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[clangd] Incorrect navigation caused by deducing this #116335

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ymyh opened this issue Nov 15, 2024 · 5 comments · May be fixed by #117841
Open

[clangd] Incorrect navigation caused by deducing this #116335

ymyh opened this issue Nov 15, 2024 · 5 comments · May be fixed by #117841
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clangd

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@ymyh
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ymyh commented Nov 15, 2024 

struct B
{
    template<typename Self>
    auto bar(this Self &&) 
    {
        return 0;
    }

    auto bar2(this B &&)
    {
        return 0;
    }
};

struct A
{
    auto foo()
    {
        return B{};
    }
};

auto baz(int n)
{
    return n;
}

int main()
{
    A a{};
    baz(a.foo().bar());

    A a2{};
    int n  = a2.foo().bar2();
}

incorrect navigation of a.foo and a to baz, a2.foo and a2 to n
@llvmbot
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llvmbot commented Nov 15, 2024

@llvm/issue-subscribers-clangd

Author: dayDreamingSaltyFish (ymyh)

```c++ struct B { template<typename Self> auto bar(this Self &&) { return 0; } 
auto bar2(this B &amp;&amp;)
{
    return 0;
}

};

struct A
{
auto foo()
{
return B{};
}
};

auto baz(int n)
{
return n;
}

int main()
{
A a{};
baz(a.foo().bar());

A a2{};
int n  = a2.foo().bar2();

}

incorrect navigation of a.foo and a to baz, a2.foo and a2 to n

</details>

@HighCommander4
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Slightly reduced:

struct S
{
    int bar(this S&);
};

int main()
{
    S waldo;
    int x = waldo.bar();
}

Go-to-def on waldo in waldo.bar() incorrectly goes to x.

@HighCommander4
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SelectionTree is incorrectly selecting the x.

Here is a SelectionTree trace:

Computing selection for </clangd-test/TestTU.cpp:7:19, col:24>
 skip: CXXRecordDecl </clangd-test/TestTU.cpp:2:9, line:4:9>
 push: FunctionDecl </clangd-test/TestTU.cpp:5:9, line:8:9>
  push: NestedNameSpecifierLoc <<invalid sloc>>
  pop: NestedNameSpecifierLoc
  skip: FunctionProtoTypeLoc </clangd-test/TestTU.cpp:5:9, col:18>
  push: CompoundStmt </clangd-test/TestTU.cpp:5:20, line:8:9>
   skip: DeclStmt </clangd-test/TestTU.cpp:6:11, col:18>
   push: DeclStmt </clangd-test/TestTU.cpp:7:11, col:30>
    push: VarDecl </clangd-test/TestTU.cpp:7:11, col:29>
     push: NestedNameSpecifierLoc <<invalid sloc>>
     pop: NestedNameSpecifierLoc
     skip: BuiltinTypeLoc </clangd-test/TestTU.cpp:7:11>
     skip: CallExpr </clangd-test/TestTU.cpp:7:25, col:29>
    pop: VarDecl
     hit selection: </clangd-test/TestTU.cpp:7:11, col:29>
   pop: DeclStmt
  pop: CompoundStmt
 pop: FunctionDecl
Built selection tree
 TranslationUnitDecl 
   FunctionDecl void foo()
     CompoundStmt { …
       DeclStmt int x = bar(waldo);
        .VarDecl int x = bar(waldo)

@HighCommander4
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Basically, the hit-testing algorithm skips the CallExpr node for waldo.bar() altogether, because CallExpr::getBeginLoc() returns the callee's begin loc, which is the bar token, so we think the waldo token falls outside of the CallExpr.

@HighCommander4 HighCommander4 mentioned this issue Nov 20, 2024
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@HighCommander4
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HighCommander4 commented Nov 20, 2024 •
edited
Loading

CallExpr::getBeginLoc() returns the callee's begin loc, which is the bar token

Let's start by seeing if we can get this fixed upstream in the AST: #116928

HighCommander4 added a commit to HighCommander4/llvm-project that referenced this issue Nov 27, 2024
@HighCommander4
[clang] Compute accurate begin location for CallExpr with explicit ob…
d5ef6d5 
…ject parameter

The explicit object parameter is written before the callee expression,
so the begin location should come from the explicit object parameter.

Fixes llvm#116335
@HighCommander4 HighCommander4 linked a pull request Nov 27, 2024 that will close this issue
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@HighCommander4 @EugeneZelenko @ymyh @llvmbot