[cfe-dev] [clang-tidy] problem finding AST matcher for nested implicit const-cast

[Artem Dergachev via cfe-dev]

The original matcher looks pretty weird to me, as the last anyOf() case, 
namely "hasDescendant(BeginCallMatcher)", already matches more than all 
previous anyOf() cases.

On 5/7/19 1:06 PM, Torbjörn Klatt via cfe-dev wrote:
> Hi all,
>
> I'm trying to fix the clang-tidy bug 35082 [1] as a starter for getting into LLVM development and contribution.
>
> I think, I've tracked down the issue to
>
> clang-tidy/modernize/LoopConvertCheck.cpp:123ff: clang::tidy::modernize::makeIteratorLoopMatcher()
> ```
>    DeclarationMatcher InitDeclMatcher =
>        varDecl(hasInitializer(anyOf(ignoringParenImpCasts(BeginCallMatcher),
>                                     materializeTemporaryExpr(
>                                         ignoringParenImpCasts(BeginCallMatcher)),
>                                     hasDescendant(BeginCallMatcher))))
>            .bind(InitVarName);
> ```
> The definition of `InitDeclMatcher` seems to not match  the AST tree
> ```
>    |-ForStmt
>    | |-DeclStmt
>    | | `-VarDecl
>    | |   `-ExprWithCleanups
>    | |     `-ImplicitCastExpr
>    | |       `-CXXConstructExpr
>    | |         `-MaterializeTemporaryExpr
>    | |           `-ImplicitCastExpr
>    | |             `-CXXMemberCallExpr
>    | |               `-MemberExpr
>    | |                 `-DeclRefExpr
> ```
> of
> ```
> std::vector<int> vec{1, 2, 3, 4, 5};
> for(std::vector<int>::const_iterator i = vec.begin(); i != vec.end(); ++i) { ... }
> ```
>
> In my naivety, I tried to include the following into the `anyOf`:
> ```
>                                     exprWithCleanups(
>                                         ignoringParenImpCasts(
>                                             cxxConstructExpr(
>                                                 materializeTemporaryExpr(
>                                                     ignoringParenImpCasts(
>                                                         BeginCallMatcher))))),
> ```
> mimicking the specific AST tree. Without luck.
>
> I browsed through include/clang/ASTMatchers.h for better suited matchers, but couldn't find any.
>
> What important detail am I missing?
>
> Best
> Torbjörn
>
> [1]: https://bugs.llvm.org/show_bug.cgi?id=35082
>
>
>
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