From efe49da0ba74c2fa1efe212d9c91cbdb1680c06d Mon Sep 17 00:00:00 2001
From: Jason Merrill <jason@redhat.com>
Date: Fri, 1 Feb 2002 14:32:51 -0500
Subject: [PATCH] re PR c++/4872 (missed warning (no return) -- regression from
 2.95)

        PR c++/4872
        * decl.c (finish_function): Warn about a non-void function with
        no return statement and no abnormal exit.
        * cp-tree.h (struct cp_language_function): Add returns_abnormally.
        (current_function_returns_abnormally): New macro.
        * call.c (build_call): Set it.

From-SVN: r49407
---
 gcc/cp/ChangeLog                                 |  7 +++++++
 gcc/cp/call.c                                    |  3 +++
 gcc/cp/cp-tree.h                                 |  7 +++++++
 gcc/cp/decl.c                                    | 12 ++++++++++++
 gcc/testsuite/g++.dg/abi/empty4.C                |  2 +-
 gcc/testsuite/g++.dg/other/const2.C              |  2 +-
 gcc/testsuite/g++.dg/other/deprecated.C          |  4 ++--
 gcc/testsuite/g++.old-deja/g++.bob/inherit2.C    |  4 +++-
 gcc/testsuite/g++.old-deja/g++.bugs/900205_03.C  |  4 ++--
 gcc/testsuite/g++.old-deja/g++.jason/byval2.C    |  4 ++--
 gcc/testsuite/g++.old-deja/g++.law/operators17.C |  6 +++---
 gcc/testsuite/g++.old-deja/g++.mike/eh50.C       |  2 +-
 gcc/testsuite/g++.old-deja/g++.mike/eh51.C       |  2 +-
 gcc/testsuite/g++.old-deja/g++.mike/net20.C      |  1 +
 gcc/testsuite/g++.old-deja/g++.mike/net40.C      |  2 +-
 gcc/testsuite/g++.old-deja/g++.mike/net45.C      |  3 +--
 gcc/testsuite/g++.old-deja/g++.mike/p10511.C     |  2 +-
 gcc/testsuite/g++.old-deja/g++.mike/p11012.C     |  2 +-
 gcc/testsuite/g++.old-deja/g++.mike/p7325.C      |  1 +
 gcc/testsuite/g++.old-deja/g++.other/crash25.C   |  2 +-
 gcc/testsuite/g++.old-deja/g++.other/for1.C      |  2 ++
 gcc/testsuite/g++.old-deja/g++.other/init12.C    |  2 +-
 gcc/testsuite/g++.old-deja/g++.other/new.C       |  5 ++++-
 gcc/testsuite/g++.old-deja/g++.other/new4.C      |  1 +
 gcc/testsuite/g++.old-deja/g++.other/rtti1.C     |  6 +++---
 gcc/testsuite/g++.old-deja/g++.pt/spec1.C        |  2 +-
 26 files changed, 64 insertions(+), 26 deletions(-)

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index af18329d129..0bd68be0651 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,5 +1,12 @@
 2002-02-01  Jason Merrill  <jason@redhat.com>
 
+	PR c++/4872
+	* decl.c (finish_function): Warn about a non-void function with 
+	no return statement and no abnormal exit.
+	* cp-tree.h (struct cp_language_function): Add returns_abnormally.
+	(current_function_returns_abnormally): New macro.
+	* call.c (build_call): Set it.
+
 	* typeck.c (build_component_ref): Always complain about offsetof
 	constructs on non-PODs.  Only make it an error for members of
 	virtual bases.
diff --git a/gcc/cp/call.c b/gcc/cp/call.c
index cf6f0b42104..925bd067187 100644
--- a/gcc/cp/call.c
+++ b/gcc/cp/call.c
@@ -408,6 +408,9 @@ build_call (function, parms)
   nothrow = ((decl && TREE_NOTHROW (decl))
 	     || TYPE_NOTHROW_P (TREE_TYPE (TREE_TYPE (function))));
 
+  if (decl && TREE_THIS_VOLATILE (decl))
+    current_function_returns_abnormally = 1;
+
   if (decl && TREE_DEPRECATED (decl))
     warn_deprecated_use (decl);
 
