ram7bhupal created this revision.
ram7bhupal added reviewers: dblaikie, aaron.ballman.
ram7bhupal requested review of this revision.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.
-Wdeclaration-after-statement doesn't do anything if combined with -std=c99 or
newer.
Take a look at the following program:
// prog.c
#include <stdio.h>
int main(void)
{
printf("hello world\n");
int i = 0;
return 0;
}
If I compile it with clang with the following command:
$ clang -std=c99 -Wdeclaration-after-statement prog.c
it produces no warnings.
If I compile the same code with gcc with the following command:
$ gcc -std=c99 -Wdeclaration-after-statement prog.c
it produces the following warning:
prog.c: In function ‘main’:
prog.c:6:9: warning: ISO C90 forbids mixed declarations and code
[-Wdeclaration-after-statement]
6 | int i = 0;
| ^~~
This is the behavior I would like to have with clang, but it only produces this
warning if I use it with -std=c90 or -std=c89 or -ansi, like this:
$ clang -std=c90 -Wdeclaration-after-statement prog.c
prog.c:6:6: warning: ISO C90 forbids mixing declarations and code
[-Wdeclaration-after-statement]
int i = 0;
^
1 warning generated.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D115094
Files:
clang/lib/Sema/SemaStmt.cpp
Index: clang/lib/Sema/SemaStmt.cpp
===================================================================
--- clang/lib/Sema/SemaStmt.cpp
+++ clang/lib/Sema/SemaStmt.cpp
@@ -410,9 +410,9 @@
ArrayRef<Stmt *> Elts, bool isStmtExpr) {
const unsigned NumElts = Elts.size();
- // If we're in C89 mode, check that we don't have any decls after stmts. If
+ // Check that we don't have any decls after stmts. If
// so, emit an extension diagnostic.
- if (!getLangOpts().C99 && !getLangOpts().CPlusPlus) {
+ if (!getLangOpts().CPlusPlus) {
// Note that __extension__ can be around a decl.
unsigned i = 0;
// Skip over all declarations.
Index: clang/lib/Sema/SemaStmt.cpp
===================================================================
--- clang/lib/Sema/SemaStmt.cpp
+++ clang/lib/Sema/SemaStmt.cpp
@@ -410,9 +410,9 @@
ArrayRef<Stmt *> Elts, bool isStmtExpr) {
const unsigned NumElts = Elts.size();
- // If we're in C89 mode, check that we don't have any decls after stmts. If
+ // Check that we don't have any decls after stmts. If
// so, emit an extension diagnostic.
- if (!getLangOpts().C99 && !getLangOpts().CPlusPlus) {
+ if (!getLangOpts().CPlusPlus) {
// Note that __extension__ can be around a decl.
unsigned i = 0;
// Skip over all declarations.
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