Improve diagnostics when we fail to convert from a source type to a

destination type for initialization, assignment, parameter-passing,
etc. The main issue fixed here is that we used rather confusing
wording for diagnostics such as

t.c:2:9: warning: initializing 'char const [2]' discards qualifiers,
      expected 'char *' [-pedantic]
  char *name = __func__;
        ^      ~~~~~~~~

We're not initializing a 'char const [2]', we're initializing a 'char
*' with an expression of type 'char const [2]'. Similar problems
existed for other diagnostics in this area, so I've normalized them all
with more precise descriptive text to say what we're
initializing/converting/assigning/etc. from and to. The warning for
the code above is now:

t.c:2:9: warning: initializing 'char *' from an expression of type
      'char const [2]' discards qualifiers [-pedantic]
  char *name = __func__;
        ^      ~~~~~~~~

Fixes <rdar://problem/7447179>.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@100832 91177308-0d34-0410-b5e6-96231b3b80d8

70 files changed, 254 insertions, 198 deletions

diff --git a/include/clang/Basic/DiagnosticSemaKinds.td b/include/clang/Basic/DiagnosticSemaKinds.td
index e2d8d6fa77..27632f171f 100644
--- a/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/include/clang/Basic/DiagnosticSemaKinds.td
@@ -2229,44 +2229,81 @@ def warn_value_always_zero : Warning<
 // In most of these diagnostics the %2 is a value from the
 // Sema::AssignmentAction enumeration
 def err_typecheck_convert_incompatible : Error<
-  "incompatible type %select{assigning|passing|returning|converting|initializing|sending|casting}2"
-  " %1, expected %0">;
+  "%select{assigning to|passing|returning|converting|initializing|sending|casting}2"
+  " %0 "
+  "%select{from incompatible type|to parameter of incompatible type|"
+  "from a function with incompatible result type|to incompatible type|"
+  "from an expression of incompatible type|to parameter of incompatible type|"
+  "to incompatible type}2 %1">;
 def warn_incompatible_qualified_id : Warning<
-  "incompatible type %select{assigning|passing|returning|converting|initializing|sending|casting}2"
-  " %1, expected %0">;
+  "%select{assigning to|passing|returning|converting|initializing|sending|casting}2"
+  " %0 "
+  "%select{from incompatible type|to parameter of incompatible type|"
+  "from a function with incompatible result type|to incompatible type|"
+  "from an expression of incompatible type|to parameter of incompatible type|"
+  "to incompatible type}2 %1">;
 def ext_typecheck_convert_pointer_int : ExtWarn<
   "incompatible pointer to integer conversion "
-  "%select{assigning|passing|returning|converting|initializing|sending|casting}2 %1, expected %0">;
+  "%select{assigning to|passing|returning|converting|initializing|sending|casting}2"
+  " %0 "
+  "%select{from|to parameter of type|from a function with result type|to type|"
+  "from an expression of type|to parameter of type|to type}2 %1">;
 def ext_typecheck_convert_int_pointer : ExtWarn<
   "incompatible integer to pointer conversion "
-  "%select{assigning|passing|returning|converting|initializing|sending|casting}2 %1, expected %0">;
+  "%select{assigning to|passing|returning|converting|initializing|sending|casting}2"
+  " %0 "
+  "%select{from|to parameter of type|from a function with result type|to type|"
+  "from an expression of type|to parameter of type|to type}2 %1">;
 def ext_typecheck_convert_pointer_void_func : Extension<
-  "%select{assigning|passing|returning|converting|initializing|sending|casting}2"
-  " %1 converts between void* and function pointer, expected %0">;
+  "%select{assigning to|passing|returning|converting|initializing|sending|casting}2"
+  " %0 "
+  "%select{from|to parameter of type|from a function with result type|to type|"