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index f7cddacef7e..703720e9962 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -821,6 +821,7 @@ struct cp_language_function
 
   int returns_value;
   int returns_null;
+  int returns_abnormally;
   int in_function_try_handler;
   int x_expanding_p;
 
@@ -883,6 +884,12 @@ struct cp_language_function
 
 #define current_function_returns_null cp_function_chain->returns_null
 
+/* Set to 0 at beginning of a function definition, set to 1 if
+   a call to a noreturn function is seen.  */
+
+#define current_function_returns_abnormally \
+  cp_function_chain->returns_abnormally
+
 /* Non-zero if we should generate RTL for functions that we process.
    When this is zero, we just accumulate tree structure, without
    interacting with the back end.  */
diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index a5d9c64767c..097b562281d 100644
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -14247,6 +14247,18 @@ finish_function (flags)
   if (!processing_template_decl && calls_setjmp_p (fndecl))
     DECL_UNINLINABLE (fndecl) = 1;
 
+  /* Complain if there's just no return statement.  */
+  if (!processing_template_decl
+      && TREE_CODE (TREE_TYPE (fntype)) != VOID_TYPE
+      && !current_function_returns_value
+      && !DECL_NAME (DECL_RESULT (fndecl))
+      /* Don't complain if we abort or throw.  */
+      && !current_function_returns_abnormally
+      /* If we have -Wreturn-type, let flow complain.  Unless we're an
+	 inline function, as we might never be compiled separately.  */
+      && (!warn_return_type || DECL_INLINE (fndecl))
+    warning ("no return statement in function returning non-void");
+    
   /* Clear out memory we no longer need.  */
   free_after_parsing (cfun);
   /* Since we never call rest_of_compilation, we never clear
diff --git a/gcc/testsuite/g++.dg/abi/empty4.C b/gcc/testsuite/g++.dg/abi/empty4.C
index fe3d9a81a46..d20a55cf7fc 100644
--- a/gcc/testsuite/g++.dg/abi/empty4.C
+++ b/gcc/testsuite/g++.dg/abi/empty4.C
@@ -18,7 +18,7 @@ struct NonPod
 
   NonPod () {m = 0x12345678;}
   NonPod (long m_) {m = m_;}
-  NonPod &operator= (NonPod const &src) {now = m; m = src.m;}
+  NonPod &operator= (NonPod const &src) {now = m; m = src.m; return *this;}
   NonPod (NonPod const &src) {m = src.m;}
 };
 
diff --git a/gcc/testsuite/g++.dg/other/const2.C b/gcc/testsuite/g++.dg/other/const2.C
index 25778fa73bc..86dde1e4559 100644
--- a/gcc/testsuite/g++.dg/other/const2.C
+++ b/gcc/testsuite/g++.dg/other/const2.C
@@ -10,7 +10,7 @@ struct foo
 
   static const bar bars[];
 
-  int bad ()
+  void bad ()
   {
     this->*(bars[0].b) = 42; // { dg-bogus "read-only" "" }
   }
diff --git a/gcc/testsuite/g++.dg/other/deprecated.C b/gcc/testsuite/g++.dg/other/deprecated.C
index 40d9dba9c36..10560705031 100644
--- a/gcc/testsuite/g++.dg/other/deprecated.C
+++ b/gcc/testsuite/g++.dg/other/deprecated.C
@@ -13,10 +13,10 @@ INT1 should_be_unavailable; 		/* { dg-warning "`INT1' is deprecated" "" } */
 INT1a should_not_be_deprecated;
 
 INT1 f1(void) __attribute__ ((deprecated)); 
-INT1 f2(void) {}			/* { dg-warning "`INT1' is deprecated" "" } */
+INT1 f2(void) { return 0; }		/* { dg-warning "`INT1' is deprecated" "" } */
 
