[clangd] Hide inlay hints when using a macro as a calling argument that with a param comment

We don't want to produce inlay hints for arguments for which
user has left param name comments. But we're not decomposing
location of the parameter correctly at the moment because the
location we've passed into `SM.getDecomposedLoc` is not always
FileID.

Fixes clangd/clangd#1495

Reviewed By: nridge

Differential Revision: https://reviews.llvm.org/D144074

Author: zyn0217

clang-tools-extra/clangd/InlayHints.cpp

@@ -516,8 +516,8 @@ class InlayHintVisitor : public RecursiveASTVisitor<InlayHintVisitor> {
   // at the end.
   bool isPrecededByParamNameComment(const Expr *E, StringRef ParamName) {
     auto &SM = AST.getSourceManager();
-    auto ExprStartLoc = SM.getTopMacroCallerLoc(E->getBeginLoc());
-    auto Decomposed = SM.getDecomposedLoc(ExprStartLoc);
+    auto FileLoc = SM.getFileLoc(E->getBeginLoc());
+    auto Decomposed = SM.getDecomposedLoc(FileLoc);
     if (Decomposed.first != MainFileID)
       return false;
 

clang-tools-extra/clangd/unittests/InlayHintTests.cpp

@@ -1050,9 +1050,15 @@ TEST(ParameterHints, ParamNameComment) {
     void bar() {
       foo(/*param*/42);
       foo( /* param = */ 42);
+#define X 42
+#define Y X
+#define Z(...) Y
+      foo(/*param=*/Z(a));
+      foo($macro[[Z(a)]]);
       foo(/* the answer */$param[[42]]);
     }
   )cpp",
+                       ExpectedHint{"param: ", "macro"},
                        ExpectedHint{"param: ", "param"});
 }