+  "from an expression of type|to parameter of type|to type}2 %1 "
+  "converts between void pointer and function pointer">;
 def ext_typecheck_convert_incompatible_pointer_sign : ExtWarn<
- "pointer types point to integer types with different sign "
- "%select{assigning|passing|returning|converting|initializing|sending|casting}2 %1, expected %0">,
+  "%select{assigning to|passing|returning|converting|initializing|sending|casting}2"
+  " %0 "
+  "%select{from|to parameter of type|from a function with result type|to type|"
+  "from an expression of type|to parameter of type|to type}2 %1 "
+  "converts between pointers to integer types with different sign">,
   InGroup<DiagGroup<"pointer-sign">>;
 def ext_typecheck_convert_incompatible_pointer : ExtWarn<
   "incompatible pointer types "
-  "%select{assigning|passing|returning|converting|initializing|sending|casting}2 %1, expected %0">;
+  "%select{assigning to|passing|returning|converting|initializing|sending|casting}2"
+  " %0 "
+  "%select{from|to parameter of type|from a function with result type|to type|"
+  "from an expression of type|to parameter of type|to type}2 %1">;
 def ext_typecheck_convert_discards_qualifiers : ExtWarn<
-  "%select{assigning|passing|returning|converting|initializing|sending|casting}2"
-  " %1 discards qualifiers, expected %0">;
+  "%select{assigning to|passing|returning|converting|initializing|sending|casting}2"
+  " %0 "
+  "%select{from|to parameter of type|from a function with result type|to type|"
+  "from an expression of type|to parameter of type|to type}2 %1 discards "
+  "qualifiers">;
 def ext_nested_pointer_qualifier_mismatch : ExtWarn<
-  "%select{assigning|passing|returning|converting|initializing|sending|casting}2,"
-  " %0 and %1 have different qualifiers in nested pointer types">;
+  "%select{assigning to|passing|returning|converting|initializing|sending|casting}2"
+  " %0 "
+  "%select{from|to parameter of type|from a function with result type|to type|"
+  "from an expression of type|to parameter of type|to type}2 %1 discards "
+  "qualifiers in nested pointer types">;
 def warn_incompatible_vectors : Warning<
-  "incompatible vector types %select{assigning|passing|returning|converting|initializing|sending|casting}2"
-  " %1, expected %0">,
+  "incompatible vector types "
+  "%select{assigning to|passing|returning|converting|initializing|sending|casting}2"
+  " %0 "
+  "%select{from|to parameter of type|from a function with result type|to type|"
+  "from an expression of type|to parameter of type|to type}2 %1">,
   InGroup<VectorConversions>, DefaultIgnore;
 def err_int_to_block_pointer : Error<
-  "invalid conversion "
-  "%select{assigning|passing|returning|converting|initializing|sending|casting}2"
-  " integer %1, expected block pointer %0">;
+  "invalid block pointer conversion "
+  "%select{assigning to|passing|returning|converting|initializing|sending|casting}2"
+  " %0 "
+  "%select{from|to parameter of type|from a function with result type|to type|"
+  "from an expression of type|to parameter of type|to type}2 %1">;
 def err_typecheck_convert_incompatible_block_pointer : Error<
   "incompatible block pointer types "
-  "%select{assigning|passing|returning|converting|initializing|sending|casting}2 %1, expected %0">;
+  "%select{assigning to|passing|returning|converting|initializing|sending|casting}2"
+  " %0 "
+  "%select{from|to parameter of type|from a function with result type|to type|"
+  "from an expression of type|to parameter of type|to type}2 %1">;
   
 def err_typecheck_convert_ambiguous : Error<
   "ambiguity in initializing value of type %0 with initializer of type %1">;
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index da0c0a0499..654b220499 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -7201,7 +7201,27 @@ bool Sema::DiagnoseAssignmentResult(AssignConvertType ConvTy,
     break;
   }
 