 INT2 f3(void) __attribute__ ((__deprecated__)); 
-INT2 f4(void) {}			/* { dg-warning "`INT2' is deprecated" "" } */
+INT2 f4(void) { return 0; }		/* { dg-warning "`INT2' is deprecated" "" } */
 int f5(INT2 x);				/* { dg-warning "`INT2' is deprecated" "" } */
 int f6(INT2 x) __attribute__ ((__deprecated__));
 
diff --git a/gcc/testsuite/g++.old-deja/g++.bob/inherit2.C b/gcc/testsuite/g++.old-deja/g++.bob/inherit2.C
index fe9e73b95fa..a7aa4fe0adf 100644
--- a/gcc/testsuite/g++.old-deja/g++.bob/inherit2.C
+++ b/gcc/testsuite/g++.old-deja/g++.bob/inherit2.C
@@ -1,11 +1,13 @@
 // Build don't link:
+#include <stdlib.h>
+
 class A {
 public:
   void z();
   A(void) {}
 private:
   A(const A &) { abort(); } // ERROR - 
-  const A& operator =(const A &) { abort(); } // WARNING - no return stmt XFAIL *-*-*
+  const A& operator =(const A &) { abort(); }
 };
 
 class B : public A {
diff --git a/gcc/testsuite/g++.old-deja/g++.bugs/900205_03.C b/gcc/testsuite/g++.old-deja/g++.bugs/900205_03.C
index a6249546d34..4c352c87ae4 100644
--- a/gcc/testsuite/g++.old-deja/g++.bugs/900205_03.C
+++ b/gcc/testsuite/g++.old-deja/g++.bugs/900205_03.C
@@ -25,10 +25,10 @@ struct00 global_function_1 () {
 struct struct0 {
 
   int struct0_member_function_0 () {
-  }					// ERROR - XFAIL
+  }					// ERROR - 
 
   struct0 struct0_member_function_1 () {
-  }					// ERROR - XFAIL
+  }					// ERROR - 
 };
 
 struct struct1 {
diff --git a/gcc/testsuite/g++.old-deja/g++.jason/byval2.C b/gcc/testsuite/g++.old-deja/g++.jason/byval2.C
index 490e625805d..62025813b32 100644
--- a/gcc/testsuite/g++.old-deja/g++.jason/byval2.C
+++ b/gcc/testsuite/g++.old-deja/g++.jason/byval2.C
@@ -13,8 +13,8 @@ public:
   void  operator -= (const Char   );
 };
 
-inline  Char  operator -  (const Char    a, const Char    b) {}
-inline  char  operator == (const Char    a, const char b) {}
+inline  Char  operator -  (const Char    a, const Char    b) { return Char(0); }
+inline  char  operator == (const Char    a, const char b) { return 0; }
 
 char mystrcmp(Char s[31], Char t[31])
 {
diff --git a/gcc/testsuite/g++.old-deja/g++.law/operators17.C b/gcc/testsuite/g++.old-deja/g++.law/operators17.C
index 9c1a03b5531..7674233e688 100644
--- a/gcc/testsuite/g++.old-deja/g++.law/operators17.C
+++ b/gcc/testsuite/g++.old-deja/g++.law/operators17.C
@@ -7,6 +7,6 @@
 // Subject:  4 bugs in g++ 2.3.3
 // Message-ID: <9304291053.AA00090@mencon>
 
-        struct A {
-                A& operator = (const A& a) {}// ERROR - XFAIL
-        };
+struct A {
+        A& operator = (const A& a) {}// WARNING - 
+};
diff --git a/gcc/testsuite/g++.old-deja/g++.mike/eh50.C b/gcc/testsuite/g++.old-deja/g++.mike/eh50.C
index 84ccaddb9a9..702bbda7eac 100644
--- a/gcc/testsuite/g++.old-deja/g++.mike/eh50.C
+++ b/gcc/testsuite/g++.old-deja/g++.mike/eh50.C
@@ -7,7 +7,7 @@ void my_unexpected() {
   throw 42;
 }
 
-template <class T> int foo(T) throw (int) { throw "Hi"; }
+template <class T> void foo(T) throw (int) { throw "Hi"; }
 
 main() {
   std::set_unexpected (my_unexpected);
diff --git a/gcc/testsuite/g++.old-deja/g++.mike/eh51.C b/gcc/testsuite/g++.old-deja/g++.mike/eh51.C
index 9ebeb4e8221..f1b90b42200 100644
--- a/gcc/testsuite/g++.old-deja/g++.mike/eh51.C
+++ b/gcc/testsuite/g++.old-deja/g++.mike/eh51.C
@@ -7,7 +7,7 @@ void my_unexpected() {
   throw 42;
 }
 
