Improve html! error messages. (#1192)

* Improve `html!` error messages.

* Improved some additional error messages.

* Improved error messages for iterables.

* Improved list error messages.

* Made a comment clearer.

* Updated an `html_tag` error message.

* Improved duplicate attribute error message.

* Updated tests to reflect updated error messages.

* Reformat code.

* Updated tests to reflect new error messages.

* Updated macro tests.

* Fix macro tests.

* Reformat code.

Author: teymour-aldridge

yew-macro/src/html_tree/html_component.rs

@@ -36,7 +36,7 @@ impl Parse for HtmlComponent {
             return match input.parse::<HtmlComponentClose>() {
                 Ok(close) => Err(syn::Error::new_spanned(
                     close,
-                    "this close tag has no corresponding open tag",
+                    "this closing tag has no corresponding opening tag",
                 )),
                 Err(err) => Err(err),
             };
@@ -57,7 +57,7 @@ impl Parse for HtmlComponent {
             if input.is_empty() {
                 return Err(syn::Error::new_spanned(
                     open,
-                    "this open tag has no corresponding close tag",
+                    "this opening tag has no corresponding closing tag",
                 ));
             }
             if let Some(ty) = HtmlComponentClose::peek(input.cursor()) {
@@ -376,7 +376,7 @@ impl Props {
     }
 
     fn collision_message() -> &'static str {
-        "Using special syntax `with props` along with named prop is not allowed. This rule does not apply to special `ref` prop"
+        "Using the `with props` syntax in combination with named props is not allowed (note: this does not apply to the `ref` prop)."
     }
 }
 
@@ -467,7 +467,7 @@ impl Parse for Props {
                 p.node_ref = node_ref;
                 p.key = key;
 
-                // alphabetize
+                // sort alphabetically
                 p.props.sort_by(|a, b| {
                     if a.label == b.label {
                         Ordering::Equal

yew-macro/src/html_tree/html_iterable.rs

@@ -26,7 +26,7 @@ impl Parse for HtmlIterable {
                 if err.to_string().starts_with("unexpected end of input") {
                     Err(syn::Error::new_spanned(
                         for_token,
-                        "expected expression after `for`",
+                        "expected an expression after the keyword `for`",
                     ))
                 } else {
                     Err(err)

yew-macro/src/html_tree/html_list.rs

@@ -28,7 +28,7 @@ impl Parse for HtmlList {
             return match input.parse::<HtmlListClose>() {
                 Ok(close) => Err(syn::Error::new_spanned(
                     close,
-                    "this close tag has no corresponding open tag",
+                    "this closing tag has no corresponding opening tag",
                 )),
                 Err(err) => Err(err),
             };
@@ -38,7 +38,7 @@ impl Parse for HtmlList {
         if !HtmlList::verify_end(input.cursor()) {
             return Err(syn::Error::new_spanned(
                 open,
-                "this open tag has no corresponding close tag",
+                "this opening tag has no corresponding closing tag",
             ));
         }
 

yew-macro/src/html_tree/html_tag/mod.rs

@@ -35,7 +35,7 @@ impl Parse for HtmlTag {
             return match input.parse::<HtmlTagClose>() {
                 Ok(close) => Err(syn::Error::new_spanned(
                     close,
-                    "this close tag has no corresponding open tag",
+                    "this closing tag has no corresponding opening tag",
                 )),
                 Err(err) => Err(err),
             };
@@ -56,7 +56,7 @@ impl Parse for HtmlTag {
             if input.is_empty() {
                 return Err(syn::Error::new_spanned(
                     open,
-                    "this open tag has no corresponding close tag",
+                    "this opening tag has no corresponding closing tag",
                 ));
             }
             if let Some(next_close_tag_name) = HtmlTagClose::peek(input.cursor()) {

