[clang-tools-extra] [clang-tidy] Fix misc-unused-parameters on params with attrs (PR #122286)

[Utkarsh Saxena via cfe-commits]

================
@@ -26,6 +29,17 @@ bool isOverrideMethod(const FunctionDecl *Function) {
     return MD->size_overridden_methods() > 0 || MD->hasAttr<OverrideAttr>();
   return false;
 }
+
+bool hasAttrAfterParam(const SourceManager *SourceManager,
+                       const ParmVarDecl *Param) {
+  for (const auto *Attr : Param->attrs()) {
+    if (SourceManager->isBeforeInTranslationUnit(Param->getLocation(),
+                                                 Attr->getLocation())) {
+      return true;
+    }
+  }
+  return false;
+}
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usx95 wrote:

It is unfortunate that for declaration attributes we do not have the information that attr appeared before or after the decl.
I would argue, for simplicity, we filter out all annotated params irrespective of the position of attribute.

Dealing with raw source locations can quickly become problematic. For example with expanded locations:
```cpp
#define ANNOTATE_BEFORE(x) [[clang::lifetimebound]] x
#define ANNOTATE_AFTER(x) x [[clang::lifetimebound]]

int* foo(ANNOTATE_BEFORE(int* x)) {}
int* bar(ANNOTATE_AFTER(int* x)) {}
```
https://godbolt.org/z/brYMKfcxf
It is possible to make it work but I don't see the point of this complexity when we can have a simpler filter without much fallout

https://github.com/llvm/llvm-project/pull/122286