[Sema] Suppress -Wformat diagnostics for bool types when printed using %hhd

Also, add a diagnostic under -Wformat for printing a boolean value as a
character.

rdar://54579473

Differential revision: https://reviews.llvm.org/D66856

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@372247 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 16 insertions, 0 deletions

diff --git a/lib/Sema/SemaChecking.cpp b/lib/Sema/SemaChecking.cpp
index c7639b4a40..af69c231f1 100644
--- a/lib/Sema/SemaChecking.cpp
+++ b/lib/Sema/SemaChecking.cpp
@@ -8109,6 +8109,22 @@ CheckPrintfHandler::checkFormatExpr(const analyze_printf::PrintfSpecifier &FS,
     ExprTy = TET->getUnderlyingExpr()->getType();
   }
 
+  // Diagnose attempts to print a boolean value as a character. Unlike other
+  // -Wformat diagnostics, this is fine from a type perspective, but it still
+  // doesn't make sense.
+  if (FS.getConversionSpecifier().getKind() == ConversionSpecifier::cArg &&
+      E->isKnownToHaveBooleanValue()) {
+    const CharSourceRange &CSR =
+        getSpecifierRange(StartSpecifier, SpecifierLen);
+    SmallString<4> FSString;
+    llvm::raw_svector_ostream os(FSString);
+    FS.toString(os);
+    EmitFormatDiagnostic(S.PDiag(diag::warn_format_bool_as_character)
+                             << FSString,
+                         E->getExprLoc(), false, CSR);
+    return true;
+  }
+
   const analyze_printf::ArgType::MatchKind Match =
       AT.matchesType(S.Context, ExprTy);
   bool Pedantic = Match == analyze_printf::ArgType::NoMatchPedantic;