Let's see how it did

Author: NullVoxPopuli

packages/core/src/transform/template/template-to-typescript.ts

@@ -355,20 +355,92 @@ export function templateToTypescript(
           node.params.length >= 2,
           () => `{{${formInfo.name}}} requires at least two parameters`,
         );
-
-        mapper.text('(');
-        emitExpression(node.params[0]);
-        mapper.text(') ? (');
-        emitExpression(node.params[1]);
-        mapper.text(') : (');
-
-        if (node.params[2]) {
-          emitExpression(node.params[2]);
+        
+        // Check if this is a conditional modifier case
+        const isModifierHelper = 
+          node.params[1].type === 'SubExpression' && 
+          node.params[1].path.type === 'PathExpression' && 
+          node.params[1].path.original === 'modifier';
+        
+        if (isModifierHelper) {
+          // For conditional modifiers, we need to handle them specially
+          // to avoid type instantiation depth issues
+          mapper.text('(');
+          emitExpression(node.params[0]);
+          mapper.text(') ? (');
+          
+          // For the truthy case, we emit the modifier directly
+          if (node.params[1].type === 'SubExpression') {
+            // Extract the modifier and its arguments
+            const modifierExpr = node.params[1];
+            if (modifierExpr.params.length > 0 && modifierExpr.params[0].type === 'PathExpression') {
+              mapper.text('__glintDSL__.applyModifier(__glintDSL__.resolve(');
+              emitExpression(modifierExpr.params[0]);
+              mapper.text(')(__glintY__.element, ');
+              
+              // Skip the first param (the modifier itself) and emit the rest
+              const restParams = modifierExpr.params.slice(1);
+              for (let [index, param] of restParams.entries()) {
+                if (index > 0) {
+                  mapper.text(', ');
+                }
+                emitExpression(param);
+              }
+              
+              // Handle named args if any
+              if (modifierExpr.hash.pairs.length) {
+                if (restParams.length) {
+                  mapper.text(', ');
+                }
+                
+                mapper.text('{ ');
+                for (let [index, pair] of modifierExpr.hash.pairs.entries()) {
+                  mapper.text(`${pair.key}: `);
+                  emitExpression(pair.value);
+                  
+                  if (index < modifierExpr.hash.pairs.length - 1) {
+                    mapper.text(', ');
+                  }
+                }
+                mapper.text(' }');
+              }
+              
+              mapper.text('))');
+            } else {
+              // Fallback to normal emission if structure is unexpected
+              emitExpression(node.params[1]);
+            }
+          } else {
+            // Fallback to normal emission if structure is unexpected
+            emitExpression(node.params[1]);
+          }
+          
+          mapper.text(') : (');
+          
+          // For the falsy case, emit null or the else branch
+          if (node.params[2]) {
+            emitExpression(node.params[2]);
+          } else {
+            mapper.text('null');
+          }
+          
+          mapper.text(')');
         } else {
-          mapper.text('undefined');
+          // Standard if expression handling (unchanged)
+          mapper.text('(');
+          emitExpression(node.params[0]);
+          mapper.text(') ? (');
+          emitExpression(node.params[1]);
+          mapper.text(') : (');
+          
+          if (node.params[2]) {
+            emitExpression(node.params[2]);
+          } else {
+            mapper.text('undefined');
+          }
+          
+          mapper.text(')');
         }
-
-        mapper.text(')');
       });
     }