@microsoft.com>
Date: Tue, 30 Mar 2021 11:35:07 -0700
Subject: [PATCH 1/2] Add failing test case

---
 src/testRunner/tsconfig.json                  |  1 +
 src/testRunner/unittests/tsbuild/clean.ts     | 16 ++++++++++++++
 .../file-name-and-output-name-clashing.js     | 21 +++++++++++++++++++
 3 files changed, 38 insertions(+)
 create mode 100644 src/testRunner/unittests/tsbuild/clean.ts
 create mode 100644 tests/baselines/reference/tsbuild/clean/initial-build/file-name-and-output-name-clashing.js

diff --git a/src/testRunner/tsconfig.json b/src/testRunner/tsconfig.json
index 34c55d0d5da99..bf372efb81c20 100644
--- a/src/testRunner/tsconfig.json
+++ b/src/testRunner/tsconfig.json
@@ -113,6 +113,7 @@
         "unittests/services/textChanges.ts",
         "unittests/services/transpile.ts",
         "unittests/tsbuild/amdModulesWithOut.ts",
+        "unittests/tsbuild/clean.ts",
         "unittests/tsbuild/configFileErrors.ts",
         "unittests/tsbuild/configFileExtends.ts",
         "unittests/tsbuild/containerOnlyReferenced.ts",
diff --git a/src/testRunner/unittests/tsbuild/clean.ts b/src/testRunner/unittests/tsbuild/clean.ts
new file mode 100644
index 0000000000000..90bb298529028
--- /dev/null
+++ b/src/testRunner/unittests/tsbuild/clean.ts
@@ -0,0 +1,16 @@
+namespace ts {
+    describe("unittests:: tsbuild - clean", () => {
+        verifyTsc({
+            scenario: "clean",
+            subScenario: `file name and output name clashing`,
+            commandLineArgs: ["--b", "/src/tsconfig.json", "-clean"],
+            fs: () => loadProjectFromFiles({
+                "/src/index.js": "",
+                "/src/bar.ts": "",
+                "/src/tsconfig.json": JSON.stringify({
+                    compilerOptions: { allowJs: true },
+                }),
+            }),
+        });
+    });
+}
\ No newline at end of file
diff --git a/tests/baselines/reference/tsbuild/clean/initial-build/file-name-and-output-name-clashing.js b/tests/baselines/reference/tsbuild/clean/initial-build/file-name-and-output-name-clashing.js
new file mode 100644
index 0000000000000..9bb218a63b5fb
--- /dev/null
+++ b/tests/baselines/reference/tsbuild/clean/initial-build/file-name-and-output-name-clashing.js
@@ -0,0 +1,21 @@
+Input::
+//// [/lib/lib.d.ts]
+
+
+//// [/src/bar.ts]
+
+
+//// [/src/index.js]
+
+
+//// [/src/tsconfig.json]
+{"compilerOptions":{"allowJs":true}}
+
+
+
+Output::
+/lib/tsc --b /src/tsconfig.json -clean
+exitCode:: ExitStatus.Success
+
+
+//// [/src/index.js] unlink

From d728fd32d3b2fec9db4a3a85f5b1bf89fdb0b7e8 Mon Sep 17 00:00:00 2001
From: Sheetal Nandi <shkamat@microsoft.com>
Date: Tue, 30 Mar 2021 15:02:35 -0700
Subject: [PATCH 2/2] Do not delete output file names that are same as input
 file name Fixes #43116

---
 src/compiler/tsbuildPublic.ts                                 | 4 ++++
 .../clean/initial-build/file-name-and-output-name-clashing.js | 1 -
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/compiler/tsbuildPublic.ts b/src/compiler/tsbuildPublic.ts
index ddebecc2e55bd..d642f79a12447 100644
--- a/src/compiler/tsbuildPublic.ts
+++ b/src/compiler/tsbuildPublic.ts
@@ -1717,7 +1717,11 @@ namespace ts {
                 continue;
             }
             const outputs = getAllProjectOutputs(parsed, !host.useCaseSensitiveFileNames());
+            if (!outputs.length) continue;
+            const inputFileNames = new Set(parsed.fileNames.map(f => toPath(state, f)));
             for (const output of outputs) {
+                // If output name is same as input file name, do not delete and ignore the error
+                if (inputFileNames.has(toPath(state, output))) continue;
                 if (host.fileExists(output)) {
                     if (filesToDelete) {
                         filesToDelete.push(output);
diff --git a/tests/baselines/reference/tsbuild/clean/initial-build/file-name-and-output-name-clashing.js b/tests/baselines/reference/tsbuild/clean/initial-build/file-name-and-output-name-clashing.js
index 9bb218a63b5fb..e8cecc75d8cac 100644
--- a/tests/baselines/reference/tsbuild/clean/initial-build/file-name-and-output-name-clashing.js
+++ b/tests/baselines/reference/tsbuild/clean/initial-build/file-name-and-output-name-clashing.js
@@ -18,4 +18,3 @@ Output::
 exitCode:: ExitStatus.Success
 
 
-//// [/src/index.js] unlink