-template <class T> int foo(T) throw (T) { throw "Hi"; }
+template <class T> void foo(T) throw (T) { throw "Hi"; }
 
 main() {
   std::set_unexpected (my_unexpected);
diff --git a/gcc/testsuite/g++.old-deja/g++.mike/net20.C b/gcc/testsuite/g++.old-deja/g++.mike/net20.C
index 916ba434b37..731f6c149cc 100644
--- a/gcc/testsuite/g++.old-deja/g++.mike/net20.C
+++ b/gcc/testsuite/g++.old-deja/g++.mike/net20.C
@@ -8,4 +8,5 @@ struct X
 void (X::* fee ())()
 {
  lab: goto lab;
+ return 0;
 }
diff --git a/gcc/testsuite/g++.old-deja/g++.mike/net40.C b/gcc/testsuite/g++.old-deja/g++.mike/net40.C
index 10e16e685b7..db0df8a8678 100644
--- a/gcc/testsuite/g++.old-deja/g++.mike/net40.C
+++ b/gcc/testsuite/g++.old-deja/g++.mike/net40.C
@@ -1,5 +1,5 @@
 #include <stddef.h>
-extern "C" void abort();
+#include <stdlib.h>
 
 class toto {
 public:
diff --git a/gcc/testsuite/g++.old-deja/g++.mike/net45.C b/gcc/testsuite/g++.old-deja/g++.mike/net45.C
index 388af8fe82f..fca48e9c295 100644
--- a/gcc/testsuite/g++.old-deja/g++.mike/net45.C
+++ b/gcc/testsuite/g++.old-deja/g++.mike/net45.C
@@ -12,8 +12,7 @@ struct myint {
   }
   myint(const myint& mi) {
   }
-  myint& operator=(const myint& mi) {
-  }
+  myint& operator=(const myint& mi) { return *this; }
 };
 
 extern pair<const myint, myint> a;
diff --git a/gcc/testsuite/g++.old-deja/g++.mike/p10511.C b/gcc/testsuite/g++.old-deja/g++.mike/p10511.C
index b92b4f7d7fd..abe12e40d88 100644
--- a/gcc/testsuite/g++.old-deja/g++.mike/p10511.C
+++ b/gcc/testsuite/g++.old-deja/g++.mike/p10511.C
@@ -8,7 +8,7 @@ public:
 
 class C {
 public:
-  bool f (S::E()) { }
+  bool f (S::E()) { return true; }
   virtual void foo();
 };
 
diff --git a/gcc/testsuite/g++.old-deja/g++.mike/p11012.C b/gcc/testsuite/g++.old-deja/g++.mike/p11012.C
index aca77d42607..407c83a8fcb 100644
--- a/gcc/testsuite/g++.old-deja/g++.mike/p11012.C
+++ b/gcc/testsuite/g++.old-deja/g++.mike/p11012.C
@@ -4,7 +4,7 @@
 
 class Foo {
 public:
-  int f(){}
+  int f(){ return 0; }
 };
 
 void foo() {
diff --git a/gcc/testsuite/g++.old-deja/g++.mike/p7325.C b/gcc/testsuite/g++.old-deja/g++.mike/p7325.C
index e6d76f5321e..e481ccde0a6 100644
--- a/gcc/testsuite/g++.old-deja/g++.mike/p7325.C
+++ b/gcc/testsuite/g++.old-deja/g++.mike/p7325.C
@@ -23,6 +23,7 @@ struct A {
       if (match_arg != &o)
 	fail = 1;
     match_arg = &o;
+    return *this;
   }
 };
 
diff --git a/gcc/testsuite/g++.old-deja/g++.other/crash25.C b/gcc/testsuite/g++.old-deja/g++.other/crash25.C
index 2f471fb866f..0c39be8b0bd 100644
--- a/gcc/testsuite/g++.old-deja/g++.other/crash25.C
+++ b/gcc/testsuite/g++.old-deja/g++.other/crash25.C
@@ -9,7 +9,7 @@ public:
 
