From ac4490c0dedd77ee68349ee73d0e0ab8f58091c6 Mon Sep 17 00:00:00 2001
From: Daniel Rosenwasser <Daniel.Rosenwasser@microsoft.com>
Date: Thu, 8 Oct 2020 16:43:00 -0700
Subject: [PATCH 1/8] Add test case for 'useUnknownInCatchVariables'.

---
 .../compiler/useUnknownInCatchVariables01.ts  | 23 +++++++++++++++++++
 1 file changed, 23 insertions(+)
 create mode 100644 tests/cases/compiler/useUnknownInCatchVariables01.ts

diff --git a/tests/cases/compiler/useUnknownInCatchVariables01.ts b/tests/cases/compiler/useUnknownInCatchVariables01.ts
new file mode 100644
index 0000000000000..c9633c97e4fcc
--- /dev/null
+++ b/tests/cases/compiler/useUnknownInCatchVariables01.ts
@@ -0,0 +1,23 @@
+// @useUnknownInCatchVariables: true
+
+try {
+    // ...
+}
+catch (e) {
+    // error!
+    void e.toUpperCase();
+    void e++;
+    void e();
+
+    if (typeof e === "string") {
+        // works!
+        // We've narrowed 'e' down to the type 'string'.
+        console.log(e.toUpperCase());
+    }
+    if (e instanceof Error) {
+        e.stack?.toUpperCase();
+    }
+    if (typeof e === "number") {
+        e++;
+    }
+}
\ No newline at end of file

From 07a9e495e7eaaf3945720d55f9e8a22ea0974e31 Mon Sep 17 00:00:00 2001
From: Daniel Rosenwasser <DanielRosenwasser@users.noreply.github.com>
Date: Wed, 5 May 2021 21:32:11 +0000
Subject: [PATCH 2/8] Add new 'useUnknownInCatchVariables' flag.

---
 src/compiler/checker.ts              | 2 +-
 src/compiler/commandLineParser.ts    | 8 ++++++++
 src/compiler/diagnosticMessages.json | 4 ++++
 src/compiler/types.ts                | 1 +
 4 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 4622e53b001f6..3afe6983c6607 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -8929,7 +8929,7 @@ namespace ts {
             if (isCatchClauseVariableDeclarationOrBindingElement(declaration)) {
                 const typeNode = getEffectiveTypeAnnotationNode(declaration);
                 if (typeNode === undefined) {
-                    return anyType;
+                    return compilerOptions.useUnknownInCatchVariables ? unknownType : anyType;
                 }
                 const type = getTypeOfNode(typeNode);
                 // an errorType will make `checkTryStatement` issue an error
diff --git a/src/compiler/commandLineParser.ts b/src/compiler/commandLineParser.ts
index 253e38a5295b5..819be6fadce94 100644
--- a/src/compiler/commandLineParser.ts
+++ b/src/compiler/commandLineParser.ts
@@ -688,6 +688,14 @@ namespace ts {
             category: Diagnostics.Additional_Checks,
             description: Diagnostics.Require_undeclared_properties_from_index_signatures_to_use_element_accesses
         },
+        {
+            name: "useUnknownInCatchVariables",
+            type: "boolean",
+            affectsSemanticDiagnostics: true,
+            showInSimplifiedHelpView: true,
+            category: Diagnostics.Additional_Checks,
+            description: Diagnostics.Type_catch_clause_variables_as_unknown_instead_of_any,
+        },
 
         // Module Resolution
         {
diff --git a/src/compiler/diagnosticMessages.json b/src/compiler/diagnosticMessages.json
index f4fbe932e93f9..ffa29e0826123 100644
--- a/src/compiler/diagnosticMessages.json
+++ b/src/compiler/diagnosticMessages.json
@@ -5095,6 +5095,10 @@
         "category": "Message",
         "code": 6802
     },
+    "Type catch clause variables as 'unknown' instead of 'any'.": {
+        "category": "Message",
+        "code": 6803
+    },
 
     "Variable '{0}' implicitly has an '{1}' type.": {
         "category": "Error",
diff --git a/src/compiler/types.ts b/src/compiler/types.ts
index f7183d7dd6c27..acb17300e36d1 100644
--- a/src/compiler/types.ts
+++ b/src/compiler/types.ts
@@ -6006,6 +6006,7 @@ namespace ts {
         /* @internal */ suppressOutputPathCheck?: boolean;
         target?: ScriptTarget; // TODO: GH#18217 frequently asserted as defined
         traceResolution?: boolean;
+        useUnknownInCatchVariables?: boolean;
         resolveJsonModule?: boolean;
         types?: string[];
         /** Paths used to compute primary types search locations */

From 4f0baa0ea89c259bee92aaa11a5304a2c2e4c37a Mon Sep 17 00:00:00 2001
From: Daniel Rosenwasser <Daniel.Rosenwasser@microsoft.com>
Date: Thu, 8 Oct 2020 18:07:38 -0700
Subject: [PATCH 3/8] Accepted baselines.

---
 .../reference/api/tsserverlibrary.d.ts        |  1 +
 tests/baselines/reference/api/typescript.d.ts |  1 +
 .../useUnknownInCatchVariables/tsconfig.json  |  5 ++
 .../tsconfig.json                             |  1 +
 .../tsconfig.json                             |  1 +
 .../tsconfig.json                             |  1 +
 .../tsconfig.json                             |  1 +
 .../tsconfig.json                             |  1 +
 .../tsconfig.json                             |  1 +
 .../tsconfig.json                             |  1 +
 .../tsconfig.json                             |  1 +
 .../tsconfig.json                             |  1 +
 .../declarationDir-is-specified.js            |  1 +
 ...-outDir-and-declarationDir-is-specified.js |  1 +
 .../when-outDir-is-specified.js               |  1 +
 .../with-outFile.js                           |  1 +
 ...e-is-specified-with-declaration-enabled.js |  1 +
 .../without-outDir-or-outFile-is-specified.js |  1 +
 .../useUnknownInCatchVariables01.errors.txt   | 35 ++++++++++
 .../reference/useUnknownInCatchVariables01.js | 45 +++++++++++++
 .../useUnknownInCatchVariables01.symbols      | 48 +++++++++++++
 .../useUnknownInCatchVariables01.types        | 67 +++++++++++++++++++
 22 files changed, 217 insertions(+)
 create mode 100644 tests/baselines/reference/showConfig/Shows tsconfig for single option/useUnknownInCatchVariables/tsconfig.json
 create mode 100644 tests/baselines/reference/useUnknownInCatchVariables01.errors.txt
 create mode 100644 tests/baselines/reference/useUnknownInCatchVariables01.js
 create mode 100644 tests/baselines/reference/useUnknownInCatchVariables01.symbols
 create mode 100644 tests/baselines/reference/useUnknownInCatchVariables01.types

