Index: gcc/c-family/c-common.c
===================================================================
--- gcc/c-family/c-common.c	(revision 239971)
+++ gcc/c-family/c-common.c	(working copy)
@@ -4617,7 +4617,22 @@ c_common_truthvalue_conversion (location_t locatio
 	return c_common_truthvalue_conversion (location,
 					       TREE_OPERAND (expr, 0));
 
+    case LSHIFT_EXPR:
+      if (TREE_CODE (TREE_TYPE (expr)) == INTEGER_TYPE
+	  && !TYPE_UNSIGNED (TREE_TYPE (expr)))
+	warning_at (EXPR_LOCATION (expr), OPT_Wint_in_bool_context,
+		    "<< on signed integer in boolean context");
+      break;
+
     case COND_EXPR:
+      if (TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST
+	  && TREE_CODE (TREE_OPERAND (expr, 2)) == INTEGER_CST
+	  && !integer_zerop (TREE_OPERAND (expr, 1))
+	  && !integer_zerop (TREE_OPERAND (expr, 2))
+	  && (!integer_onep (TREE_OPERAND (expr, 1))
+	      || !integer_onep (TREE_OPERAND (expr, 2))))
+	warning_at (EXPR_LOCATION (expr), OPT_Wint_in_bool_context,
+		    "?: using integer constants in boolean context");
       /* Distribute the conversion into the arms of a COND_EXPR.  */
       if (c_dialect_cxx ())
 	{
Index: gcc/c-family/c.opt
===================================================================
--- gcc/c-family/c.opt	(revision 239971)
+++ gcc/c-family/c.opt	(working copy)
@@ -525,6 +525,10 @@ Wint-conversion
 C ObjC Var(warn_int_conversion) Init(1) Warning
 Warn about incompatible integer to pointer and pointer to integer conversions.
 
+Wint-in-bool-context
+C ObjC C++ ObjC++ Var(warn_int_in_bool_context) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
+Warn for suspicious integer expressions in boolean context.
+
 Wint-to-pointer-cast
 C ObjC C++ ObjC++ Var(warn_int_to_pointer_cast) Init(1) Warning
 Warn when there is a cast to a pointer from an integer of a different size.
Index: gcc/cp/parser.c
===================================================================
--- gcc/cp/parser.c	(revision 239971)
+++ gcc/cp/parser.c	(working copy)
@@ -11172,7 +11172,7 @@ cp_parser_condition (cp_parser* parser)
 	{
 	  tree pushed_scope;
 	  bool non_constant_p;
-	  bool flags = LOOKUP_ONLYCONVERTING;
+	  int flags = LOOKUP_ONLYCONVERTING;
 
 	  /* Create the declaration.  */
 	  decl = start_decl (declarator, &type_specifiers,
Index: gcc/doc/invoke.texi
===================================================================
--- gcc/doc/invoke.texi	(revision 239971)
+++ gcc/doc/invoke.texi	(working copy)
@@ -273,7 +273,7 @@ Objective-C and Objective-C++ Dialects}.
 -Wframe-larger-than=@var{len} -Wno-free-nonheap-object -Wjump-misses-init @gol
 -Wignored-qualifiers  -Wignored-attributes  -Wincompatible-pointer-types @gol
 -Wimplicit  -Wimplicit-function-declaration  -Wimplicit-int @gol
--Winit-self  -Winline  -Wno-int-conversion @gol
+-Winit-self  -Winline  -Wno-int-conversion  -Wint-in-bool-context @gol
 -Wno-int-to-pointer-cast -Winvalid-memory-model -Wno-invalid-offsetof @gol
 -Winvalid-pch -Wlarger-than=@var{len} @gol
 -Wlogical-op -Wlogical-not-parentheses -Wlong-long @gol
@@ -5816,6 +5816,15 @@ warning about it.
 The restrictions on @code{offsetof} may be relaxed in a future version
 of the C++ standard.
 
+@item -Wint-in-bool-context
+@opindex Wint-in-bool-context
+@opindex Wno-int-in-bool-context
+Warn for suspicious use of integer values where boolean values are expected,
+such as conditional expressions (?:) using non-boolean integer constants in
+boolean context, like @code{if (a <= b ? 2 : 3)}.  Or left shifting of a
+signed integer in boolean context, like @code{for (a = 0; 1 << a; a++);}.
+This warning is enabled by @option{-Wall}.
+
 @item -Wno-int-to-pointer-cast
 @opindex Wno-int-to-pointer-cast
 @opindex Wint-to-pointer-cast
Index: gcc/dwarf2out.c
===================================================================
--- gcc/dwarf2out.c	(revision 239971)
+++ gcc/dwarf2out.c	(working copy)
@@ -2051,9 +2051,9 @@ output_loc_operands (dw_loc_descr_ref loc, int for
 	/* Make sure the offset has been computed and that we can encode it as
 	   an operand.  */
 	gcc_assert (die_offset > 0
-		    && die_offset <= (loc->dw_loc_opc == DW_OP_call2)
+		    && die_offset <= (loc->dw_loc_opc == DW_OP_call2
 				     ? 0xffff
-				     : 0xffffffff);
+				     : 0xffffffff));
 	dw2_asm_output_data ((loc->dw_loc_opc == DW_OP_call2) ? 2 : 4,
 			     die_offset, NULL);
       }
Index: gcc/testsuite/c-c++-common/Wint-in-bool-context.c
===================================================================
--- gcc/testsuite/c-c++-common/Wint-in-bool-context.c	(revision 0)
+++ gcc/testsuite/c-c++-common/Wint-in-bool-context.c	(working copy)
@@ -0,0 +1,19 @@
+/* PR c++/77434 */
+/* { dg-options "-Wint-in-bool-context" } */
+/* { dg-do compile } */
+
+int foo (int a, int b)
+{
+  if (a > 0 && a <= (b == 1) ? 1 : 2) /* { dg-warning "boolean context" } */
+    return 1;
+
+  if (a > 0 && a <= (b == 2) ? 1 : 1) /* { dg-bogus "boolean context" } */
+    return 2;
+
+  if (a > 0 && a <= (b == 3) ? 0 : 2) /* { dg-bogus "boolean context" } */
+    return 3;
+
+  for (a = 0; 1 << a; a++); /* { dg-warning "boolean context" } */
+
+  return 0;
+}