[CLANG] Fix INF/NAN warning.

clang/include/clang/Basic/DiagnosticCommonKinds.td

@@ -73,7 +73,7 @@ def warn_pragma_debug_unexpected_argument : Warning<
 def warn_fp_nan_inf_when_disabled : Warning<
   "use of %select{infinity|NaN}0%select{| via a macro}1 is undefined behavior "
   "due to the currently enabled floating-point options">,
-  InGroup<DiagGroup<"nan-infinity-disabled">>;
+  InGroup<DiagGroup<"NanInfDisabledDocs">>;
 }
 
 // Parse && Sema

clang/include/clang/Basic/DiagnosticDocs.td

@@ -87,3 +87,10 @@ program by treating all string literals as having type ``const char *``
 instead of ``char *``. This can cause unexpected behaviors with type-sensitive
 constructs like ``_Generic``.
 }];
+
+defvar NanInfDisabledDocs = [{
+This warning is enabled when source code using the macros INFINITY and/or NAN
+is compiled with floating-point options preventing these two values. This can
+lead to undefined behavior. Some command line combinations order and pragmas
+may have an impact and a warning can be generated when not expected.
+}];

clang/include/clang/Lex/Preprocessor.h

@@ -2838,7 +2838,8 @@ class Preprocessor {
     return AnnotationInfos.find(II)->second;
   }
 
-  void emitMacroExpansionWarnings(const Token &Identifier) const {
+  void emitMacroExpansionWarnings(const Token &Identifier,
+                                  bool IsIfnDef = false) const {
     IdentifierInfo *Info = Identifier.getIdentifierInfo();
     if (Info->isDeprecatedMacro())
       emitMacroDeprecationWarning(Identifier);
@@ -2847,12 +2848,12 @@ class Preprocessor {
         !SourceMgr.isInMainFile(Identifier.getLocation()))
       emitRestrictExpansionWarning(Identifier);
 
-    if (Info->getName() == "INFINITY")
-      if (getLangOpts().NoHonorInfs)
+    if (!IsIfnDef) {
+      if (Info->getName() == "INFINITY" && getLangOpts().NoHonorInfs)
         emitRestrictInfNaNWarning(Identifier, 0);
-    if (Info->getName() == "NAN")
-      if (getLangOpts().NoHonorNaNs)
+      if (Info->getName() == "NAN" && getLangOpts().NoHonorNaNs)
         emitRestrictInfNaNWarning(Identifier, 1);
+    }
   }
 
   static void processPathForFileMacro(SmallVectorImpl<char> &Path,

clang/lib/Lex/PPDirectives.cpp

@@ -3288,7 +3288,7 @@ void Preprocessor::HandleIfdefDirective(Token &Result,
     return;
   }
 
-  emitMacroExpansionWarnings(MacroNameTok);
+  emitMacroExpansionWarnings(MacroNameTok, /*IsIfnDef=*/true);
 
   // Check to see if this is the last token on the #if[n]def line.
   CheckEndOfDirective(isIfndef ? "ifndef" : "ifdef");

clang/lib/Lex/PPExpressions.cpp

@@ -133,7 +133,9 @@ static bool EvaluateDefined(PPValue &Result, Token &PeekTok, DefinedTracker &DT,
   Result.Val.setIsUnsigned(false); // Result is signed intmax_t.
   DT.IncludedUndefinedIds = !Macro;
 
-  PP.emitMacroExpansionWarnings(PeekTok);
+  PP.emitMacroExpansionWarnings(
+      PeekTok,
+      (II->getName() == "INFINITY" || II->getName() == "NAN") ? true : false);
 
   // If there is a macro, mark it used.
   if (Result.Val != 0 && ValueLive)

clang/test/Sema/warn-infinity-nan-disabled-lnx.cpp

@@ -1,13 +1,19 @@
-// RUN: %clang_cc1 -x c++ -verify=no-inf-no-nan -triple powerpc64le-unknown-unknown %s \
-// RUN: -menable-no-infs -menable-no-nans
+// RUN: %clang_cc1 -x c++ -verify=no-inf-no-nan \
+// RUN: -triple powerpc64le-unknown-unknown %s -menable-no-infs \
+// RUN: -menable-no-nans -std=c++23
 
-// RUN: %clang_cc1 -x c++ -verify=no-fast -triple powerpc64le-unknown-unknown %s
+// RUN: %clang_cc1 -x c++ -verify=no-inf-no-nan \
+// RUN: -triple powerpc64le-unknown-unknown %s -menable-no-infs \
+// RUN: -menable-no-nans -funsafe-math-optimizations -std=c++23
+
+// RUN: %clang_cc1 -x c++ -verify=no-fast -triple powerpc64le-unknown-unknown \
+// RUN: %s -std=c++23
 