-  Diag(Loc, DiagKind) << DstType << SrcType << Action
+  QualType FirstType, SecondType;
+  switch (Action) {
+  case AA_Assigning:
+  case AA_Initializing:
+    // The destination type comes first.
+    FirstType = DstType;
+    SecondType = SrcType;
+    break;
+      
+  case AA_Returning:
+  case AA_Passing:
+  case AA_Converting:
+  case AA_Sending:
+  case AA_Casting:
+    // The source type comes first.
+    FirstType = SrcType;
+    SecondType = DstType;
+    break;
+  }
+  
+  Diag(Loc, DiagKind) << FirstType << SecondType << Action
     << SrcExpr->getSourceRange() << Hint;
   return isInvalid;
 }
diff --git a/test/Analysis/null-deref-ps.c b/test/Analysis/null-deref-ps.c
index 5376ca0eb3..5a1049c7d7 100644
--- a/test/Analysis/null-deref-ps.c
+++ b/test/Analysis/null-deref-ps.c
@@ -62,8 +62,8 @@ int f4(int *p) {
 
 int f4_b() {
   short array[2];
-  uintptr_t x = array; // expected-warning{{incompatible pointer to integer conversion initializing}}
-  short *p = x; // expected-warning{{incompatible integer to pointer conversion initializing}}
+  uintptr_t x = array; // expected-warning{{incompatible pointer to integer conversion}}
+  short *p = x; // expected-warning{{incompatible integer to pointer conversion}}
   
   // The following branch should be infeasible.
   if (!(p = &array[0])) {
diff --git a/test/Analysis/override-werror.c b/test/Analysis/override-werror.c
index 522b9dcb94..f4854bb819 100644
--- a/test/Analysis/override-werror.c
+++ b/test/Analysis/override-werror.c
@@ -6,7 +6,7 @@
 // analyzer results.
 
 char* f(int *p) { 
-  return p; // expected-warning{{incompatible pointer types returning 'int *', expected 'char *'}}
+  return p; // expected-warning{{incompatible pointer types}}
 }
 
 void g(int *p) {
diff --git a/test/CXX/except/except.handle/p16.cpp b/test/CXX/except/except.handle/p16.cpp
index 87972f5985..4950a2f6aa 100644
--- a/test/CXX/except/except.handle/p16.cpp
+++ b/test/CXX/except/except.handle/p16.cpp
@@ -11,12 +11,12 @@ class X {
 public:
   X(const X<T> &) {
     int *ip = 0;
-    ptr = ip; // expected-error{{incompatible type assigning 'int *', expected 'float *'}}
+    ptr = ip; // expected-error{{assigning to 'float *' from incompatible type 'int *'}}
   }
 
   ~X() {
     float *fp = 0;
-    ptr = fp; // expected-error{{incompatible type assigning 'float *', expected 'int *'}}
+    ptr = fp; // expected-error{{assigning to 'int *' from incompatible type 'float *'}}
   }
 };
 
diff --git a/test/FixIt/fixit-objc.m b/test/FixIt/fixit-objc.m
index 665ac74441..072d50a69b 100644
--- a/test/FixIt/fixit-objc.m
+++ b/test/FixIt/fixit-objc.m
@@ -27,7 +27,7 @@ void h(id a);
 void f(Test *t) {
   NSString *a = "Foo";
   id b = "Foo";
-  A* c = "Foo"; // expected-warning {{incompatible pointer types initializing 'char [4]', expected 'A *'}}
+  A* c = "Foo"; // expected-warning {{incompatible pointer types initializing 'A *' from an expression of type 'char [4]'}}
   g("Foo");
   h("Foo");
   h(("Foo"));
diff --git a/test/PCH/functions.c b/test/PCH/functions.c
index eb8579ab2e..5d7849e129 100644
--- a/test/PCH/functions.c
+++ b/test/PCH/functions.c
@@ -15,7 +15,7 @@ float *test_f1(int val, double x, double y) {
 }
 
 void test_g0(int *x, float * y) {
-  g0(y); // expected-warning{{incompatible pointer types passing 'float *', expected 'int *'}}
+  g0(y); // expected-warning{{incompatible pointer types passing 'float *' to parameter of type 'int *'}}
   g0(x); 
 }
 
