Add support for transpiling per-file jsx pragmas

src/compiler/checker.ts

@@ -299,7 +299,7 @@ namespace ts {
             resolveName(name, location, meaning, excludeGlobals) {
                 return resolveName(location, escapeLeadingUnderscores(name), meaning, /*nameNotFoundMessage*/ undefined, /*nameArg*/ undefined, /*isUse*/ false, excludeGlobals);
             },
-            getJsxNamespace: () => unescapeLeadingUnderscores(getJsxNamespace()),
+            getJsxNamespace: n => unescapeLeadingUnderscores(getJsxNamespace(n)),
             getAccessibleSymbolChain,
             getTypePredicateOfSignature,
             resolveExternalModuleSymbol,
@@ -765,7 +765,23 @@ namespace ts {
             }
         }
 
-        function getJsxNamespace(): __String {
+        function getJsxNamespace(location: Node | undefined): __String {
+            if (location) {
+                const file = getSourceFileOfNode(location);
+                if (file) {
+                    if (file.localJsxNamespace) {
+                        return file.localJsxNamespace;
+                    }
+                    const jsxPragma = file.pragmas.get("jsx");
+                    if (jsxPragma) {
+                        const chosenpragma = isArray(jsxPragma) ? jsxPragma[0] : jsxPragma;
+                        file.localJsxFactory = parseIsolatedEntityName(chosenpragma.arguments.factory, languageVersion);
+                        if (file.localJsxFactory) {
+                            return file.localJsxNamespace = getFirstIdentifier(file.localJsxFactory).escapedText;
+                        }
+                    }
+                }
+            }
             if (!_jsxNamespace) {
                 _jsxNamespace = "React" as __String;
                 if (compilerOptions.jsxFactory) {
@@ -15082,8 +15098,10 @@ namespace ts {
         function checkJsxFragment(node: JsxFragment, checkMode: CheckMode): Type {
             checkJsxOpeningLikeElementOrOpeningFragment(node.openingFragment, checkMode);
 
-            if (compilerOptions.jsx === JsxEmit.React && compilerOptions.jsxFactory) {
-                error(node, Diagnostics.JSX_fragment_is_not_supported_when_using_jsxFactory);
+            if (compilerOptions.jsx === JsxEmit.React && (compilerOptions.jsxFactory || getSourceFileOfNode(node).pragmas.has("jsx"))) {
+                error(node, compilerOptions.jsxFactory
+                    ? Diagnostics.JSX_fragment_is_not_supported_when_using_jsxFactory
+                    : Diagnostics.JSX_fragment_is_not_supported_when_using_an_inline_JSX_factory_pragma);
             }
 
             return getJsxGlobalElementType() || anyType;
@@ -15709,7 +15727,7 @@ namespace ts {
             // The reactNamespace/jsxFactory's root symbol should be marked as 'used' so we don't incorrectly elide its import.
             // And if there is no reactNamespace/jsxFactory's symbol in scope when targeting React emit, we should issue an error.
             const reactRefErr = diagnostics && compilerOptions.jsx === JsxEmit.React ? Diagnostics.Cannot_find_name_0 : undefined;
-            const reactNamespace = getJsxNamespace();
+            const reactNamespace = getJsxNamespace(node);
             const reactLocation = isNodeOpeningLikeElement ? (<JsxOpeningLikeElement>node).tagName : node;
             const reactSym = resolveName(reactLocation, reactNamespace, SymbolFlags.Value, reactRefErr, reactNamespace, /*isUse*/ true);
             if (reactSym) {
@@ -25556,7 +25574,7 @@ namespace ts {
                     return !!(symbol && getCheckFlags(symbol) & CheckFlags.Late);
                 },
                 writeLiteralConstValue,
-                getJsxFactoryEntity: () => _jsxFactoryEntity
+                getJsxFactoryEntity: location => location ? (getJsxNamespace(location), (getSourceFileOfNode(location).localJsxFactory || _jsxFactoryEntity)) : _jsxFactoryEntity
             };
 
             // defined here to avoid outer scope pollution

src/compiler/diagnosticMessages.json

@@ -3788,6 +3788,10 @@
         "category": "Error",
         "code": 17016
     },
+    "JSX fragment is not supported when using an inline JSX factory pragma": {
+        "category": "Error",
+        "code": 17017
+    },
 
     "Circularity detected while resolving configuration: {0}": {
         "category": "Error",

src/compiler/factory.ts

@@ -2375,6 +2375,9 @@ namespace ts {
             if (node.resolvedTypeReferenceDirectiveNames !== undefined) updated.resolvedTypeReferenceDirectiveNames = node.resolvedTypeReferenceDirectiveNames;
             if (node.imports !== undefined) updated.imports = node.imports;
             if (node.moduleAugmentations !== undefined) updated.moduleAugmentations = node.moduleAugmentations;
+            if (node.pragmas !== undefined) updated.pragmas = node.pragmas;
+            if (node.localJsxFactory !== undefined) updated.localJsxFactory = node.localJsxFactory;
+            if (node.localJsxNamespace !== undefined) updated.localJsxNamespace = node.localJsxNamespace;
             return updateNode(updated, node);
         }