Don't insert a duplicate trailing comma in gluon_codegen
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Currently, `gluon_codegen` unconditionall inserts a comma after the user-provided `where` clause. However, the `where` clause may already have a trailing comma, which will result in an unparsable `TokenStream` being generated. The `AliasRef` struct would be affected by this bug, but a rustc bug causes the exact parsed `TokenStream` to be lost in some cases (see rust-lang/rust#43081) - in this case, due to the presence of `#[cfg_attr]`. When PR rust-lang/rust#76130 is merged, the exact parsed `TokenStream` will be passed to proc-macros in more cases, exposing this bug.
Aaron1011
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Currently,
gluon_codegenunconditionall inserts a comma after theuser-provided
whereclause. However, thewhereclause may alreadyhave a trailing comma, which will result in an unparsable
TokenStreambeing generated.
The
AliasRefstruct would be affected by this bug, but a rustc bugcauses the exact parsed
TokenStreamto be lost in some cases(see rust-lang/rust#43081) - in this case, due
to the presence of
#[cfg_attr].When PR rust-lang/rust#76130 is merged, the
exact parsed
TokenStreamwill be passed to proc-macros in more cases,exposing this bug.