Author: Aaron Ballman Date: 2024-04-01T14:54:03-04:00 New Revision: cbd48b184eca1ca73e6f20575501d94ad30fbd58
URL: https://github.com/llvm/llvm-project/commit/cbd48b184eca1ca73e6f20575501d94ad30fbd58 DIFF: https://github.com/llvm/llvm-project/commit/cbd48b184eca1ca73e6f20575501d94ad30fbd58.diff LOG: [C99] Claim conformance to "conversion of array to pointer not limited to lvalues" We don't have a document number for this, but the change was called out explicitly in the editor's comments in the C99 foreword. Added: clang/test/C/C99/array-lvalue.c Modified: clang/www/c_status.html Removed: ################################################################################ diff --git a/clang/test/C/C99/array-lvalue.c b/clang/test/C/C99/array-lvalue.c new file mode 100644 index 00000000000000..4e963b4f74fc32 --- /dev/null +++ b/clang/test/C/C99/array-lvalue.c @@ -0,0 +1,38 @@ +/* RUN: %clang_cc1 -verify -pedantic -std=c99 %s + RUN: %clang_cc1 -verify=c89 -pedantic -std=c89 %s + expected-no-diagnostics + */ + +/* WG14 ???: Yes + * Conversion of array to pointer not limited to lvalues + * + * NB: the original paper number is unknown, this was gleaned from the editor's report + * in the C99 foreword. The C99 rationale document did not shed much light on + * the situation either, mostly talking about user confusion between lvalue and + * modifiable lvalue. However, the crux of the change was C89 changing: + * + * C89 3.2.2.1: Except when it is the operand of ..., an lvalue that has type + * 'array of type' is converted to an expression that has type 'pointer to + * type' that points to the initial element of the array object and is not an + * lvalue. + * + * C99 6.3.2.1p3: Except when it is the operand of ..., an expression that has + * type 'array of type' is converted to an expression with type 'pointer to + * type' that points to the initial element of the array object and is not an + * lvalue. + */ + +struct S { + char arr[100]; +}; + +struct S f(void); + +void func(void) { + char c; + /* The return from f() is an rvalue, so this code is not valid in C89, but is + * valid in C99. + */ + c = f().arr[10]; /* c89-warning {{ISO C90 does not allow subscripting non-lvalue array}} */ +} + diff --git a/clang/www/c_status.html b/clang/www/c_status.html index 123897593e5d84..803dce8e29fc04 100644 --- a/clang/www/c_status.html +++ b/clang/www/c_status.html @@ -360,7 +360,7 @@ <h2 id="c99">C99 implementation status</h2> <tr> <td>conversion of array to pointer not limited to lvalues</td> <td>Unknown</td> - <td class="unknown" align="center">Unknown</td> + <td class="full" align="center">Yes</td> </tr> <tr> <td>relaxed constraints on aggregate and union initialization</td> _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
