[Parse] Make -Wgcc-compat complain about for loop inits in C89

While clang allows declarations in for loop init statements in c89 and
gnu89, gcc does not. So, we should probably warn if users care about gcc
compatibility.

Differential Revision: https://reviews.llvm.org/D47840

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@335927 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/clang/Basic/DiagnosticParseKinds.td b/include/clang/Basic/DiagnosticParseKinds.td
index c2a1f095f17d7b2e8bab193f73fdcfb341ca53ac..dd4c81922592f4600160fa0581d2f4ff93f2bbfe 100644 (file)
--- a/include/clang/Basic/DiagnosticParseKinds.td
+++ b/include/clang/Basic/DiagnosticParseKinds.td
@@ -173,6 +173,9 @@ def warn_attribute_on_function_definition : Warning<
 def warn_gcc_attribute_location : Warning<
   "GCC does not allow an attribute in this position on a function declaration">, 
   InGroup<GccCompat>;
+def warn_gcc_variable_decl_in_for_loop : Warning<
+  "GCC does not allow variable declarations in for loop initializers before "
+  "C99">, InGroup<GccCompat>;
 def warn_attribute_no_decl : Warning<
   "attribute %0 ignored, because it is not attached to a declaration">, 
   InGroup<IgnoredAttributes>;

diff --git a/lib/Parse/ParseStmt.cpp b/lib/Parse/ParseStmt.cpp
index 8c4a3056ec0ec9639118c9b4a1a61e4d5629fc12..107fa556372848339b0a68c0fb7135120fa4c4bf 100644 (file)
--- a/lib/Parse/ParseStmt.cpp
+++ b/lib/Parse/ParseStmt.cpp
@@ -1624,8 +1624,10 @@ StmtResult Parser::ParseForStatement(SourceLocation *TrailingElseLoc) {
     ParenBraceBracketBalancer BalancerRAIIObj(*this);
 
     // Parse declaration, which eats the ';'.
-    if (!C99orCXXorObjC)   // Use of C99-style for loops in C90 mode?
+    if (!C99orCXXorObjC) {   // Use of C99-style for loops in C90 mode?
       Diag(Tok, diag::ext_c99_variable_decl_in_for_loop);
+      Diag(Tok, diag::warn_gcc_variable_decl_in_for_loop);
+    }
 
     // In C++0x, "for (T NS:a" might not be a typo for ::
     bool MightBeForRangeStmt = getLangOpts().CPlusPlus;

diff --git a/test/Parser/gcc-for-loop-init-compatibility.c b/test/Parser/gcc-for-loop-init-compatibility.c
new file mode 100644 (file)
index 0000000..dc88f08
--- /dev/null
+++ b/test/Parser/gcc-for-loop-init-compatibility.c
@@ -0,0 +1,15 @@
+// RUN: %clang_cc1 -std=c89 -fsyntax-only -verify %s
+// RUN: %clang_cc1 -std=gnu89 -fsyntax-only -verify %s
+// RUN: %clang_cc1 -std=c99 -fsyntax-only -verify %s -DC99
+
+#ifdef C99
+// expected-no-diagnostics
+#endif
+
+void foo() {
+#ifndef C99
+  // expected-warning@+2{{GCC does not allow variable declarations in for loop initializers before C99}}
+#endif
+  for (int i = 0; i < 10; i++)
+    ;
+}