[libclang] Extend clang_Cursor_Evaluate().

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

Patch by Christian Kandeler <[email protected]>

Reviewers: nik, akyrtzi, arphaman, jkorous

Reviewed By: jkorous

Differential Revision: https://reviews.llvm.org/D80279

Author: ckandeler

clang/include/clang-c/Index.h

@@ -5934,6 +5934,7 @@ 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);
 

clang/test/Index/evaluate-cursor.cpp

@@ -26,6 +26,9 @@ template <typename d> class e {
   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
@@ -53,3 +56,12 @@ template <typename d> class e {
 // 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

@@ -4056,10 +4056,14 @@ static const Expr *evaluateCompoundStmtExpr(const CompoundStmt *CS) {
 }
 
 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;