diff --git a/tests/baselines/reference/api/tsserverlibrary.d.ts b/tests/baselines/reference/api/tsserverlibrary.d.ts
index e94b1da823f34..7b01b03a8ed39 100644
--- a/tests/baselines/reference/api/tsserverlibrary.d.ts
+++ b/tests/baselines/reference/api/tsserverlibrary.d.ts
@@ -2896,6 +2896,7 @@ declare namespace ts {
         suppressImplicitAnyIndexErrors?: boolean;
         target?: ScriptTarget;
         traceResolution?: boolean;
+        useUnknownInCatchVariables?: boolean;
         resolveJsonModule?: boolean;
         types?: string[];
         /** Paths used to compute primary types search locations */
diff --git a/tests/baselines/reference/api/typescript.d.ts b/tests/baselines/reference/api/typescript.d.ts
index 7b8a24ba088b4..7eb229cd26f21 100644
--- a/tests/baselines/reference/api/typescript.d.ts
+++ b/tests/baselines/reference/api/typescript.d.ts
@@ -2896,6 +2896,7 @@ declare namespace ts {
         suppressImplicitAnyIndexErrors?: boolean;
         target?: ScriptTarget;
         traceResolution?: boolean;
+        useUnknownInCatchVariables?: boolean;
         resolveJsonModule?: boolean;
         types?: string[];
         /** Paths used to compute primary types search locations */
diff --git a/tests/baselines/reference/showConfig/Shows tsconfig for single option/useUnknownInCatchVariables/tsconfig.json b/tests/baselines/reference/showConfig/Shows tsconfig for single option/useUnknownInCatchVariables/tsconfig.json
new file mode 100644
index 0000000000000..19c7c22b6926d
--- /dev/null
+++ b/tests/baselines/reference/showConfig/Shows tsconfig for single option/useUnknownInCatchVariables/tsconfig.json	
@@ -0,0 +1,5 @@
+{
+    "compilerOptions": {
+        "useUnknownInCatchVariables": true
+    }
+}
diff --git a/tests/baselines/reference/tsConfig/Default initialized TSConfig/tsconfig.json b/tests/baselines/reference/tsConfig/Default initialized TSConfig/tsconfig.json
index 194d0d139323d..d6608aca93f1a 100644
--- a/tests/baselines/reference/tsConfig/Default initialized TSConfig/tsconfig.json	
+++ b/tests/baselines/reference/tsConfig/Default initialized TSConfig/tsconfig.json	
@@ -42,6 +42,7 @@
     // "noUncheckedIndexedAccess": true,            /* Include 'undefined' in index signature results */
     // "noImplicitOverride": true,                  /* Ensure overriding members in derived classes are marked with an 'override' modifier. */
     // "noPropertyAccessFromIndexSignature": true,  /* Require undeclared properties from index signatures to use element accesses. */
+    // "useUnknownInCatchVariables": true,          /* Type catch clause variables as 'unknown' instead of 'any'. */
 
     /* Module Resolution Options */
     // "moduleResolution": "node",                  /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
diff --git a/tests/baselines/reference/tsConfig/Initialized TSConfig with advanced options/tsconfig.json b/tests/baselines/reference/tsConfig/Initialized TSConfig with advanced options/tsconfig.json
index 6cd483e76a9f0..3ef4b166551d9 100644
--- a/tests/baselines/reference/tsConfig/Initialized TSConfig with advanced options/tsconfig.json	
+++ b/tests/baselines/reference/tsConfig/Initialized TSConfig with advanced options/tsconfig.json	
@@ -42,6 +42,7 @@
     // "noUncheckedIndexedAccess": true,            /* Include 'undefined' in index signature results */
     // "noImplicitOverride": true,                  /* Ensure overriding members in derived classes are marked with an 'override' modifier. */
     // "noPropertyAccessFromIndexSignature": true,  /* Require undeclared properties from index signatures to use element accesses. */
+    // "useUnknownInCatchVariables": true,          /* Type catch clause variables as 'unknown' instead of 'any'. */
 
     /* Module Resolution Options */
     // "moduleResolution": "node",                  /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
diff --git a/tests/baselines/reference/tsConfig/Initialized TSConfig with boolean value compiler options/tsconfig.json b/tests/baselines/reference/tsConfig/Initialized TSConfig with boolean value compiler options/tsconfig.json
index d10611ebdae17..f04666ebe1bc9 100644
--- a/tests/baselines/reference/tsConfig/Initialized TSConfig with boolean value compiler options/tsconfig.json	
+++ b/tests/baselines/reference/tsConfig/Initialized TSConfig with boolean value compiler options/tsconfig.json	
@@ -42,6 +42,7 @@
     // "noUncheckedIndexedAccess": true,            /* Include 'undefined' in index signature results */
     // "noImplicitOverride": true,                  /* Ensure overriding members in derived classes are marked with an 'override' modifier. */
     // "noPropertyAccessFromIndexSignature": true,  /* Require undeclared properties from index signatures to use element accesses. */
+    // "useUnknownInCatchVariables": true,          /* Type catch clause variables as 'unknown' instead of 'any'. */
 
