[C] Fix failing assertion with designated inits (#154120)

Incompatible pointer to integer conversion diagnostic checks would
trigger an assertion when the designated initializer is for an array of
unknown bounds.

Fixes #154046

Author: AaronBallman

clang/docs/ReleaseNotes.rst

@@ -193,6 +193,8 @@ Bug Fixes in This Version
   targets that treat ``_Float16``/``__fp16`` as native scalar types. Previously
   the warning was silently lost because the operands differed only by an implicit
   cast chain. (#GH149967).
+- Fixed a crash with incompatible pointer to integer conversions in designated
+  initializers involving string literals. (#GH154046)
 
 Bug Fixes to Compiler Builtins
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

clang/lib/Sema/SemaInit.cpp

@@ -3294,8 +3294,9 @@ InitListChecker::CheckDesignatedInitializer(const InitializedEntity &Entity,
     if (StringLiteral *SL = dyn_cast<StringLiteral>(SubExpr)) {
       // Get the length of the string.
       uint64_t StrLen = SL->getLength();
-      if (cast<ConstantArrayType>(AT)->getSize().ult(StrLen))
-        StrLen = cast<ConstantArrayType>(AT)->getZExtSize();
+      if (const auto *CAT = dyn_cast<ConstantArrayType>(AT);
+          CAT && CAT->getSize().ult(StrLen))
+        StrLen = CAT->getZExtSize();
       StructuredList->resizeInits(Context, StrLen);
 
       // Build a literal for each character in the string, and put them into
@@ -3317,8 +3318,9 @@ InitListChecker::CheckDesignatedInitializer(const InitializedEntity &Entity,
 
       // Get the length of the string.
       uint64_t StrLen = Str.size();
-      if (cast<ConstantArrayType>(AT)->getSize().ult(StrLen))
-        StrLen = cast<ConstantArrayType>(AT)->getZExtSize();
+      if (const auto *CAT = dyn_cast<ConstantArrayType>(AT);
+          CAT && CAT->getSize().ult(StrLen))
+        StrLen = CAT->getZExtSize();
       StructuredList->resizeInits(Context, StrLen);
 
       // Build a literal for each character in the string, and put them into

clang/test/Sema/designated-initializers.c

@@ -368,3 +368,10 @@ struct {
     .b = 0, // expected-warning {{initializer overrides prior initialization of this subobject}}
   },
 };
+
+void gh154046(void) {
+  (void)(const char[]) {
+    [0] = "", // expected-error {{incompatible pointer to integer conversion initializing 'const char' with an expression of type 'char[1]'}}
+    [1] = ""  // expected-error {{incompatible pointer to integer conversion initializing 'const char' with an expression of type 'char[1]'}}
+  }[1];
+}

clang/test/SemaObjC/exprs.m

@@ -36,3 +36,10 @@ void test_encode(void) {
   (void)@encode(Incomplete_ObjC_class*);
   (void)@encode(id);
 }
+
+void gh154046(void) {
+  (void)(const char[]) {
+    [0] = @encode(int),  // expected-error {{incompatible pointer to integer conversion initializing 'const char' with an expression of type 'char[2]'}}
+    [1] = @encode(float) // expected-error {{incompatible pointer to integer conversion initializing 'const char' with an expression of type 'char[2]'}}
+  }[1];
+}