[PATCH] D22871: Fix incorrect -Wtautological-constant-out-of-range warnings with enums

[Ismail Badawi via cfe-commits]

ibadawi created this revision.
ibadawi added reviewers: majnemer, rjmccall.
ibadawi added a subscriber: cfe-commits.

This is a proposed fix for bug 16154 (https://llvm.org/bugs/show_bug.cgi?id=16154) -- it was tentatively fixed in r183084 but had the fix was backed out in r183575 because the approach taken wrongly affected the behavior or other warnings.

https://reviews.llvm.org/D22871

Files:
  lib/Sema/SemaChecking.cpp
  test/Sema/outof-range-constant-compare.c

Index: test/Sema/outof-range-constant-compare.c
===================================================================
--- test/Sema/outof-range-constant-compare.c
+++ test/Sema/outof-range-constant-compare.c
@@ -147,3 +147,15 @@
 
     return 1;
 }
+
+typedef enum {
+  alpha = 0,
+  bravo,
+  charlie,
+  delta,
+  echo
+} named_t;
+
+static int bar(named_t foo) {
+  return foo > 42;
+}
Index: lib/Sema/SemaChecking.cpp
===================================================================
--- lib/Sema/SemaChecking.cpp
+++ lib/Sema/SemaChecking.cpp
@@ -7075,6 +7075,12 @@
     return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger());
   }
 
+  /// Returns the "target" range of a given integral type.
+  static IntRange forTargetOfType(ASTContext &C, QualType T) {
+    return forTargetOfCanonicalType(C,
+                                    T->getCanonicalTypeInternal().getTypePtr());
+  }
+
   /// Returns the "target" range of a canonical integral type, i.e.
   /// the range of values expressible in the type.
   ///
@@ -7492,7 +7498,10 @@
   QualType OtherT = Other->getType();
   if (const auto *AT = OtherT->getAs<AtomicType>())
     OtherT = AT->getValueType();
-  IntRange OtherRange = IntRange::forValueOfType(S.Context, OtherT);
+  IntRange OtherRange = S.getLangOpts().CPlusPlus
+                            ? IntRange::forValueOfType(S.Context, OtherT)
+                            : IntRange::forTargetOfType(S.Context, OtherT);
+
   unsigned OtherWidth = OtherRange.Width;
 
   bool OtherIsBooleanType = Other->isKnownToHaveBooleanValue();


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