     /* Module Resolution Options */
     // "moduleResolution": "node",                  /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
diff --git a/tests/baselines/reference/tsConfig/Initialized TSConfig with enum value compiler options/tsconfig.json b/tests/baselines/reference/tsConfig/Initialized TSConfig with enum value compiler options/tsconfig.json
index 485a029ae8329..2e7c979133241 100644
--- a/tests/baselines/reference/tsConfig/Initialized TSConfig with enum value compiler options/tsconfig.json	
+++ b/tests/baselines/reference/tsConfig/Initialized TSConfig with enum value compiler options/tsconfig.json	
@@ -42,6 +42,7 @@
     // "noUncheckedIndexedAccess": true,            /* Include 'undefined' in index signature results */
     // "noImplicitOverride": true,                  /* Ensure overriding members in derived classes are marked with an 'override' modifier. */
     // "noPropertyAccessFromIndexSignature": true,  /* Require undeclared properties from index signatures to use element accesses. */
+    // "useUnknownInCatchVariables": true,          /* Type catch clause variables as 'unknown' instead of 'any'. */
 
     /* Module Resolution Options */
     // "moduleResolution": "node",                  /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
diff --git a/tests/baselines/reference/tsConfig/Initialized TSConfig with files options/tsconfig.json b/tests/baselines/reference/tsConfig/Initialized TSConfig with files options/tsconfig.json
index 66028174a9ea6..3803ca2ff3c4a 100644
--- a/tests/baselines/reference/tsConfig/Initialized TSConfig with files options/tsconfig.json	
+++ b/tests/baselines/reference/tsConfig/Initialized TSConfig with files options/tsconfig.json	
@@ -42,6 +42,7 @@
     // "noUncheckedIndexedAccess": true,            /* Include 'undefined' in index signature results */
     // "noImplicitOverride": true,                  /* Ensure overriding members in derived classes are marked with an 'override' modifier. */
     // "noPropertyAccessFromIndexSignature": true,  /* Require undeclared properties from index signatures to use element accesses. */
+    // "useUnknownInCatchVariables": true,          /* Type catch clause variables as 'unknown' instead of 'any'. */
 
     /* Module Resolution Options */
     // "moduleResolution": "node",                  /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
diff --git a/tests/baselines/reference/tsConfig/Initialized TSConfig with incorrect compiler option value/tsconfig.json b/tests/baselines/reference/tsConfig/Initialized TSConfig with incorrect compiler option value/tsconfig.json
index d926a958770fe..c25bf0ca0cf64 100644
--- a/tests/baselines/reference/tsConfig/Initialized TSConfig with incorrect compiler option value/tsconfig.json	
+++ b/tests/baselines/reference/tsConfig/Initialized TSConfig with incorrect compiler option value/tsconfig.json	
@@ -42,6 +42,7 @@
     // "noUncheckedIndexedAccess": true,            /* Include 'undefined' in index signature results */
     // "noImplicitOverride": true,                  /* Ensure overriding members in derived classes are marked with an 'override' modifier. */
     // "noPropertyAccessFromIndexSignature": true,  /* Require undeclared properties from index signatures to use element accesses. */
+    // "useUnknownInCatchVariables": true,          /* Type catch clause variables as 'unknown' instead of 'any'. */
 
     /* Module Resolution Options */
     // "moduleResolution": "node",                  /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
diff --git a/tests/baselines/reference/tsConfig/Initialized TSConfig with incorrect compiler option/tsconfig.json b/tests/baselines/reference/tsConfig/Initialized TSConfig with incorrect compiler option/tsconfig.json
index 194d0d139323d..d6608aca93f1a 100644
--- a/tests/baselines/reference/tsConfig/Initialized TSConfig with incorrect compiler option/tsconfig.json	
+++ b/tests/baselines/reference/tsConfig/Initialized TSConfig with incorrect compiler option/tsconfig.json	
@@ -42,6 +42,7 @@
     // "noUncheckedIndexedAccess": true,            /* Include 'undefined' in index signature results */
     // "noImplicitOverride": true,                  /* Ensure overriding members in derived classes are marked with an 'override' modifier. */
     // "noPropertyAccessFromIndexSignature": true,  /* Require undeclared properties from index signatures to use element accesses. */
+    // "useUnknownInCatchVariables": true,          /* Type catch clause variables as 'unknown' instead of 'any'. */
 
     /* Module Resolution Options */
     // "moduleResolution": "node",                  /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
diff --git a/tests/baselines/reference/tsConfig/Initialized TSConfig with list compiler options with enum value/tsconfig.json b/tests/baselines/reference/tsConfig/Initialized TSConfig with list compiler options with enum value/tsconfig.json
index 9c4a96d98d35c..4ef16804d93cc 100644
--- a/tests/baselines/reference/tsConfig/Initialized TSConfig with list compiler options with enum value/tsconfig.json	
+++ b/tests/baselines/reference/tsConfig/Initialized TSConfig with list compiler options with enum value/tsconfig.json	
@@ -42,6 +42,7 @@
     // "noUncheckedIndexedAccess": true,            /* Include 'undefined' in index signature results */
     // "noImplicitOverride": true,                  /* Ensure overriding members in derived classes are marked with an 'override' modifier. */
     // "noPropertyAccessFromIndexSignature": true,  /* Require undeclared properties from index signatures to use element accesses. */
+    // "useUnknownInCatchVariables": true,          /* Type catch clause variables as 'unknown' instead of 'any'. */
 
     /* Module Resolution Options */
     // "moduleResolution": "node",                  /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
diff --git a/tests/baselines/reference/tsConfig/Initialized TSConfig with list compiler options/tsconfig.json b/tests/baselines/reference/tsConfig/Initialized TSConfig with list compiler options/tsconfig.json
index dd5852675808c..e87d2b3c1e51a 100644
--- a/tests/baselines/reference/tsConfig/Initialized TSConfig with list compiler options/tsconfig.json	
+++ b/tests/baselines/reference/tsConfig/Initialized TSConfig with list compiler options/tsconfig.json	
@@ -42,6 +42,7 @@
     // "noUncheckedIndexedAccess": true,            /* Include 'undefined' in index signature results */
     // "noImplicitOverride": true,                  /* Ensure overriding members in derived classes are marked with an 'override' modifier. */
     // "noPropertyAccessFromIndexSignature": true,  /* Require undeclared properties from index signatures to use element accesses. */
+    // "useUnknownInCatchVariables": true,          /* Type catch clause variables as 'unknown' instead of 'any'. */
 