 X::x()
 {				// ERROR - 
-}
+} // WARNING - no return
 
 X::~x()
 {				// ERROR - 
diff --git a/gcc/testsuite/g++.old-deja/g++.other/for1.C b/gcc/testsuite/g++.old-deja/g++.other/for1.C
index 31cd741a366..e737a41fa2a 100644
--- a/gcc/testsuite/g++.old-deja/g++.other/for1.C
+++ b/gcc/testsuite/g++.old-deja/g++.other/for1.C
@@ -7,6 +7,7 @@ struct S {
   int operator()(int)
     {
       i = 1;
+      return i;
     }
 
   typedef int I;
@@ -24,6 +25,7 @@ struct T {
   int operator()(int)
     {
       j = 1;
+      return j;
     }
 
   void f() {
diff --git a/gcc/testsuite/g++.old-deja/g++.other/init12.C b/gcc/testsuite/g++.old-deja/g++.other/init12.C
index ee0a029253a..9e4a4360157 100644
--- a/gcc/testsuite/g++.old-deja/g++.other/init12.C
+++ b/gcc/testsuite/g++.old-deja/g++.other/init12.C
@@ -11,7 +11,7 @@ struct S
 
 struct T
 {
-  static int f() {}
+  static int f() { return 0; }
 };
 
 static const S s = { &T::f };
diff --git a/gcc/testsuite/g++.old-deja/g++.other/new.C b/gcc/testsuite/g++.old-deja/g++.other/new.C
index e2839578d15..45187629a57 100644
--- a/gcc/testsuite/g++.old-deja/g++.other/new.C
+++ b/gcc/testsuite/g++.old-deja/g++.other/new.C
@@ -1,13 +1,16 @@
 // Build don't link:
 
-typedef __SIZE_TYPE__ size_t;
+#include <new>
+
 inline void *
 operator new(size_t alloc_sz, const char *fname, unsigned lineno)
 {
+  return ::operator new (alloc_sz);
 }
 inline void *
 operator new[](size_t alloc_sz, const char *fname, unsigned lineno) 
 {
+  return ::operator new[] (alloc_sz);
 }
 inline void
 operator delete(void *ptr, const char *fname, unsigned lineno) 
diff --git a/gcc/testsuite/g++.old-deja/g++.other/new4.C b/gcc/testsuite/g++.old-deja/g++.other/new4.C
index b9931b1caa5..2eb0954e741 100644
--- a/gcc/testsuite/g++.old-deja/g++.other/new4.C
+++ b/gcc/testsuite/g++.old-deja/g++.other/new4.C
@@ -6,5 +6,6 @@ struct S {
 
   virtual int f() {
     new S[+f()];
+    return 0;
   }
 };
diff --git a/gcc/testsuite/g++.old-deja/g++.other/rtti1.C b/gcc/testsuite/g++.old-deja/g++.other/rtti1.C
index 7377e156dba..603c7d2311b 100644
--- a/gcc/testsuite/g++.old-deja/g++.other/rtti1.C
+++ b/gcc/testsuite/g++.old-deja/g++.other/rtti1.C
@@ -39,15 +39,15 @@ class XX {
 public:
   int xxi;
   float xxf;
-  int xxf1 () {};
-  int xxf2 (int k) {};
+  int xxf1 () { return 0; };
+  int xxf2 (int k) { return 0; };
 };
 
 class YY {
 public:
   int yyi;
   double yyd;
-  int yyf1 (float f) {};
+  int yyf1 (float f) { return 0; };
   double yyf2 () {return yyd;};
 };
 
diff --git a/gcc/testsuite/g++.old-deja/g++.pt/spec1.C b/gcc/testsuite/g++.old-deja/g++.pt/spec1.C
index 7467293e145..ab18ff81c81 100644
--- a/gcc/testsuite/g++.old-deja/g++.pt/spec1.C
+++ b/gcc/testsuite/g++.old-deja/g++.pt/spec1.C
@@ -13,7 +13,7 @@ public:
 };
 
 struct Operation {
-  double eval(double) {}
+  double eval(double) { return 0; }
 };
 
 int main() {