diff --git a/test/PCH/types.c b/test/PCH/types.c
index 1ebc01be6a..5ca6a6893f 100644
--- a/test/PCH/types.c
+++ b/test/PCH/types.c
@@ -66,7 +66,7 @@ int_ptr_ptr ipp = &int_value_ptr;
 // TYPE_TYPEOF_EXPR
 typeof_17 *t17 = &int_value;
 struct S { int x, y; };
-typeof_17 t17_2 = (struct S){1, 2}; // expected-error{{incompatible type initializing}}
+typeof_17 t17_2 = (struct S){1, 2}; // expected-error{{initializing 'typeof_17' (aka 'int') from an expression of incompatible type 'struct S'}}
 
 // TYPE_TYPEOF
 int_ptr_ptr2 ipp2 = &int_value_ptr;
diff --git a/test/Parser/altivec.c b/test/Parser/altivec.c
index c2a32cfa39..6c4601abe9 100644
--- a/test/Parser/altivec.c
+++ b/test/Parser/altivec.c
@@ -81,8 +81,8 @@ void f() {
   gccvector unsigned int gv = v;
   gccvector int gvi = (gccvector int)v;
   __attribute__((vector_size(8))) unsigned int gv8;
-  gv8 = gccv;     // expected-error {{incompatible type assigning '__attribute__((__vector_size__(4 * sizeof(unsigned int)))) unsigned int', expected '__attribute__((__vector_size__(2 * sizeof(unsigned int)))) unsigned int'}}
-  av = gv8;       // expected-error {{incompatible type assigning '__attribute__((__vector_size__(2 * sizeof(unsigned int)))) unsigned int', expected '__vector unsigned int'}}
+  gv8 = gccv;     // expected-error {{assigning to '__attribute__((__vector_size__(2 * sizeof(unsigned int)))) unsigned int' from incompatible type '__attribute__((__vector_size__(4 * sizeof(unsigned int)))) unsigned int'}}
+  av = gv8;       // expected-error {{assigning to '__vector unsigned int' from incompatible type '__attribute__((__vector_size__(2 * sizeof(unsigned int)))) unsigned int'}}
 
   v = gccv;
   __vector unsigned int tv = gccv;
diff --git a/test/Parser/builtin_types_compatible.c b/test/Parser/builtin_types_compatible.c
index 325615c7ee..ac81e7b08d 100644
--- a/test/Parser/builtin_types_compatible.c
+++ b/test/Parser/builtin_types_compatible.c
@@ -35,7 +35,7 @@ static void test()
   struct xx { int a; } x, y;
   
   c = __builtin_choose_expr(a+3-7, b, x); // expected-error{{'__builtin_choose_expr' requires a constant expression}}
-  c = __builtin_choose_expr(0, b, x); // expected-error{{incompatible type assigning 'struct xx', expected 'int'}}
+  c = __builtin_choose_expr(0, b, x); // expected-error{{assigning to 'int' from incompatible type 'struct xx'}}
   c = __builtin_choose_expr(5+3-7, b, x);
   y = __builtin_choose_expr(4+3-7, b, x);
 
diff --git a/test/Parser/cxx-altivec.cpp b/test/Parser/cxx-altivec.cpp
index 3610c0e049..13a270b8e6 100644
--- a/test/Parser/cxx-altivec.cpp
+++ b/test/Parser/cxx-altivec.cpp
@@ -81,8 +81,8 @@ void f() {
   gccvector unsigned int gv = v;
   gccvector int gvi = (gccvector int)v;
   __attribute__((vector_size(8))) unsigned int gv8;
-  gv8 = gccv;     // expected-error {{incompatible type assigning '__attribute__((__vector_size__(4 * sizeof(unsigned int)))) unsigned int', expected '__attribute__((__vector_size__(2 * sizeof(unsigned int)))) unsigned int'}}
-  av = gv8;       // expected-error {{incompatible type assigning '__attribute__((__vector_size__(2 * sizeof(unsigned int)))) unsigned int', expected '__vector unsigned int'}}
+  gv8 = gccv;     // expected-error {{assigning to '__attribute__((__vector_size__(2 * sizeof(unsigned int)))) unsigned int' from incompatible type '__attribute__((__vector_size__(4 * sizeof(unsigned int)))) unsigned int'}}
+  av = gv8;       // expected-error {{assigning to '__vector unsigned int' from incompatible type '__attribute__((__vector_size__(2 * sizeof(unsigned int)))) unsigned int'}}
 