     /* Module Resolution Options */
     // "moduleResolution": "node",                  /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
diff --git a/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/declarationDir-is-specified.js b/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/declarationDir-is-specified.js
index 16b925d5936d4..29adfeda75ead 100644
--- a/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/declarationDir-is-specified.js
+++ b/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/declarationDir-is-specified.js
@@ -63,6 +63,7 @@ interface Array<T> { length: number; [n: number]: T; }
     // "noUncheckedIndexedAccess": true,            /* Include 'undefined' in index signature results */
     // "noImplicitOverride": true,                  /* Ensure overriding members in derived classes are marked with an 'override' modifier. */
     // "noPropertyAccessFromIndexSignature": true,  /* Require undeclared properties from index signatures to use element accesses. */
+    // "useUnknownInCatchVariables": true,          /* Type catch clause variables as 'unknown' instead of 'any'. */
 
     /* Module Resolution Options */
     // "moduleResolution": "node",                  /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
diff --git a/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/when-outDir-and-declarationDir-is-specified.js b/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/when-outDir-and-declarationDir-is-specified.js
index 7ce20f4eb951f..e60d85aa9cdd7 100644
--- a/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/when-outDir-and-declarationDir-is-specified.js
+++ b/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/when-outDir-and-declarationDir-is-specified.js
@@ -63,6 +63,7 @@ interface Array<T> { length: number; [n: number]: T; }
     // "noUncheckedIndexedAccess": true,            /* Include 'undefined' in index signature results */
     // "noImplicitOverride": true,                  /* Ensure overriding members in derived classes are marked with an 'override' modifier. */
     // "noPropertyAccessFromIndexSignature": true,  /* Require undeclared properties from index signatures to use element accesses. */
+    // "useUnknownInCatchVariables": true,          /* Type catch clause variables as 'unknown' instead of 'any'. */
 
     /* Module Resolution Options */
     // "moduleResolution": "node",                  /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
diff --git a/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/when-outDir-is-specified.js b/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/when-outDir-is-specified.js
index f35e860335bb8..0b76d527167c5 100644
--- a/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/when-outDir-is-specified.js
+++ b/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/when-outDir-is-specified.js
@@ -63,6 +63,7 @@ interface Array<T> { length: number; [n: number]: T; }
     // "noUncheckedIndexedAccess": true,            /* Include 'undefined' in index signature results */
     // "noImplicitOverride": true,                  /* Ensure overriding members in derived classes are marked with an 'override' modifier. */
     // "noPropertyAccessFromIndexSignature": true,  /* Require undeclared properties from index signatures to use element accesses. */
+    // "useUnknownInCatchVariables": true,          /* Type catch clause variables as 'unknown' instead of 'any'. */
 
     /* Module Resolution Options */
     // "moduleResolution": "node",                  /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
diff --git a/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/with-outFile.js b/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/with-outFile.js
index 8f6c7e53cc61b..88a6158042a45 100644
--- a/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/with-outFile.js
+++ b/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/with-outFile.js
@@ -63,6 +63,7 @@ interface Array<T> { length: number; [n: number]: T; }
     // "noUncheckedIndexedAccess": true,            /* Include 'undefined' in index signature results */
     // "noImplicitOverride": true,                  /* Ensure overriding members in derived classes are marked with an 'override' modifier. */
     // "noPropertyAccessFromIndexSignature": true,  /* Require undeclared properties from index signatures to use element accesses. */
+    // "useUnknownInCatchVariables": true,          /* Type catch clause variables as 'unknown' instead of 'any'. */
 
     /* Module Resolution Options */
     // "moduleResolution": "node",                  /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
diff --git a/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/without-outDir-or-outFile-is-specified-with-declaration-enabled.js b/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/without-outDir-or-outFile-is-specified-with-declaration-enabled.js
index 0bc0a489d1891..5a500b722cecf 100644
--- a/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/without-outDir-or-outFile-is-specified-with-declaration-enabled.js
+++ b/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/without-outDir-or-outFile-is-specified-with-declaration-enabled.js
@@ -63,6 +63,7 @@ interface Array<T> { length: number; [n: number]: T; }
     // "noUncheckedIndexedAccess": true,            /* Include 'undefined' in index signature results */
     // "noImplicitOverride": true,                  /* Ensure overriding members in derived classes are marked with an 'override' modifier. */
     // "noPropertyAccessFromIndexSignature": true,  /* Require undeclared properties from index signatures to use element accesses. */
+    // "useUnknownInCatchVariables": true,          /* Type catch clause variables as 'unknown' instead of 'any'. */
 
     /* Module Resolution Options */
     // "moduleResolution": "node",                  /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
diff --git a/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/without-outDir-or-outFile-is-specified.js b/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/without-outDir-or-outFile-is-specified.js
index 79c6b55b1f1e0..7dda7a0b7d5b4 100644
--- a/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/without-outDir-or-outFile-is-specified.js
+++ b/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/without-outDir-or-outFile-is-specified.js
@@ -63,6 +63,7 @@ interface Array<T> { length: number; [n: number]: T; }
     // "noUncheckedIndexedAccess": true,            /* Include 'undefined' in index signature results */
     // "noImplicitOverride": true,                  /* Ensure overriding members in derived classes are marked with an 'override' modifier. */
     // "noPropertyAccessFromIndexSignature": true,  /* Require undeclared properties from index signatures to use element accesses. */
+    // "useUnknownInCatchVariables": true,          /* Type catch clause variables as 'unknown' instead of 'any'. */
 
