derive: fail if requested template block is missing

rinja_derive/src/generator.rs

@@ -27,7 +27,7 @@ pub(crate) fn template_to_string(
     heritage: Option<&Heritage<'_, '_>>,
     tmpl_kind: TmplKind<'_>,
 ) -> Result<usize, CompileError> {
-    let generator = Generator::new(
+    let mut generator = Generator::new(
         input,
         contexts,
         heritage,
@@ -36,13 +36,24 @@ pub(crate) fn template_to_string(
         0,
     );
     let size_hint = match generator.impl_template(buf, tmpl_kind) {
-        Err(mut err) if err.span.is_none() => {
-            err.span = input.source_span;
-            Err(err)
+        Ok(size_hint) => {
+            if !generator.block_encountered {
+                if let Some((block, span)) = generator.input.block {
+                    return Err(CompileError::no_file_info(
+                        format_args!("block `{block}` was not contained in the template"),
+                        Some(span),
+                    ));
+                }
+            }
+            size_hint
         }
-        result => result,
-    }?;
-
+        Err(mut err) => {
+            if err.span.is_none() {
+                err.span = input.source_span;
+            }
+            return Err(err);
+        }
+    };
     if tmpl_kind == TmplKind::Struct {
         impl_everything(input.ast, buf);
     }
@@ -84,6 +95,8 @@ struct Generator<'a, 'h> {
     is_in_filter_block: usize,
     /// Set of called macros we are currently in. Used to prevent (indirect) recursions.
     seen_macros: Vec<(&'a Macro<'a>, Option<FileInfo<'a>>)>,
+    /// Will be set to true by the generator if the block in `self.input.block` was encountered.
+    block_encountered: bool,
 }
 
 impl<'a, 'h> Generator<'a, 'h> {
@@ -109,12 +122,13 @@ impl<'a, 'h> Generator<'a, 'h> {
             },
             is_in_filter_block,
             seen_macros: Vec::new(),
+            block_encountered: false,
         }
     }
 
     // Implement `Template` for the given context struct.
     fn impl_template(
-        mut self,
+        &mut self,
         buf: &mut Buffer,
         tmpl_kind: TmplKind<'a>,
     ) -> Result<usize, CompileError> {

rinja_derive/src/generator/node.rs

@@ -69,6 +69,7 @@ impl<'a> Generator<'a, '_> {
         );
         child.buf_writable = buf_writable;
         let res = callback(&mut child);
+        self.block_encountered |= child.block_encountered;
         Generator {
             locals: self.locals,
             buf_writable: self.buf_writable,
@@ -1013,8 +1014,11 @@ impl<'a> Generator<'a, '_> {
 
         self.write_buf_writable(ctx, buf)?;
 
-        let block_fragment_write =
-            self.input.block.map(|(block, _)| block) == name && self.buf_writable.discard;
+        let is_input_block = self.input.block.map(|(block, _)| block) == name;
+        if is_input_block {
+            self.block_encountered = true;
+        }
+        let block_fragment_write = is_input_block && self.buf_writable.discard;
         // Allow writing to the buffer if we're in the block fragment
         if block_fragment_write {
             self.buf_writable.discard = false;

testing/templates/no-block-with-base-template.txt

@@ -0,0 +1 @@
+{% extends "no-block-with-include-times-2.txt" %}

testing/templates/no-block-with-include-times-2.txt

@@ -0,0 +1,2 @@
+{% block also_also_not_a %}{% endblock %}
+{% include "no-block-with-include.txt" %}

testing/templates/no-block-with-include.txt

@@ -0,0 +1,2 @@
+{% block also_not_a %}{% endblock %}
+{% include "no-block.txt" %}

testing/templates/no-block.txt

@@ -0,0 +1 @@
+{% block not_a %}{% endblock %}

testing/tests/ui/no-block.rs

@@ -0,0 +1,28 @@
+use rinja::Template;
+
+#[derive(Template)]
+#[template(
+    ext = "txt",
+    source = "{% block not_a %}{% endblock %}",
+    block = "a"
+)]
+struct SourceTemplate;
+
+#[derive(Template)]
+#[template(path = "no-block.txt", block = "a")]
+struct PathTemplate;
+
+#[derive(Template)]
+#[template(path = "no-block-with-include.txt", block = "a")]
+struct NoBlockWithInclude;
+
+#[derive(Template)]
+#[template(path = "no-block-with-include-times-2.txt", block = "a")]
+struct NoBlockWithIncludeTimes2;
+
+#[derive(Template)]
+#[template(path = "no-block-with-base-template.txt", block = "a")]
+struct NoBlockWithBaseTemplate;
+
+fn main() {
+}

testing/tests/ui/no-block.stderr

@@ -0,0 +1,29 @@
+error: cannot find block `a`
+ --> tests/ui/no-block.rs:7:13
+  |
+7 |     block = "a"
+  |             ^^^
+
+error: cannot find block `a`
+  --> tests/ui/no-block.rs:12:43
+   |
+12 | #[template(path = "no-block.txt", block = "a")]
+   |                                           ^^^
+
+error: cannot find block `a`
+  --> tests/ui/no-block.rs:16:56
+   |
+16 | #[template(path = "no-block-with-include.txt", block = "a")]
+   |                                                        ^^^
+
+error: cannot find block `a`
+  --> tests/ui/no-block.rs:20:64
+   |
+20 | #[template(path = "no-block-with-include-times-2.txt", block = "a")]
+   |                                                                ^^^
+
+error: cannot find block `a`
+  --> tests/ui/no-block.rs:24:62
+   |
+24 | #[template(path = "no-block-with-base-template.txt", block = "a")]
+   |                                                              ^^^