[libclang] Extend clang_Cursor_Evaluate().

[ckandeler]

Summary

Let this function (try to) evaluate expressions, in addition to
declarations and compound statements.

[jkorous]

LGTM

[ckandeler]

Thanks for the quick review. I don't have commit access, so can someone please commit it for me?

[nik]

@jkorous: Please submit. I can't as my svn account is still not ported to github... :/

[ckandeler]

A kind reminder that I need someone with commit rights to merge this for me.

clang/include/clang-c/Index.h

  * Evaluation result of a cursor
  */
 typedef void *CXEvalResult;
 
 /**
  * If cursor is a statement declaration tries to evaluate the
  * statement and if its variable, tries to evaluate its initializer,
  * into its corresponding type.
+ * If it's an expression, tries to evaluate the expression.
  */
 CINDEX_LINKAGE CXEvalResult clang_Cursor_Evaluate(CXCursor C);
 
 /**
  * Returns the kind of the evaluated result.
  */
 CINDEX_LINKAGE CXEvalResultKind clang_EvalResult_getKind(CXEvalResult E);
 

clang/test/Index/evaluate-cursor.cpp

 
 long long HUGE_NEG = -(1ll << 35);
 
 template <typename d> class e {
   using f = d;
   static const auto g = alignof(f);
 };
 
+constexpr static int calc_val() { return 1 + 2; }
+const auto the_value = calc_val() + sizeof(char);
+
 // RUN: c-index-test -evaluate-cursor-at=%s:4:7 \
 // RUN:    -evaluate-cursor-at=%s:8:7 \
 // RUN:    -evaluate-cursor-at=%s:8:11 -std=c++11 %s | FileCheck %s
 // CHECK: Value: 10
 // CHECK: Value: 11
 // CHECK: Value: 11
 
 // RUN: c-index-test -get-macro-info-cursor-at=%s:11:9 \

 // CHECK-LONG: unsigned, Value: 9223372036854775808
 // CHECK-LONG: Value: -34359738368
 
 // RUN: c-index-test -evaluate-cursor-at=%s:18:20 \
 // RUN:    -evaluate-cursor-at=%s:20:20 \
 // RUN:    -evaluate-cursor-at=%s:26:21 \
 // RUN:    -std=c++11 %s | FileCheck -check-prefix=CHECK-DOES-NOT-CRASH %s
 // CHECK-DOES-NOT-CRASH: Not Evaluatable
+
+// RUN: c-index-test -evaluate-cursor-at=%s:30:1 \
+// RUN:    -evaluate-cursor-at=%s:30:32 \
+// RUN:    -evaluate-cursor-at=%s:30:35 \
+// RUN:    -evaluate-cursor-at=%s:30:37 -std=c++11 %s | FileCheck %s -check-prefix=CHECK-EXPR
+// CHECK-EXPR: unsigned, Value: 4
+// CHECK-EXPR: Value: 3
+// CHECK-EXPR: unsigned, Value: 4
+// CHECK-EXPR: unsigned, Value: 1

clang/tools/libclang/CIndex.cpp

static const Expr *evaluateCompoundStmtExpr(const CompoundStmt *CS) {
   for (auto *bodyIterator : CS->body()) {
     if (const auto *E = dyn_cast<Expr>(bodyIterator))
       return E;
   }
   return nullptr;
 }
 
 CXEvalResult clang_Cursor_Evaluate(CXCursor C) {
-  if (const Expr *E =
-          clang_getCursorKind(C) == CXCursor_CompoundStmt
-              ? evaluateCompoundStmtExpr(cast<CompoundStmt>(getCursorStmt(C)))
-              : evaluateDeclExpr(getCursorDecl(C)))
+  const Expr *E = nullptr;
+  if (clang_getCursorKind(C) == CXCursor_CompoundStmt)
+    E = evaluateCompoundStmtExpr(cast<CompoundStmt>(getCursorStmt(C)));
+  else if (clang_isDeclaration(C.kind))
+    E = evaluateDeclExpr(getCursorDecl(C));
+  else if (clang_isExpression(C.kind))
+    E = getCursorExpr(C);
+  if (E)
     return const_cast<CXEvalResult>(
         reinterpret_cast<const void *>(evaluateExpr(const_cast<Expr *>(E), C)));
   return nullptr;
 }
 
 unsigned clang_Cursor_hasAttrs(CXCursor C) {
   const Decl *D = getCursorDecl(C);
   if (!D) {