Merge pull request #2805 from epage/validate_default

fix(derive): Type check `default_value_t`

clap_derive/src/attrs.rs

@@ -340,27 +340,28 @@ impl Attrs {
  VerbatimDocComment(ident) => self.verbatim_doc_comment = Some(ident),
 
  DefaultValueT(ident, expr) => {
+ let ty = if let Some(ty) = self.ty.as_ref() {
+ ty
+ } else {
+ abort!(
+ ident,
+ "#[clap(default_value_t)] (without an argument) can be used \
+ only on field level";
+
+ note = "see \
+ https://docs.rs/structopt/0.3.5/structopt/#magical-methods")
+ };
+
  let val = if let Some(expr) = expr {
  quote!(#expr)
  } else {
- let ty = if let Some(ty) = self.ty.as_ref() {
- ty
- } else {
- abort!(
- ident,
- "#[clap(default_value_t)] (without an argument) can be used \
- only on field level";
-
- note = "see \
- https://docs.rs/structopt/0.3.5/structopt/#magical-methods")
- };
  quote!(<#ty as ::std::default::Default>::default())
  };
 
  let val = quote_spanned!(ident.span()=> {
  clap::lazy_static::lazy_static! {
  static ref DEFAULT_VALUE: &'static str = {
- let val = #val;
+ let val: #ty = #val;
  let s = ::std::string::ToString::to_string(&val);
  ::std::boxed::Box::leak(s.into_boxed_str())
  };

clap_derive/tests/ui/default_value_t_invalid.rs

@@ -0,0 +1,21 @@
+// Copyright 2018 Guillaume Pinot (@TeXitoi) <texitoi@texitoi.eu>
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use clap::Clap;
+
+#[derive(Clap, Debug)]
+#[clap(name = "basic")]
+struct Opt {
+ #[clap(default_value_t = -10)]
+ value: u32,
+}
+
+fn main() {
+ let opt = Opt::parse();
+ println!("{:?}", opt);
+}

clap_derive/tests/ui/default_value_t_invalid.stderr

@@ -0,0 +1,7 @@
+error[E0600]: cannot apply unary operator `-` to type `u32`
+ --> $DIR/default_value_t_invalid.rs:14:30
+ |
+14 | #[clap(default_value_t = -10)]
+ | ^^^ cannot apply unary operator `-`
+ |
+ = note: unsigned values cannot be negated