Bug #:

Submitted by:
Reviewed by:

The following code illustrates a bug in the semantic analysis for assignments:

int func() {
  int *P;
  char *x;
  P = x; // type of this assignment expression should be "int *", NOT "char *".
}

While the type checking/diagnostics are correct, the type of the assignment
expression is incorrect (which shows up during code gen).  With the fix,
the llvm code looks correct...

[dylan:~/llvm/tools/clang] admin% ../../Debug/bin/clang cast.c -emit-llvm
cast.c:4:5: warning: incompatible pointer types assigning 'char *' to 'int *'
  P = x; // type of assignment expression is "int *", NOT "char *".
  ~ ^ ~
; ModuleID = 'foo'

define i32 @func() {
entry:
        %P = alloca i32*                ; <i32**> [#uses=1]
        %x = alloca i8*         ; <i8**> [#uses=1]
        %allocapt = bitcast i32 undef to i32            ; <i32> [#uses=0]
        %tmp = load i8** %x             ; <i8*> [#uses=1]
        %conv = bitcast i8* %tmp to i32*                ; <i32*> [#uses=1]
        store i32* %conv, i32** %P
        ret i32 undef
}

Even though the fix was simple, I decided to rename/refactor the surrounding code
to make a clearer distinction between constraint checking and conversion.

- Renamed AssignmentConversionResult -> AssignmentCheckResult.
- Renamed UsualAssignmentConversions -> CheckAssignmentConstraints.
- Changed the return type of CheckAssignmentConstraints and CheckPointerTypesForAssignment
from QualType -> AssignmentCheckResult. These routines no longer take a reference to the result (obviously).
- Changed CheckAssignmentOperands to return the correct type (with spec annotations).

llvm-svn: 39601