PR c/21342

	* c-decl.c (pushdecl): When there is a declaration in the current
	scope and the declarations are external linkage, check for
	compatibility with the type in the external scope and update the
	type in the external scope with the composite type information.
	Do not form a composite type of the new type and the visible type
	if they are incompatible.

testsuite:
	* gcc.dg/redecl-11.c, gcc.dg/redecl-12.c, gcc.dg/redecl-13.c,
	gcc.dg/redecl-14.c, gcc.dg/redecl-15.c: New tests.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@99510 138bc75d-0d04-0410-961f-82ee72b054a4

8 files changed, 131 insertions, 3 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 82d7ba0629d..ffdd2bbff2a 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,13 @@
+2005-05-10  Joseph S. Myers  <joseph@codesourcery.com>
+
+	PR c/21342
+	* c-decl.c (pushdecl): When there is a declaration in the current
+	scope and the declarations are external linkage, check for
+	compatibility with the type in the external scope and update the
+	type in the external scope with the composite type information.
+	Do not form a composite type of the new type and the visible type
+	if they are incompatible.
+
 2005-05-10  Nathan Sidwell  <nathan@codesourcery.com>
 
 	* crtstuff.c: Revert part of 2005-05-08 Change.
diff --git a/gcc/c-decl.c b/gcc/c-decl.c
index e7ac0d3690d..0ca4500021e 100644
--- a/gcc/c-decl.c
+++ b/gcc/c-decl.c
@@ -2029,11 +2029,52 @@ pushdecl (tree x)
   b = I_SYMBOL_BINDING (name);
   if (b && B_IN_SCOPE (b, scope))
     {
+      struct c_binding *b_ext, *b_use;
+      tree type = TREE_TYPE (x);
+      tree visdecl = b->decl;
+      tree vistype = TREE_TYPE (visdecl);
       if (TREE_CODE (TREE_TYPE (x)) == ARRAY_TYPE
 	  && COMPLETE_TYPE_P (TREE_TYPE (x)))
 	b->inner_comp = false;
-      if (duplicate_decls (x, b->decl))
-	return b->decl;
+      b_use = b;
+      b_ext = b;
+      /* If this is an external linkage declaration, we should check
+	 for compatibility with the type in the external scope before
+	 setting the type at this scope based on the visible
+	 information only.  */
+      if (TREE_PUBLIC (x) && TREE_PUBLIC (visdecl))
+	{
+	  while (b_ext && !B_IN_EXTERNAL_SCOPE (b_ext))
+	    b_ext = b_ext->shadowed;
+	  if (b_ext)
+	    {
+	      b_use = b_ext;
+	      if (b_use->type)
+		TREE_TYPE (b_use->decl) = b_use->type;
+	    }
+	}
+      if (duplicate_decls (x, b_use->decl))
+	{
+	  if (b_use != b)
+	    {
+	      /* Save the updated type in the external scope and
+		 restore the proper type for this scope.  */
+	      tree thistype;
+	      if (comptypes (vistype, type))
+		thistype = composite_type (vistype, type);
+	      else
+		thistype = TREE_TYPE (b_use->decl);
+	      b_use->type = TREE_TYPE (b_use->decl);
+	      if (TREE_CODE (b_use->decl) == FUNCTION_DECL
+		  && DECL_BUILT_IN (b_use->decl))
+		thistype
+		  = build_type_attribute_variant (thistype,
+						  TYPE_ATTRIBUTES
+						  (b_use->type));
+	      TREE_TYPE (b_use->decl) = thistype;
+	    }
+	  return b_use->decl;
+	}
       else
 	goto skip_external_and_shadow_checks;
     }
@@ -2120,7 +2161,15 @@ pushdecl (tree x)
 	  && duplicate_decls (x, b->decl))
 	{
 	  tree thistype;
-	  thistype = (vistype ? composite_type (vistype, type) : type);
+	  if (vistype)
+	    {
+	      if (comptypes (vistype, type))
+		thistype = composite_type (vistype, type);
+	      else
+		thistype = TREE_TYPE (b->decl);
+	    }
+	  else
+	    thistype = type;
 	  b->type = TREE_TYPE (b->decl);
 	  if (TREE_CODE (b->decl) == FUNCTION_DECL && DECL_BUILT_IN (b->decl))
 	    thistype
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 55605df8f03..7dd2e1970d9 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2005-05-10  Joseph S. Myers  <joseph@codesourcery.com>
+
+	PR c/21342
+	* gcc.dg/redecl-11.c, gcc.dg/redecl-12.c, gcc.dg/redecl-13.c,
+	gcc.dg/redecl-14.c, gcc.dg/redecl-15.c: New tests.
+
 2005-05-10  Ben Elliston  <bje@au.ibm.com>
 