yew-macro/src/html_tree/html_tag/tag_attributes.rs

@@ -177,7 +177,7 @@ impl Parse for TagAttributes {
                 let label = &attributes[i + 1].label;
                 return Err(syn::Error::new_spanned(
                     label,
-                    format!("only one `{}` attribute allowed", label),
+                    format!("the attribute `{}` can only be specified once", label),
                 ));
             }
             i += 1;

yew-macro/src/html_tree/mod.rs

@@ -55,7 +55,7 @@ impl Parse for HtmlRoot {
             let stream: TokenStream = input.parse()?;
             Err(syn::Error::new_spanned(
                 stream,
-                "only one root html element allowed",
+                "only one root html element is allowed (hint: you can wrap multiple html elements in a fragment `<></>`)",
             ))
         } else {
             Ok(html_root)
@@ -73,7 +73,7 @@ impl ToTokens for HtmlRoot {
 impl Parse for HtmlTree {
     fn parse(input: ParseStream) -> Result<Self> {
         let html_type = HtmlTree::peek(input.cursor())
-            .ok_or_else(|| input.error("expected valid html element"))?;
+            .ok_or_else(|| input.error("expected a valid html element"))?;
         let html_tree = match html_type {
             HtmlType::Empty => HtmlTree::Empty,
             HtmlType::Component => HtmlTree::Component(Box::new(input.parse()?)),

yew-macro/tests/macro/html-component-fail.stderr

@@ -1,4 +1,4 @@
-error: this open tag has no corresponding close tag
+error: this opening tag has no corresponding closing tag
   --> $DIR/html-component-fail.rs:79:13
    |
 79 |     html! { <Child> };
@@ -30,7 +30,7 @@ error: unexpected token
    |
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: this open tag has no corresponding close tag
+error: this opening tag has no corresponding closing tag
   --> $DIR/html-component-fail.rs:83:13
    |
 83 |     html! { <Child with props > };
@@ -54,31 +54,31 @@ error: too many refs set
    |
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: Using special syntax `with props` along with named prop is not allowed. This rule does not apply to special `ref` prop
+error: Using the `with props` syntax in combination with named props is not allowed (note: this does not apply to the `ref` prop).
   --> $DIR/html-component-fail.rs:86:38
    |
 86 |     html! { <Child with props ref=() value=1 ref=() /> };
    |                                      ^^^^^
    |
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: Using special syntax `with props` along with named prop is not allowed. This rule does not apply to special `ref` prop
+error: Using the `with props` syntax in combination with named props is not allowed (note: this does not apply to the `ref` prop).
   --> $DIR/html-component-fail.rs:87:31
    |
 87 |     html! { <Child with props value=1 ref=()  ref=() /> };
    |                               ^^^^^
    |
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: Using special syntax `with props` along with named prop is not allowed. This rule does not apply to special `ref` prop
+error: Using the `with props` syntax in combination with named props is not allowed (note: this does not apply to the `ref` prop).
   --> $DIR/html-component-fail.rs:88:28
    |
 88 |     html! { <Child value=1 with props  ref=()  ref=() /> };
    |                            ^^^^
    |
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: Using special syntax `with props` along with named prop is not allowed. This rule does not apply to special `ref` prop
+error: Using the `with props` syntax in combination with named props is not allowed (note: this does not apply to the `ref` prop).
   --> $DIR/html-component-fail.rs:89:35
    |
 89 |     html! { <Child value=1 ref=() with props ref=() /> };
@@ -102,15 +102,15 @@ error: unexpected token
    |
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: Using special syntax `with props` along with named prop is not allowed. This rule does not apply to special `ref` prop
+error: Using the `with props` syntax in combination with named props is not allowed (note: this does not apply to the `ref` prop).
   --> $DIR/html-component-fail.rs:93:28
    |
 93 |     html! { <Child value=1 with props /> };
    |                            ^^^^
    |
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: Using special syntax `with props` along with named prop is not allowed. This rule does not apply to special `ref` prop
+error: Using the `with props` syntax in combination with named props is not allowed (note: this does not apply to the `ref` prop).
   --> $DIR/html-component-fail.rs:94:31
    |
 94 |     html! { <Child with props value=1 /> };
@@ -150,39 +150,39 @@ error: too many refs set
     |
     = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: this close tag has no corresponding open tag
+error: this closing tag has no corresponding opening tag
    --> $DIR/html-component-fail.rs:106:13
     |
 106 |     html! { </Child> };
     |             ^^^^^^^^
     |
     = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: this open tag has no corresponding close tag
+error: this opening tag has no corresponding closing tag
    --> $DIR/html-component-fail.rs:107:13
     |
 107 |     html! { <Child><Child></Child> };
     |             ^^^^^^^
     |
     = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: only one root html element allowed
+error: only one root html element is allowed (hint: you can wrap multiple html elements in a fragment `<></>`)
    --> $DIR/html-component-fail.rs:108:28
     |
 108 |     html! { <Child></Child><Child></Child> };
     |                            ^^^^^^^^^^^^^^^
     |
     = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: this close tag has no corresponding open tag
+error: this closing tag has no corresponding opening tag
    --> $DIR/html-component-fail.rs:117:30
     |
 117 |     html! { <Generic<String>></Generic> };
     |                              ^^^^^^^^^^
     |
     = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: this close tag has no corresponding open tag
+error: this closing tag has no corresponding opening tag
    --> $DIR/html-component-fail.rs:118:30
     |
 118 |     html! { <Generic<String>></Generic<Vec<String>>> };

