Patchwork C++ PATCH for c++/48015 (C++0x ICE with non-constant initializer for const int var in template)

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Submitter Jason Merrill
Date March 8, 2011, 5:25 a.m.
Message ID <4D75BDAD.9010401@redhat.com>
Download mbox | patch
Permalink /patch/85904/
State New
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Comments

Jason Merrill - March 8, 2011, 5:25 a.m.
constant_value_1 has been trying to pull out DECL_INITIAL for any 
variable with the proper type.  This can be problematic in templates, 
where DECL_INITIAL hasn't always been properly folded yet.  But since we 
try to reduce initializers to a constant when we process the 
declaration, we can just decide whether or not we want to use the 
initializer based on TREE_CONSTANT.

Tested x86_64-pc-linux-gnu, applying to trunk.
commit 9c7fa022068d56f4417aeea733e8bdf21c4a98e7
Author: Jason Merrill <jason@redhat.com>
Date:   Mon Mar 7 16:00:05 2011 -0500

    	PR c++/48015
    	* init.c (constant_value_1): Always require init to be TREE_CONSTANT.

Patch

diff --git a/gcc/cp/init.c b/gcc/cp/init.c
index e590118..56f66fa 100644
--- a/gcc/cp/init.c
+++ b/gcc/cp/init.c
@@ -1760,17 +1760,15 @@  constant_value_1 (tree decl, bool integral_p)
 	init = TREE_VALUE (init);
       if (!init
 	  || !TREE_TYPE (init)
-	  || uses_template_parms (init)
-	  || (integral_p
-	      ? false
-	      : (!TREE_CONSTANT (init)
-		 /* Do not return an aggregate constant (of which
-		    string literals are a special case), as we do not
-		    want to make inadvertent copies of such entities,
-		    and we must be sure that their addresses are the
-		    same everywhere.  */
-		 || TREE_CODE (init) == CONSTRUCTOR
-		 || TREE_CODE (init) == STRING_CST)))
+	  || !TREE_CONSTANT (init)
+	  || (!integral_p
+	      /* Do not return an aggregate constant (of which
+		 string literals are a special case), as we do not
+		 want to make inadvertent copies of such entities,
+		 and we must be sure that their addresses are the
+		 same everywhere.  */
+	      && (TREE_CODE (init) == CONSTRUCTOR
+		  || TREE_CODE (init) == STRING_CST)))
 	break;
       decl = unshare_expr (init);
     }
diff --git a/gcc/testsuite/g++.dg/cpp0x/regress/non-const1.C b/gcc/testsuite/g++.dg/cpp0x/regress/non-const1.C
new file mode 100644
index 0000000..7fc66a7
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/regress/non-const1.C
@@ -0,0 +1,9 @@ 
+// PR c++/48015
+// { dg-options -std=c++0x }
+
+template <typename T> T f(T);
+template <typename T> void g()
+{
+  int const c = f (1);
+  int i = c - 0;
+}