     /* Module Resolution Options */
     // "moduleResolution": "node",                  /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
diff --git a/tests/baselines/reference/useUnknownInCatchVariables01.errors.txt b/tests/baselines/reference/useUnknownInCatchVariables01.errors.txt
new file mode 100644
index 0000000000000..21f7d8ba35499
--- /dev/null
+++ b/tests/baselines/reference/useUnknownInCatchVariables01.errors.txt
@@ -0,0 +1,35 @@
+tests/cases/compiler/useUnknownInCatchVariables01.ts(6,12): error TS2339: Property 'toUpperCase' does not exist on type 'unknown'.
+tests/cases/compiler/useUnknownInCatchVariables01.ts(7,10): error TS2356: An arithmetic operand must be of type 'any', 'number', 'bigint' or an enum type.
+tests/cases/compiler/useUnknownInCatchVariables01.ts(8,10): error TS2349: This expression is not callable.
+  Type '{}' has no call signatures.
+
+
+==== tests/cases/compiler/useUnknownInCatchVariables01.ts (3 errors) ====
+    try {
+        // ...
+    }
+    catch (e) {
+        // error!
+        void e.toUpperCase();
+               ~~~~~~~~~~~
+!!! error TS2339: Property 'toUpperCase' does not exist on type 'unknown'.
+        void e++;
+             ~
+!!! error TS2356: An arithmetic operand must be of type 'any', 'number', 'bigint' or an enum type.
+        void e();
+             ~
+!!! error TS2349: This expression is not callable.
+!!! error TS2349:   Type '{}' has no call signatures.
+    
+        if (typeof e === "string") {
+            // works!
+            // We've narrowed 'e' down to the type 'string'.
+            console.log(e.toUpperCase());
+        }
+        if (e instanceof Error) {
+            e.stack?.toUpperCase();
+        }
+        if (typeof e === "number") {
+            e++;
+        }
+    }
\ No newline at end of file
diff --git a/tests/baselines/reference/useUnknownInCatchVariables01.js b/tests/baselines/reference/useUnknownInCatchVariables01.js
new file mode 100644
index 0000000000000..85dc03e4fb033
--- /dev/null
+++ b/tests/baselines/reference/useUnknownInCatchVariables01.js
@@ -0,0 +1,45 @@
+//// [useUnknownInCatchVariables01.ts]
+try {
+    // ...
+}
+catch (e) {
+    // error!
+    void e.toUpperCase();
+    void e++;
+    void e();
+
+    if (typeof e === "string") {
+        // works!
+        // We've narrowed 'e' down to the type 'string'.
+        console.log(e.toUpperCase());
+    }
+    if (e instanceof Error) {
+        e.stack?.toUpperCase();
+    }
+    if (typeof e === "number") {
+        e++;
+    }
+}
+
+//// [useUnknownInCatchVariables01.js]
+var _a;
+try {
+    // ...
+}
+catch (e) {
+    // error!
+    void e.toUpperCase();
+    void e++;
+    void e();
+    if (typeof e === "string") {
+        // works!
+        // We've narrowed 'e' down to the type 'string'.
+        console.log(e.toUpperCase());
+    }
+    if (e instanceof Error) {
+        (_a = e.stack) === null || _a === void 0 ? void 0 : _a.toUpperCase();
+    }
+    if (typeof e === "number") {
+        e++;
+    }
+}
diff --git a/tests/baselines/reference/useUnknownInCatchVariables01.symbols b/tests/baselines/reference/useUnknownInCatchVariables01.symbols
new file mode 100644
index 0000000000000..0511ec3daac7d
--- /dev/null
+++ b/tests/baselines/reference/useUnknownInCatchVariables01.symbols
@@ -0,0 +1,48 @@
+=== tests/cases/compiler/useUnknownInCatchVariables01.ts ===
+try {
+    // ...
+}
+catch (e) {
+>e : Symbol(e, Decl(useUnknownInCatchVariables01.ts, 3, 7))
+
+    // error!
+    void e.toUpperCase();
+>e : Symbol(e, Decl(useUnknownInCatchVariables01.ts, 3, 7))
+
+    void e++;
+>e : Symbol(e, Decl(useUnknownInCatchVariables01.ts, 3, 7))
+
+    void e();
+>e : Symbol(e, Decl(useUnknownInCatchVariables01.ts, 3, 7))
+
+    if (typeof e === "string") {
+>e : Symbol(e, Decl(useUnknownInCatchVariables01.ts, 3, 7))
+
+        // works!
+        // We've narrowed 'e' down to the type 'string'.
+        console.log(e.toUpperCase());
+>console.log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
+>console : Symbol(console, Decl(lib.dom.d.ts, --, --))
+>log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
+>e.toUpperCase : Symbol(String.toUpperCase, Decl(lib.es5.d.ts, --, --))
+>e : Symbol(e, Decl(useUnknownInCatchVariables01.ts, 3, 7))
+>toUpperCase : Symbol(String.toUpperCase, Decl(lib.es5.d.ts, --, --))
+    }
+    if (e instanceof Error) {
+>e : Symbol(e, Decl(useUnknownInCatchVariables01.ts, 3, 7))
+>Error : Symbol(Error, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+
+        e.stack?.toUpperCase();
+>e.stack?.toUpperCase : Symbol(String.toUpperCase, Decl(lib.es5.d.ts, --, --))
+>e.stack : Symbol(Error.stack, Decl(lib.es5.d.ts, --, --))
+>e : Symbol(e, Decl(useUnknownInCatchVariables01.ts, 3, 7))
+>stack : Symbol(Error.stack, Decl(lib.es5.d.ts, --, --))
+>toUpperCase : Symbol(String.toUpperCase, Decl(lib.es5.d.ts, --, --))
+    }
+    if (typeof e === "number") {
+>e : Symbol(e, Decl(useUnknownInCatchVariables01.ts, 3, 7))
+
+        e++;
+>e : Symbol(e, Decl(useUnknownInCatchVariables01.ts, 3, 7))
+    }
+}
