clang-tidy/bugprone: match dependent types in

unused-local-non-trivial-variable

Also add the ability to match against template specializations, this can
be useful if you want all std::future types to be matched, no matter
what type is held within the future.

Signed-off-by: Tyler Rockwood <[email protected]>

Author: rockwotj

clang-tools-extra/clang-tidy/bugprone/UnusedLocalNonTrivialVariableCheck.cpp

@@ -60,9 +60,13 @@ void UnusedLocalNonTrivialVariableCheck::registerMatchers(MatchFinder *Finder) {
       varDecl(isLocalVarDecl(), unless(isReferenced()),
               unless(isExceptionVariable()), hasLocalStorage(), isDefinition(),
               unless(hasType(isReferenceType())), unless(hasType(isTrivial())),
-              hasType(hasUnqualifiedDesugaredType(recordType(hasDeclaration(
-                  recordDecl(matchesAnyListedName(IncludeTypes),
-                             unless(matchesAnyListedName(ExcludeTypes))))))))
+              hasType(hasUnqualifiedDesugaredType(
+                  anyOf(recordType(hasDeclaration(namedDecl(
+                            matchesAnyListedName(IncludeTypes),
+                            unless(matchesAnyListedName(ExcludeTypes))))),
+                        templateSpecializationType(hasDeclaration(namedDecl(
+                            matchesAnyListedName(IncludeTypes),
+                            unless(matchesAnyListedName(ExcludeTypes)))))))))
           .bind("var"),
       this);
 }

clang-tools-extra/test/clang-tidy/checkers/bugprone/unused-local-non-trivial-variable.cpp

@@ -73,6 +73,10 @@ T qux(T Generic) {
     async::Future<Units> MustBeUsed;
     // CHECK-MESSAGES: :[[@LINE-1]]:26: warning: unused local variable 'MustBeUsed' of type 'async::Future<Units>' [bugprone-unused-local-non-trivial-variable]
     PendingA.get();
+    async::Future<T> TemplateType;
+    // CHECK-MESSAGES: :[[@LINE-1]]:22: warning: unused local variable 'TemplateType' of type 'async::Future<T>' [bugprone-unused-local-non-trivial-variable]
+    a::Future<T> AliasTemplateType;
+    // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: unused local variable 'AliasTemplateType' of type 'a::Future<T>' (aka 'Future<type-parameter-0-0>') [bugprone-unused-local-non-trivial-variable]
     return Generic;
 }