yew-macro/tests/macro/html-iterable-fail.stderr

@@ -1,4 +1,4 @@
-error: expected expression after `for`
+error: expected an expression after the keyword `for`
  --> $DIR/html-iterable-fail.rs:4:13
   |
 4 |     html! { for };

yew-macro/tests/macro/html-list-fail.stderr

@@ -1,52 +1,52 @@
-error: this open tag has no corresponding close tag
+error: this opening tag has no corresponding closing tag
  --> $DIR/html-list-fail.rs:4:13
   |
 4 |     html! { <> };
   |             ^^
   |
   = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: this close tag has no corresponding open tag
+error: this closing tag has no corresponding opening tag
  --> $DIR/html-list-fail.rs:5:13
   |
 5 |     html! { </> };
   |             ^^^
   |
   = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: this open tag has no corresponding close tag
+error: this opening tag has no corresponding closing tag
  --> $DIR/html-list-fail.rs:6:13
   |
 6 |     html! { <><> };
   |             ^^
   |
   = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: this close tag has no corresponding open tag
+error: this closing tag has no corresponding opening tag
  --> $DIR/html-list-fail.rs:7:13
   |
 7 |     html! { </></> };
   |             ^^^
   |
   = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: this open tag has no corresponding close tag
+error: this opening tag has no corresponding closing tag
  --> $DIR/html-list-fail.rs:8:13
   |
 8 |     html! { <><></> };
   |             ^^
   |
   = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: only one root html element allowed
+error: only one root html element is allowed (hint: you can wrap multiple html elements in a fragment `<></>`)
  --> $DIR/html-list-fail.rs:9:18
   |
 9 |     html! { <></><></> };
   |                  ^^^^^
   |
   = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: expected valid html element
+error: expected a valid html element
   --> $DIR/html-list-fail.rs:10:15
    |
 10 |     html! { <>invalid</> };
@@ -62,7 +62,7 @@ error: unexpected end of input, expected expression
    |
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: this open tag has no corresponding close tag
+error: this opening tag has no corresponding closing tag
   --> $DIR/html-list-fail.rs:12:13
    |
 12 |     html! { <key="key".to_string()>invalid</key>}

yew-macro/tests/macro/html-node-fail.stderr

@@ -1,4 +1,4 @@
-error: only one root html element allowed
+error: only one root html element is allowed (hint: you can wrap multiple html elements in a fragment `<></>`)
  --> $DIR/html-node-fail.rs:4:21
   |
 4 |     html! { "valid" "invalid" };