alexfh added inline comments.
================
Comment at: clang-tools-extra/clang-tidy/misc/InitLocalVariablesCheck.cpp:21
+ Finder->addMatcher(
+ varDecl(unless(hasInitializer(anything()))).bind("vardecl"), this);
+}
----------------
jpakkane wrote:
> alexfh wrote:
> > jpakkane wrote:
> > > alexfh wrote:
> > > > jpakkane wrote:
> > > > > alexfh wrote:
> > > > > > I believe, this should skip matches within template instantiations.
> > > > > > Consider this code:
> > > > > > ```
> > > > > > template<typename T>
> > > > > > void f(T) { T t; }
> > > > > > void g() {
> > > > > > f(0);
> > > > > > f(0.0);
> > > > > > }
> > > > > > ```
> > > > > >
> > > > > > What will the fix be?
> > > > > I tested with the following function:
> > > > >
> > > > >
> > > > > ```
> > > > > template<typename T>
> > > > > void template_test_function() {
> > > > > T t;
> > > > > int uninitialized;
> > > > > }
> > > > > ```
> > > > >
> > > > > Currently it warns on the "uninitialized" variable regardless of
> > > > > whether the template is instantiated or not. If you call it with an
> > > > > int type, it will warn about variable t being uninitialized. If you
> > > > > call it with a, say, struct type, there is no warnings. Is this a
> > > > > reasonable approach?
> > > > And what happens, if there are multiple instantiations of the same
> > > > template, each of them requiring a different fix? Can you try the check
> > > > with my example above (and maybe also add `f("");`inside `g()`). I
> > > > believe, the check will produce multiple warnings with conflicting
> > > > fixes (and each of them will be wrong, btw).
> > > Interestingly it does warn about it, but only once, even if you have two
> > > different template specializations.
> > >
> > > I tried to suppress this warning when the type being instantiated is a
> > > template argument type but no matter what I tried I could not get this to
> > > work. Is there a way to get this information from the MatchedDecl object
> > > or does one need to do something more complicated like going up the AST
> > > until a function definition is found and checking if it is a template
> > > specialization (presumably with TemplatedKind)? Any help would be
> > > appreciated.
> > If there are multiple warnings with the same message at the same location
> > (clang-tidy/ClangTidyDiagnosticConsumer.cpp:745), they will be
> > deduplicated. Thus, a random fix will probably be suggested. The proper way
> > to filter out matches in template instantiations is to add
> > `unless(isInTemplateInstantiation())` to the matcher.
> I tried to make this work but I just could not combine statement and
> declaration matching in a reliable way. Matching a statement that is not in a
> template declaration can be done, as well as matching a declaration without
> intial value, but combining those two into one is hard. After trying many,
> many things the best I could come up with was this:
>
> ```
> declStmt(containsDeclaration(0,
> varDecl(unless(hasInitializer(anything()))).bind("vardecl"))), this)
> ```
>
> The problem is that `containsDeclaration` takes an integer denoting how
> manyth declaration should be processed. Manually adding matchers for, say, 0,
> 1, 2, 3 and 4 works and does the right thing but fails if anyone has an
> uninitialized variable in the sixth location, things will silently fail.
>
> The weird thing is that if you do the matching this way, you don't need to
> filter out things with `unless(isInTemplateInstantiation())`. Maybe
> statements are handled differently from declarations?
I was struggling to understand, why you want to match a statement, but then I
figured out that I should have been more precise: while
`isInTemplateInstantiation` only works for `Stmt`s, there's a related matcher
that works for `Decl`s: `isInstantiated`. See
clang/include/clang/ASTMatchers/ASTMatchers.h:5187. In general, looking into
this header can be useful, if you want to find a matcher that you can vaguely
describe (e.g. when looking for something related to instantiations, you can
search for the relevant substring and find this and a bunch of other matchers).
Sorry for the confusion. I hope, the suggestion helps.
Repository:
rCTE Clang Tools Extra
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D64671/new/
https://reviews.llvm.org/D64671
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