diff --git a/tests/baselines/reference/useUnknownInCatchVariables01.types b/tests/baselines/reference/useUnknownInCatchVariables01.types
new file mode 100644
index 0000000000000..f818272aefaa4
--- /dev/null
+++ b/tests/baselines/reference/useUnknownInCatchVariables01.types
@@ -0,0 +1,67 @@
+=== tests/cases/compiler/useUnknownInCatchVariables01.ts ===
+try {
+    // ...
+}
+catch (e) {
+>e : unknown
+
+    // error!
+    void e.toUpperCase();
+>void e.toUpperCase() : undefined
+>e.toUpperCase() : any
+>e.toUpperCase : any
+>e : unknown
+>toUpperCase : any
+
+    void e++;
+>void e++ : undefined
+>e++ : number
+>e : unknown
+
+    void e();
+>void e() : undefined
+>e() : any
+>e : unknown
+
+    if (typeof e === "string") {
+>typeof e === "string" : boolean
+>typeof e : "string" | "number" | "bigint" | "boolean" | "symbol" | "undefined" | "object" | "function"
+>e : unknown
+>"string" : "string"
+
+        // works!
+        // We've narrowed 'e' down to the type 'string'.
+        console.log(e.toUpperCase());
+>console.log(e.toUpperCase()) : void
+>console.log : (...data: any[]) => void
+>console : Console
+>log : (...data: any[]) => void
+>e.toUpperCase() : string
+>e.toUpperCase : () => string
+>e : string
+>toUpperCase : () => string
+    }
+    if (e instanceof Error) {
+>e instanceof Error : boolean
+>e : unknown
+>Error : ErrorConstructor
+
+        e.stack?.toUpperCase();
+>e.stack?.toUpperCase() : string
+>e.stack?.toUpperCase : () => string
+>e.stack : string
+>e : Error
+>stack : string
+>toUpperCase : () => string
+    }
+    if (typeof e === "number") {
+>typeof e === "number" : boolean
+>typeof e : "string" | "number" | "bigint" | "boolean" | "symbol" | "undefined" | "object" | "function"
+>e : unknown
+>"number" : "number"
+
+        e++;
+>e++ : number
+>e : number
+    }
+}

From cc6e761865bdb85dfd4f7d7b3fe6f395205a4af0 Mon Sep 17 00:00:00 2001
From: Daniel Rosenwasser <Daniel.Rosenwasser@microsoft.com>
Date: Wed, 2 Dec 2020 13:16:39 -0800
Subject: [PATCH 4/8] Add test for catch variable explicitly typed as 'any'.

---
 tests/cases/compiler/useUnknownInCatchVariables01.ts | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/tests/cases/compiler/useUnknownInCatchVariables01.ts b/tests/cases/compiler/useUnknownInCatchVariables01.ts
index c9633c97e4fcc..ca9bdda4acbd0 100644
--- a/tests/cases/compiler/useUnknownInCatchVariables01.ts
+++ b/tests/cases/compiler/useUnknownInCatchVariables01.ts
@@ -18,6 +18,18 @@ catch (e) {
         e.stack?.toUpperCase();
     }
     if (typeof e === "number") {
+        e.toExponential();
         e++;
     }
+}
+
+
+try {
+    // ...
+}
+catch (e: any) {
+    // All are allowed.
+    void e.toUpperCase();
+    void e.toExponential();
+    void e();
 }
\ No newline at end of file

From cd08b62641862907acb69a7b3232f173ef64bcb0 Mon Sep 17 00:00:00 2001
From: Daniel Rosenwasser <Daniel.Rosenwasser@microsoft.com>
Date: Wed, 2 Dec 2020 13:18:34 -0800
Subject: [PATCH 5/8] Accepted baselines.

---
 .../useUnknownInCatchVariables01.errors.txt   | 12 +++++++
 .../reference/useUnknownInCatchVariables01.js | 22 ++++++++++++
 .../useUnknownInCatchVariables01.symbols      | 23 +++++++++++++
 .../useUnknownInCatchVariables01.types        | 34 +++++++++++++++++++
 4 files changed, 91 insertions(+)

diff --git a/tests/baselines/reference/useUnknownInCatchVariables01.errors.txt b/tests/baselines/reference/useUnknownInCatchVariables01.errors.txt
index 21f7d8ba35499..017c3ada88cd0 100644
--- a/tests/baselines/reference/useUnknownInCatchVariables01.errors.txt
+++ b/tests/baselines/reference/useUnknownInCatchVariables01.errors.txt
@@ -30,6 +30,18 @@ tests/cases/compiler/useUnknownInCatchVariables01.ts(8,10): error TS2349: This e
             e.stack?.toUpperCase();
         }
         if (typeof e === "number") {
+            e.toExponential();
             e++;
         }
+    }
+    
+    
+    try {
+        // ...
+    }
+    catch (e: any) {
+        // All are allowed.
+        void e.toUpperCase();
+        void e.toExponential();
+        void e();
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/useUnknownInCatchVariables01.js b/tests/baselines/reference/useUnknownInCatchVariables01.js
index 85dc03e4fb033..1e3a867d11855 100644
--- a/tests/baselines/reference/useUnknownInCatchVariables01.js
+++ b/tests/baselines/reference/useUnknownInCatchVariables01.js
@@ -17,8 +17,20 @@ catch (e) {
         e.stack?.toUpperCase();
     }
     if (typeof e === "number") {
+        e.toExponential();
         e++;
     }
+}
+
+
+try {
+    // ...
+}
+catch (e: any) {
+    // All are allowed.
+    void e.toUpperCase();
+    void e.toExponential();
+    void e();
 }
 
 //// [useUnknownInCatchVariables01.js]
@@ -40,6 +52,16 @@ catch (e) {
         (_a = e.stack) === null || _a === void 0 ? void 0 : _a.toUpperCase();
     }
     if (typeof e === "number") {
+        e.toExponential();
         e++;
     }
 }
+try {
+    // ...
+}
+catch (e) {
+    // All are allowed.
+    void e.toUpperCase();
+    void e.toExponential();
+    void e();
+}
diff --git a/tests/baselines/reference/useUnknownInCatchVariables01.symbols b/tests/baselines/reference/useUnknownInCatchVariables01.symbols