 // RUN: %clang_cc1 -x c++ -verify=no-inf -triple powerpc64le-unknown-unknown %s \
-// RUN: -menable-no-infs
+// RUN: -menable-no-infs -std=c++23
 
 // RUN: %clang_cc1 -x c++ -verify=no-nan -triple powerpc64le-unknown-unknown %s \
-// RUN: -menable-no-nans
+// RUN: -menable-no-nans -std=c++23
 
 // no-fast-no-diagnostics
 
@@ -133,13 +139,31 @@ int compareit(float a, float b) {
 // no-inf-warning@+1 {{use of infinity is undefined behavior due to the currently enabled floating-point options}}
   p = __builtin_isfinite(a);
 
-  // These should NOT warn, since they are not using NaN or infinity.
+// These should NOT warn, since they are not using NaN or infinity.
   j = a > 1.1;
   j = b < 1.1;
   j = a >= 1.1;
   j = b <= 1.1;
   j = isunorderedf(a, b);
 
+#ifndef INFINITY
+  j = a;
+#endif
+#ifndef NAN
+  j = b;
+#endif
+#ifdef INFINITY
+  j = a;
+#endif
+#ifdef NAN
+  j = b;
+#endif
+#if defined(INFINITY)
+  j = a;
+#elifndef(INFINITY)
+  j = b;
+#endif
+
 // no-inf-no-nan-warning@+4 {{use of NaN via a macro is undefined behavior due to the currently enabled floating-point options}}
 // no-inf-no-nan-warning@+3 {{use of NaN is undefined behavior due to the currently enabled floating-point options}}
 // no-nan-warning@+2 {{use of NaN via a macro is undefined behavior due to the currently enabled floating-point options}}
@@ -173,4 +197,4 @@ int compareit(float a, float b) {
   j = numeric_limits<float>::infinity();
   return 0;
 
-}  
+}

clang/test/Sema/warn-infinity-nan-disabled-win.cpp

@@ -1,16 +1,22 @@
 // Use of NAN macro will trigger a warning "infinity defined in macro" because
 // on Windows the NAN macro is defined using INFINITY. See below.
 
-// RUN: %clang_cc1 -x c++ -verify=no-inf-no-nan -triple powerpc64le-unknown-unknown %s \
-// RUN: -menable-no-infs -menable-no-nans
+// RUN: %clang_cc1 -x c++ -verify=no-inf-no-nan \
+// RUN: -triple powerpc64le-unknown-unknown %s -menable-no-infs \
+// RUN: -menable-no-nans -std=c++23
 
-// RUN: %clang_cc1 -x c++ -verify=no-fast -triple powerpc64le-unknown-unknown %s
+// RUN: %clang_cc1 -x c++ -verify=no-inf-no-nan \
+// RUN: -triple powerpc64le-unknown-unknown %s -menable-no-infs \
+// RUN: -menable-no-nans -funsafe-math-optimizations -std=c++23
+
+// RUN: %clang_cc1 -x c++ -verify=no-fast -triple powerpc64le-unknown-unknown \
+// RUN: %s -std=c++23
 
 // RUN: %clang_cc1 -x c++ -verify=no-inf -triple powerpc64le-unknown-unknown %s \
-// RUN: -menable-no-infs
+// RUN: -menable-no-infs -std=c++23
 
 // RUN: %clang_cc1 -x c++ -verify=no-nan -triple powerpc64le-unknown-unknown %s \
-// RUN: -menable-no-nans
+// RUN: -menable-no-nans -std=c++23
 
 // no-fast-no-diagnostics
 
@@ -136,13 +142,31 @@ int compareit(float a, float b) {
 // no-inf-warning@+1 {{use of infinity is undefined behavior due to the currently enabled floating-point options}}
   p = __builtin_isfinite(a);
 
-  // These should NOT warn, since they are not using NaN or infinity.
+// These should NOT warn, since they are not using NaN or infinity.
   j = a > 1.1;
   j = b < 1.1;
   j = a >= 1.1;
   j = b <= 1.1;
   j = isunorderedf(a, b);
 
+#ifndef INFINITY
+  j = a;
+#endif
+#ifndef NAN
+  j = b;
+#endif
+#ifdef INFINITY
+  j = a;
+#endif
+#ifdef NAN
+  j = b;
+#endif
+#if defined(INFINITY)
+  j = a;
+#elifndef(INFINITY)
+  j = b;
+#endif
+
 // no-inf-no-nan-warning@+4 {{use of infinity via a macro is undefined behavior due to the currently enabled floating-point option}}
 // no-inf-no-nan-warning@+3 {{use of NaN via a macro is undefined behavior due to the currently enabled floating-point options}}
 // no-inf-warning@+2 {{use of infinity via a macro is undefined behavior due to the currently enabled floating-point options}}
@@ -176,4 +200,4 @@ int compareit(float a, float b) {
   j = numeric_limits<float>::infinity();
   return 0;
 
-}  
+}