   v = gccv;
   __vector unsigned int tv = gccv;
diff --git a/test/Parser/declarators.c b/test/Parser/declarators.c
index 91803c1c5d..31712af26c 100644
--- a/test/Parser/declarators.c
+++ b/test/Parser/declarators.c
@@ -53,7 +53,7 @@ myenum c;      // expected-error {{must use 'enum' tag to refer to type 'myenum'
 float *test7() {
   // We should recover 'b' by parsing it with a valid type of "struct xyz", which
   // allows us to diagnose other bad things done with y, such as this.
-  return &b.y;   // expected-warning {{incompatible pointer types returning 'int *', expected 'float *'}}
+  return &b.y;   // expected-warning {{incompatible pointer types returning 'int *' from a function with result type 'float *'}}
 }
 
 struct xyz test8() { return a; }  // a should be be marked invalid, no diag.
diff --git a/test/Parser/implicit-casts.c b/test/Parser/implicit-casts.c
index 900b4ece8b..a2b31f929f 100644
--- a/test/Parser/implicit-casts.c
+++ b/test/Parser/implicit-casts.c
@@ -14,7 +14,7 @@ void test2() {
 }
 int test3() {
   int a[2];
-  a[0] = test3; // expected-warning{{incompatible pointer to integer conversion assigning 'int ()', expected 'int'}}
+  a[0] = test3; // expected-warning{{incompatible pointer to integer conversion assigning to 'int' from 'int ()'}}
   return 0;
 }
 short x; void test4(char c) { x += c; }
diff --git a/test/Sema/address_spaces.c b/test/Sema/address_spaces.c
index badd2383ab..6258114578 100644
--- a/test/Sema/address_spaces.c
+++ b/test/Sema/address_spaces.c
@@ -37,6 +37,6 @@ struct _st {
 __attribute__((address_space(256))) void * * const base = 0;
 void * get_0(void) {
   return base[0];  // expected-error {{illegal implicit cast between two pointers with different address spaces}} \
-                      expected-warning {{returning 'void __attribute__((address_space(256))) *' discards qualifiers, expected 'void *'}}
+                      expected-warning {{returning 'void __attribute__((address_space(256))) *' from a function with result type 'void *' discards qualifiers}}
 }
 
diff --git a/test/Sema/anonymous-struct-union.c b/test/Sema/anonymous-struct-union.c
index 118854fd47..b91426ca6c 100644
--- a/test/Sema/anonymous-struct-union.c
+++ b/test/Sema/anonymous-struct-union.c
@@ -101,4 +101,4 @@ struct s2 {
 typedef struct {
   int x;
 } a_struct;
-int tmp = (a_struct) { .x = 0 }; // expected-error {{incompatible type initializing 'a_struct', expected 'int'}}
+int tmp = (a_struct) { .x = 0 }; // expected-error {{initializing 'int' from an expression of incompatible type 'a_struct'}}
diff --git a/test/Sema/array-constraint.c b/test/Sema/array-constraint.c
index 66f15c3a3c..8b577fa5d7 100644
--- a/test/Sema/array-constraint.c
+++ b/test/Sema/array-constraint.c
@@ -46,7 +46,7 @@ typedef int TA[I]; // expected-error {{variable length array declaration not all
 void strFunc(char *);
 const char staticAry[] = "test";
 void checkStaticAry() { 
-  strFunc(staticAry); // expected-warning{{passing 'char const [5]' discards qualifiers, expected 'char *'}}
+  strFunc(staticAry); // expected-warning