[cfe-dev] ASTMatcher unexpected result

[Hartogs Siegfried via cfe-dev]

Hi everyone,

I'm trying to use AST Matchers in clang-query to find single-depth for-loops,
i.e. for-loops that are neither contained in any other for-loop nor contain for-loops themselves.

Approach:
forStmt( unless(hasAncestor(forStmt())), unless(hasDescendant(forStmt())) )

In the following code, I want it to match only the loop in foo1, but unfortunately it also matches the loop in foo2.

void foo1(){ int n = 10; for(int i1=0; i1<n; i1++){ // dosomething(); } } void foo2(){ int n = 10; for(int i21=0; i21<n; i21++){ for(int i22=0; i22<n; i22++){ // dosomething(); } } }

Match #1:
~/cq.cpp:4:5: note: "root" binds here
    for(int i1=0; i1<n; i1++){
    ^~~~~~~~~~~~~~~~~~~~~~~~~~

Match #2:
~/cq.cpp:11:5: note: "root" binds here
    for(int i21=0; i21<n; i21++){
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
2 matches.

When I interchange "hasAncestor" and "hasDescendant" in the matcher, the second match changes:

Match #1:
~/cq.cpp:4:5: note: "root" binds here
    for(int i1=0; i1<n; i1++){
    ^~~~~~~~~~~~~~~~~~~~~~~~~~

Match #2:
~/cq.cpp:11:5: note: "root" binds here
    for(int i22=0; i21<n; i22++){
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
2 matches.

To me, it doesn't make sense why the result changes (implicit allOf() matcher's argument order shouldn't matter), but I don't understand why the matcher returns a loop from foo2 in the first place.

Best regards,
Siegfried Hartogs
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