index 0511ec3daac7d..f2261f8c36fbf 100644
--- a/tests/baselines/reference/useUnknownInCatchVariables01.symbols
+++ b/tests/baselines/reference/useUnknownInCatchVariables01.symbols
@@ -42,7 +42,30 @@ catch (e) {
     if (typeof e === "number") {
 >e : Symbol(e, Decl(useUnknownInCatchVariables01.ts, 3, 7))
 
+        e.toExponential();
+>e.toExponential : Symbol(Number.toExponential, Decl(lib.es5.d.ts, --, --))
+>e : Symbol(e, Decl(useUnknownInCatchVariables01.ts, 3, 7))
+>toExponential : Symbol(Number.toExponential, Decl(lib.es5.d.ts, --, --))
+
         e++;
 >e : Symbol(e, Decl(useUnknownInCatchVariables01.ts, 3, 7))
     }
 }
+
+
+try {
+    // ...
+}
+catch (e: any) {
+>e : Symbol(e, Decl(useUnknownInCatchVariables01.ts, 27, 7))
+
+    // All are allowed.
+    void e.toUpperCase();
+>e : Symbol(e, Decl(useUnknownInCatchVariables01.ts, 27, 7))
+
+    void e.toExponential();
+>e : Symbol(e, Decl(useUnknownInCatchVariables01.ts, 27, 7))
+
+    void e();
+>e : Symbol(e, Decl(useUnknownInCatchVariables01.ts, 27, 7))
+}
diff --git a/tests/baselines/reference/useUnknownInCatchVariables01.types b/tests/baselines/reference/useUnknownInCatchVariables01.types
index f818272aefaa4..71a25687af0c2 100644
--- a/tests/baselines/reference/useUnknownInCatchVariables01.types
+++ b/tests/baselines/reference/useUnknownInCatchVariables01.types
@@ -60,8 +60,42 @@ catch (e) {
 >e : unknown
 >"number" : "number"
 
+        e.toExponential();
+>e.toExponential() : string
+>e.toExponential : (fractionDigits?: number) => string
+>e : number
+>toExponential : (fractionDigits?: number) => string
+
         e++;
 >e++ : number
 >e : number
     }
 }
+
+
+try {
+    // ...
+}
+catch (e: any) {
+>e : any
+
+    // All are allowed.
+    void e.toUpperCase();
+>void e.toUpperCase() : undefined
+>e.toUpperCase() : any
+>e.toUpperCase : any
+>e : any
+>toUpperCase : any
+
+    void e.toExponential();
+>void e.toExponential() : undefined
+>e.toExponential() : any
+>e.toExponential : any
+>e : any
+>toExponential : any
+
+    void e();
+>void e() : undefined
+>e() : any
+>e : any
+}

From f5294570c8e1f71c678055cb90c2e2b97c562d6c Mon Sep 17 00:00:00 2001
From: Daniel Rosenwasser <DanielRosenwasser@users.noreply.github.com>
Date: Wed, 5 May 2021 21:35:57 +0000
Subject: [PATCH 6/8] Move option under 'strict'.

---
 src/compiler/checker.ts   | 3 ++-
 src/compiler/utilities.ts | 1 +
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 3afe6983c6607..b098c42b53446 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -354,6 +354,7 @@ namespace ts {
         const strictPropertyInitialization = getStrictOptionValue(compilerOptions, "strictPropertyInitialization");
         const noImplicitAny = getStrictOptionValue(compilerOptions, "noImplicitAny");
         const noImplicitThis = getStrictOptionValue(compilerOptions, "noImplicitThis");
+        const useUnknownInCatchVariables = getStrictOptionValue(compilerOptions, "useUnknownInCatchVariables");
         const keyofStringsOnly = !!compilerOptions.keyofStringsOnly;
         const freshObjectLiteralFlag = compilerOptions.suppressExcessPropertyErrors ? 0 : ObjectFlags.FreshLiteral;
 
@@ -8929,7 +8930,7 @@ namespace ts {
             if (isCatchClauseVariableDeclarationOrBindingElement(declaration)) {
                 const typeNode = getEffectiveTypeAnnotationNode(declaration);
                 if (typeNode === undefined) {
-                    return compilerOptions.useUnknownInCatchVariables ? unknownType : anyType;
+                    return useUnknownInCatchVariables ? unknownType : anyType;
                 }
                 const type = getTypeOfNode(typeNode);
                 // an errorType will make `checkTryStatement` issue an error
diff --git a/src/compiler/utilities.ts b/src/compiler/utilities.ts
index 9bbdea8a6ac2d..88ba75d138247 100644
--- a/src/compiler/utilities.ts
+++ b/src/compiler/utilities.ts
@@ -6067,6 +6067,7 @@ namespace ts {
         | "strictBindCallApply"
         | "strictPropertyInitialization"
         | "alwaysStrict"
+        | "useUnknownInCatchVariables"
         ;
 
     export function getStrictOptionValue(compilerOptions: CompilerOptions, flag: StrictOptionName): boolean {

From a32013b7ef4715f426dac74ca89eb6bfcf7c8335 Mon Sep 17 00:00:00 2001
From: Daniel Rosenwasser <DanielRosenwasser@users.noreply.github.com>
Date: Wed, 5 May 2021 22:13:48 +0000
Subject: [PATCH 7/8] Accepted baselines.

---
 .../controlFlowForCatchAndFinally.types       |  2 +-
 .../tryCatchFinallyControlFlow.types          | 30 +++++++++----------
 ...tatus.DiagnosticsPresent_OutputsSkipped.js |  1 +
 .../reference/typedefOnStatements.types       |  2 +-
 4 files changed, 18 insertions(+), 17 deletions(-)

diff --git a/tests/baselines/reference/controlFlowForCatchAndFinally.types b/tests/baselines/reference/controlFlowForCatchAndFinally.types
index a041cac8ce09a..c159655a0a816 100644
--- a/tests/baselines/reference/controlFlowForCatchAndFinally.types
+++ b/tests/baselines/reference/controlFlowForCatchAndFinally.types
@@ -120,7 +120,7 @@ class Foo {
 >Aborter : typeof Aborter
 
         } catch (error) {
->error : any
