feat: also catch if-else

Author: Madoshakalaka

packages/yew-macro/src/html_tree/html_block.rs

@@ -79,9 +79,40 @@ fn check_deprecated_html_call(expr: &Expr) -> TokenStream {
         }
     }
 
+    // Pattern 3: { if cond { html! { ... } } else { html! { ... } } }
+    if let Expr::If(if_expr) = expr {
+        if let Some(span) = if_branch_html_macro_span(if_expr) {
+            return super::deprecated_call(
+                span,
+                "`html!` is not needed inside `if`/`else` branches. Use bare elements directly",
+            );
+        }
+    }
+
     TokenStream::new()
 }
 
+/// Walk through an `if`/`else if`/`else` chain and return the span of the first tail `html!` call.
+fn if_branch_html_macro_span(if_expr: &syn::ExprIf) -> Option<proc_macro2::Span> {
+    if let Some(span) = if_expr
+        .then_branch
+        .stmts
+        .last()
+        .and_then(stmt_tail_html_macro_span)
+    {
+        return Some(span);
+    }
+    match if_expr.else_branch.as_ref().map(|(_, expr)| expr.as_ref()) {
+        Some(Expr::Block(block_expr)) => block_expr
+            .block
+            .stmts
+            .last()
+            .and_then(stmt_tail_html_macro_span),
+        Some(Expr::If(nested)) => if_branch_html_macro_span(nested),
+        _ => None,
+    }
+}
+
 /// Check if a statement is a tail `html!`/`html_nested!` macro call (no trailing semicolon).
 fn stmt_tail_html_macro_span(stmt: &Stmt) -> Option<proc_macro2::Span> {
     match stmt {

packages/yew-macro/tests/html_deprecation/fail.rs

@@ -81,6 +81,13 @@ fn nested_block_with_html_tail() {
     };
 }
 
+fn if_else_block_with_html_branches() {
+    let cond = true;
+    let _ = html! {
+        <div>{ if cond { html! { <span>{"yes"}</span> } } else { html! { <span>{"no"}</span> } } }</div>
+    };
+}
+
 fn main() {
     compile_error!("This macro call exists to deliberately fail the compilation of the test so we can verify output of deprecation lints");
 }

packages/yew-macro/tests/html_deprecation/fail.stderr

@@ -1,7 +1,7 @@
 error: This macro call exists to deliberately fail the compilation of the test so we can verify output of deprecation lints
-  --> tests/html_deprecation/fail.rs:85:5
+  --> tests/html_deprecation/fail.rs:92:5
    |
-85 |     compile_error!("This macro call exists to deliberately fail the compilation of the test so we can verify output of deprecation lints...
+92 |     compile_error!("This macro call exists to deliberately fail the compilation of the test so we can verify output of deprecation lints...
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 warning: use of deprecated function `root_level_fragment::__yew_deprecated`: unnecessary `<>...</>`. Children can be placed directly in the body
@@ -81,3 +81,9 @@ warning: use of deprecated function `nested_block_with_html_tail::__yew_deprecat
    |
 80 |         <div>{{ let processed = item.to_uppercase(); html! { <span>{processed}</span> } }}</div>
    |                                                      ^^^^
+
+warning: use of deprecated function `if_else_block_with_html_branches::__yew_deprecated`: `html!` is not needed inside `if`/`else` branches. Use bare elements directly
+  --> tests/html_deprecation/fail.rs:87:26
+   |
+87 |         <div>{ if cond { html! { <span>{"yes"}</span> } } else { html! { <span>{"no"}</span> } } }</div>
+   |                          ^^^^