This PR is a request for better array bounds diagnostics. The C++ FE says "multidimensional array must have bounds for all dimensions except the first", and we can do something similar in the C FE.
Bootstrapped/regtested on x86_64-linux, ok for trunk? 2016-01-14 Marek Polacek <pola...@redhat.com> PR c/69262 * c-decl.c (grokdeclarator): Provide more information for invalid array declarations. * gcc.dg/array-15.c: New test. diff --git gcc/c/c-decl.c gcc/c/c-decl.c index 915376d..1644478 100644 --- gcc/c/c-decl.c +++ gcc/c/c-decl.c @@ -5951,6 +5951,18 @@ grokdeclarator (const struct c_declarator *declarator, { error_at (loc, "array type has incomplete element type %qT", type); + /* See if we can be more helpful. */ + if (TREE_CODE (type) == ARRAY_TYPE) + { + if (name) + inform (loc, "declaration of %qE as multidimensional " + "array must have bounds for all dimensions " + "except the first", name); + else + inform (loc, "declaration of multidimensional array " + "must have bounds for all dimensions except " + "the first"); + } type = error_mark_node; } else diff --git gcc/testsuite/gcc.dg/array-15.c gcc/testsuite/gcc.dg/array-15.c index e69de29..a002f68 100644 --- gcc/testsuite/gcc.dg/array-15.c +++ gcc/testsuite/gcc.dg/array-15.c @@ -0,0 +1,52 @@ +/* PR c/69262 */ +/* { dg-do compile } */ +/* { dg-options "-std=c11 -pedantic-errors" } */ + +struct S +{ + int a[1][][2]; /* { dg-error "array type has incomplete element type" } */ + /* { dg-message "declaration of .a. as multidimensional array must have bounds" "" { target *-*-* } 7 } */ +}; + +struct R +{ + int i; + int a[][]; /* { dg-error "array type has incomplete element type" } */ + /* { dg-message "declaration of .a. as multidimensional array must have bounds" "" { target *-*-* } 14 } */ +}; + +typedef int T[]; +typedef int U[][]; /* { dg-error "array type has incomplete element type" } */ +/* { dg-message "declaration of .U. as multidimensional array must have bounds" "" { target *-*-* } 19 } */ + +int x[][]; /* { dg-error "array type has incomplete element type" } */ +/* { dg-message "declaration of .x. as multidimensional array must have bounds" "" { target *-*-* } 22 } */ + +struct N; + +void +fn1 (int z[][]) /* { dg-error "array type has incomplete element type" } */ +/* { dg-message "declaration of .z. as multidimensional array must have bounds" "" { target *-*-* } 28 } */ +{ + int a[1][][2]; /* { dg-error "array type has incomplete element type" } */ + /* { dg-message "declaration of .a. as multidimensional array must have bounds" "" { target *-*-* } 31 } */ + /* OK */ + int b[3][2][1]; + int c[1][2][3][]; /* { dg-error "array type has incomplete element type" } */ + /* { dg-message "declaration of .c. as multidimensional array must have bounds" "" { target *-*-* } 35 } */ + T d[1]; /* { dg-error "array type has incomplete element type" } */ + /* { dg-message "declaration of .d. as multidimensional array must have bounds" "" { target *-*-* } 37 } */ + T e[]; /* { dg-error "array type has incomplete element type" } */ + /* { dg-message "declaration of .e. as multidimensional array must have bounds" "" { target *-*-* } 39 } */ + + /* This array has incomplete element type, but is not multidimensional. */ + struct N f[1]; /* { dg-error "array type has incomplete element type" } */ + /* { dg-bogus "declaration of .f. as multidimensional array must have bounds" "" { target *-*-* } 43 } */ +} + +void fn2 (int [][]); /* { dg-error "array type has incomplete element type" } */ +/* { dg-message "declaration of multidimensional array must have bounds" "" { target *-*-* } 47 } */ +/* OK */ +void fn3 (int [][*]); +void fn4 (T []); /* { dg-error "array type has incomplete element type" } */ +/* { dg-message "declaration of multidimensional array must have bounds" "" { target *-*-* } 51 } */ Marek