 	PR debug/16676
diff --git a/gcc/testsuite/gcc.dg/redecl-11.c b/gcc/testsuite/gcc.dg/redecl-11.c
new file mode 100644
index 00000000000..a0554d9476d
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/redecl-11.c
@@ -0,0 +1,9 @@
+/* Some incompatible external linkage declarations were not diagnosed.
+   Bug 21342.  */
+/* Origin: Joseph Myers <joseph@codesourcery.com> */
+/* { dg-do compile } */
+/* { dg-options "" } */
+
+int f(int (*)[]);
+void g() { int f(int (*)[2]); } /* { dg-error "error: previous declaration of 'f' was here" } */
+int f(int (*)[3]); /* { dg-error "error: conflicting types for 'f'" } */
diff --git a/gcc/testsuite/gcc.dg/redecl-12.c b/gcc/testsuite/gcc.dg/redecl-12.c
new file mode 100644
index 00000000000..cb1501d30ac
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/redecl-12.c
@@ -0,0 +1,9 @@
+/* Some incompatible external linkage declarations were not diagnosed.
+   Bug 21342.  */
+/* Origin: Joseph Myers <joseph@codesourcery.com> */
+/* { dg-do compile } */
+/* { dg-options "" } */
+
+extern int a[];
+void f(void) { extern int a[]; extern int a[10]; } /* { dg-error "error: previous declaration of 'a' was here" } */
+extern int a[5]; /* { dg-error "error: conflicting types for 'a'" } */
diff --git a/gcc/testsuite/gcc.dg/redecl-13.c b/gcc/testsuite/gcc.dg/redecl-13.c
new file mode 100644
index 00000000000..54be4dbc2ba
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/redecl-13.c
@@ -0,0 +1,9 @@
+/* Some incompatible external linkage declarations were not diagnosed.
+   Bug 21342.  */
+/* Origin: Joseph Myers <joseph@codesourcery.com> */
+/* { dg-do compile } */
+/* { dg-options "" } */
+
+extern int a[];
+void f(void) { extern int a[10]; } /* { dg-error "error: previous declaration of 'a' was here" } */
+extern int a[5]; /* { dg-error "error: conflicting types for 'a'" } */
diff --git a/gcc/testsuite/gcc.dg/redecl-14.c b/gcc/testsuite/gcc.dg/redecl-14.c
new file mode 100644
index 00000000000..ed196106361
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/redecl-14.c
@@ -0,0 +1,22 @@
+/* Some incompatible external linkage declarations were not diagnosed.
+   Bug 21342.  Test type in inner scope is correct.  */
+/* Origin: Joseph Myers <joseph@codesourcery.com> */
+/* { dg-do compile } */
+/* { dg-options "" } */
+
+typedef int IA[];
+typedef int IA5[5];
+typedef IA *IAP;
+typedef IA5 *IA5P;
+extern IAP a[];
+void
+f (void)
+{
+  {
+    extern IA5P a[];
+    sizeof (*a[0]);
+  }
+  extern IAP a[];
+  extern IAP a[5];
+  sizeof (*a[0]); /* { dg-error "error: invalid application of 'sizeof' to incomplete type 'IA'" } */
+}
diff --git a/gcc/testsuite/gcc.dg/redecl-15.c b/gcc/testsuite/gcc.dg/redecl-15.c
new file mode 100644
index 00000000000..c4ac76cc8cf
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/redecl-15.c
@@ -0,0 +1,14 @@
+/* Test for ICE with redeclaration in inner scope which is accepted
+   despite incompatible type.  */
+/* Origin: Joseph Myers <joseph@codesourcery.com> */
+/* { dg-do compile } */
+/* { dg-options "" } */
+
+void
+f (void)
+{
+  g(); /* { dg-warning "warning: previous implicit declaration of 'g' was here" } */
+  {
+    void g(); /* { dg-warning "warning: conflicting types for 'g'" } */
+  }
+}