+>error : unknown
 
             if (this.abortController !== undefined) {
 >this.abortController !== undefined : boolean
diff --git a/tests/baselines/reference/tryCatchFinallyControlFlow.types b/tests/baselines/reference/tryCatchFinallyControlFlow.types
index 1674907b3a266..b5fb0cf95cc8c 100644
--- a/tests/baselines/reference/tryCatchFinallyControlFlow.types
+++ b/tests/baselines/reference/tryCatchFinallyControlFlow.types
@@ -19,10 +19,10 @@ function f1() {
 >a : number
     }
     catch (e) {
->e : any
+>e : unknown
 
         throw e;
->e : any
+>e : unknown
     }
     finally {
         if (a != null && a.toFixed(0) == "123") { 
@@ -55,7 +55,7 @@ function f2() {
 >1 : 1
     }
     catch (e) {
->e : any
+>e : unknown
 
         x = 2;
 >x = 2 : 2
@@ -63,7 +63,7 @@ function f2() {
 >2 : 2
 
         throw e;
->e : any
+>e : unknown
     }
     finally {
         x;  // 0 | 1 | 2
@@ -87,7 +87,7 @@ function f3() {
 >1 : 1
     }
     catch (e) {
->e : any
+>e : unknown
 
         x = 2;
 >x = 2 : 2
@@ -118,7 +118,7 @@ function f4() {
 >1 : 1
     }
     catch (e) {
->e : any
+>e : unknown
 
         x = 2;
 >x = 2 : 2
@@ -149,7 +149,7 @@ function f5() {
         return;
     }
     catch (e) {
->e : any
+>e : unknown
 
         x = 2;
 >x = 2 : 2
@@ -178,7 +178,7 @@ function f6() {
 >1 : 1
     }
     catch (e) {
->e : any
+>e : unknown
 
         x = 2;
 >x = 2 : 2
@@ -211,7 +211,7 @@ function f7() {
         return;
     }
     catch (e) {
->e : any
+>e : unknown
 
         x = 2;
 >x = 2 : 2
@@ -324,7 +324,7 @@ function f10() {
             return;
         }
         catch (e) {
->e : any
+>e : unknown
 
             x = 2;
 >x = 2 : 2
@@ -388,7 +388,7 @@ function f11() {
             }
         }
         catch (e) {
->e : any
+>e : unknown
 
             x;  // 0 | 1 | 2
 >x : 0 | 1 | 2
@@ -466,7 +466,7 @@ function f12() {
             }
         }
         catch (e) {
->e : any
+>e : unknown
 
             x;  // 0 | 1 | 2
 >x : 0 | 1 | 2
@@ -576,7 +576,7 @@ function t1() {
 >'x' : "x"
         }
         catch (e) {
->e : any
+>e : unknown
 
             return null;
 >null : null
@@ -626,7 +626,7 @@ function notallowed(arg: number) {
         finally { }
     }
     catch (err) {
->err : any
+>err : unknown
 
         state.tag;
 >state.tag : "one" | "two" | "three"
@@ -770,7 +770,7 @@ function f21() {
 >x : 3 | 4 | 5
     }
     catch (e) {
->e : any
+>e : unknown
 
         x;  // 0 | 1 | 2 | 3 | 4 | 5
 >x : 0 | 1 | 2 | 3 | 4 | 5
diff --git a/tests/baselines/reference/tsc/runWithoutArgs/initial-build/show-help-with-ExitStatus.DiagnosticsPresent_OutputsSkipped.js b/tests/baselines/reference/tsc/runWithoutArgs/initial-build/show-help-with-ExitStatus.DiagnosticsPresent_OutputsSkipped.js
index 362d9209ea89e..774fd29297a9b 100644
--- a/tests/baselines/reference/tsc/runWithoutArgs/initial-build/show-help-with-ExitStatus.DiagnosticsPresent_OutputsSkipped.js
+++ b/tests/baselines/reference/tsc/runWithoutArgs/initial-build/show-help-with-ExitStatus.DiagnosticsPresent_OutputsSkipped.js
@@ -48,6 +48,7 @@ Options:
  --noUnusedParameters                               Report errors on unused parameters.
  --noImplicitReturns                                Report error when not all code paths in function return a value.
  --noFallthroughCasesInSwitch                       Report errors for fallthrough cases in switch statement.
+ --useUnknownInCatchVariables                       Type catch clause variables as 'unknown' instead of 'any'.
  --types                                            Type declaration files to be included in compilation.
  --esModuleInterop                                  Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'.
  @<file>                                            Insert command line options and files from a file.
diff --git a/tests/baselines/reference/typedefOnStatements.types b/tests/baselines/reference/typedefOnStatements.types
index 007a6a41d7658..c30a83a8afa81 100644
--- a/tests/baselines/reference/typedefOnStatements.types
+++ b/tests/baselines/reference/typedefOnStatements.types
@@ -68,7 +68,7 @@ throw new Error('Unreachable')
 try {
 }
 catch (e) {
->e : any
+>e : unknown
 }
 
 /**

From 0ea20ffb3a06dd1b270b0ceec11a54a18980fff1 Mon Sep 17 00:00:00 2001
From: Daniel Rosenwasser <DanielRosenwasser@users.noreply.github.com>
Date: Wed, 19 May 2021 07:47:33 +0000
Subject: [PATCH 8/8] 'useUnknownInCatchVariables' is strict in command line
 help.

---
 src/compiler/commandLineParser.ts | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/compiler/commandLineParser.ts b/src/compiler/commandLineParser.ts
index 819be6fadce94..390d3cb800ea8 100644
--- a/src/compiler/commandLineParser.ts
+++ b/src/compiler/commandLineParser.ts
@@ -692,6 +692,7 @@ namespace ts {
             name: "useUnknownInCatchVariables",
             type: "boolean",
             affectsSemanticDiagnostics: true,
+            strictFlag: true,
             showInSimplifiedHelpView: true,
             category: Diagnostics.Additional_Checks,
             description: Diagnostics.Type_catch_clause_variables_as_unknown_instead_of_any,