Implementing C99 partial re-initialization behavior (DR-253)

Based on previous discussion on the mailing list, clang currently lacks support
for C99 partial re-initialization behavior:
Reference: http://lists.cs.uiuc.edu/pipermail/cfe-dev/2013-April/029188.html
Reference: http://www.open-std.org/jtc1/sc22/wg14/www/docs/dr_253.htm

This patch attempts to fix this problem.

Given the following code snippet,

struct P1 { char x[6]; };
struct LP1 { struct P1 p1; };

struct LP1 l = { .p1 = { "foo" }, .p1.x[2] = 'x' };
// this example is adapted from the example for "struct fred x[]" in DR-253;
// currently clang produces in l: { "\0\0x" },
//   whereas gcc 4.8 produces { "fox" };
// with this fix, clang will also produce: { "fox" };


Differential Review: http://reviews.llvm.org/D5789

llvm-svn: 239446

1 files changed, 17 insertions, 7 deletions

diff --git a/clang/test/Sema/designated-initializers.c b/clang/test/Sema/designated-initializers.c
index 6630da67c5b..a4582deb171 100644
--- a/clang/test/Sema/designated-initializers.c
+++ b/clang/test/Sema/designated-initializers.c
@@ -45,8 +45,8 @@ struct point array[10] = {
 
 struct point array2[10] = {
   [10].x = 2.0, // expected-error{{array designator index (10) exceeds array bounds (10)}}
-  [4 ... 5].y = 2.0,
-  [4 ... 6] = { .x = 3, .y = 4.0 }
+  [4 ... 5].y = 2.0, // expected-note 2 {{previous initialization is here}}
+  [4 ... 6] = { .x = 3, .y = 4.0 }  // expected-warning 2 {{subobject initialization overrides initialization of other fields within its enclosing subobject}}
 };
 
 struct point array3[10] = {
@@ -129,11 +129,11 @@ int get8() { ++counter; return 8; }
 
 void test() {
   struct X xs[] = { 
-    [0] = (struct X){1, 2}, // expected-note{{previous initialization is here}}
+    [0] = (struct X){1, 2}, // expected-note 2 {{previous initialization is here}}
     [0].c = 3,  // expected-warning{{subobject initialization overrides initialization of other fields within its enclosing subobject}}
     (struct X) {4, 5, 6}, // expected-note{{previous initialization is here}}
     [1].b = get8(), // expected-warning{{subobject initialization overrides initialization of other fields within its enclosing subobject}}
-    [0].b = 8
+    [0].b = 8   // expected-warning{{subobject initialization overrides initialization of other fields within its enclosing subobject}}
   };
 }
 
@@ -332,12 +332,22 @@ struct overwrite_string_struct {
   int M;
 } overwrite_string[] = {
   { { "foo" }, 1 }, // expected-note {{previous initialization is here}}
-  [0].L[2] = 'x' // expected-warning{{initializer overrides prior initialization of this subobject}}
+  [0].L[2] = 'x' // expected-warning{{subobject initialization overrides initialization of other fields}}
 };
 struct overwrite_string_struct2 {
   char L[6];
   int M;
 } overwrite_string2[] = {
-    { { "foo" }, 1 },
-    [0].L[4] = 'x' // no-warning
+    { { "foo" }, 1 }, // expected-note{{previous initialization is here}}
+    [0].L[4] = 'x' // expected-warning{{subobject initialization overrides initialization of other fields}}
   };
+struct overwrite_string_struct
+overwrite_string3[] = {
+  "foo", 1,           // expected-note{{previous initialization is here}}
+  [0].L[4] = 'x'  // expected-warning{{subobject initialization overrides initialization of other fields}}
+};
+struct overwrite_string_struct
+overwrite_string4[] = {
+  { { 'f', 'o', 'o' }, 1 },
+  [0].L[4] = 'x' // no-warning
+};