[Clang] Fix warning for non std functions with name `infinity` (#123417)

Fix reporting diagnostic for non std functions that has the name
`infinity`

Fixes: #123231

1 files changed, 32 insertions, 15 deletions

diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index 881907a..c41164a 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -8454,26 +8454,43 @@ static bool IsInfOrNanFunction(StringRef calleeName, MathCheck Check) {
   llvm_unreachable("unknown MathCheck");
 }
 
+static bool IsInfinityFunction(const FunctionDecl *FDecl) {
+  if (FDecl->getName() != "infinity")
+    return false;
+
+  if (const CXXMethodDecl *MDecl = dyn_cast<CXXMethodDecl>(FDecl)) {
+    const CXXRecordDecl *RDecl = MDecl->getParent();
+    if (RDecl->getName() != "numeric_limits")
+      return false;
+
+    if (const NamespaceDecl *NSDecl =
+            dyn_cast<NamespaceDecl>(RDecl->getDeclContext()))
+      return NSDecl->isStdNamespace();
+  }
+
+  return false;
+}
+
 void Sema::CheckInfNaNFunction(const CallExpr *Call,
                                const FunctionDecl *FDecl) {
+  if (!FDecl->getIdentifier())
+    return;
+
   FPOptions FPO = Call->getFPFeaturesInEffect(getLangOpts());
-  bool HasIdentifier = FDecl->getIdentifier() != nullptr;
-  bool IsNaNOrIsUnordered =
-      IsStdFunction(FDecl, "isnan") || IsStdFunction(FDecl, "isunordered");
-  bool IsSpecialNaN =
-      HasIdentifier && IsInfOrNanFunction(FDecl->getName(), MathCheck::NaN);
-  if ((IsNaNOrIsUnordered || IsSpecialNaN) && FPO.getNoHonorNaNs()) {
+  if (FPO.getNoHonorNaNs() &&
+      (IsStdFunction(FDecl, "isnan") || IsStdFunction(FDecl, "isunordered") ||
+       IsInfOrNanFunction(FDecl->getName(), MathCheck::NaN))) {
     Diag(Call->getBeginLoc(), diag::warn_fp_nan_inf_when_disabled)
         << 1 << 0 << Call->getSourceRange();
-  } else {
-    bool IsInfOrIsFinite =
-        IsStdFunction(FDecl, "isinf") || IsStdFunction(FDecl, "isfinite");
-    bool IsInfinityOrIsSpecialInf =
-        HasIdentifier && ((FDecl->getName() == "infinity") ||
-                          IsInfOrNanFunction(FDecl->getName(), MathCheck::Inf));
-    if ((IsInfOrIsFinite || IsInfinityOrIsSpecialInf) && FPO.getNoHonorInfs())
-      Diag(Call->getBeginLoc(), diag::warn_fp_nan_inf_when_disabled)
-          << 0 << 0 << Call->getSourceRange();
+    return;
+  }
+
+  if (FPO.getNoHonorInfs() &&
+      (IsStdFunction(FDecl, "isinf") || IsStdFunction(FDecl, "isfinite") ||
+       IsInfinityFunction(FDecl) ||
+       IsInfOrNanFunction(FDecl->getName(), MathCheck::Inf))) {
+    Diag(Call->getBeginLoc(), diag::warn_fp_nan_inf_when_disabled)
+        << 0 << 0 << Call->getSourceRange();
   }
 }