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111
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1 /* Test for handling of tags. "const struct foo;" and similar does
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2 not redeclare an existing tag. */
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3 /* Origin: Joseph Myers <jsm@polyomino.org.uk> */
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4 /* { dg-do compile } */
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5 /* { dg-options "-std=iso9899:1999 -pedantic-errors" } */
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6
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7 /* Plain "struct s;" always declares a tag: the same as one declared
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8 in that scope, or shadowing one from an outer scope. */
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9 struct s0;
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10 struct s0 { int a; };
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11 struct s0;
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12 void f (void) { struct s0; }
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13
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14 /* A declaration with a qualifier or storage class specifier declares
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15 the tag if no other declaration of it is visible. */
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16 const union u0; /* { dg-warning "13:useless type qualifier in empty declaration" } */
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17 union u0 { long b; };
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18
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19 extern struct s1; /* { dg-warning "15:useless storage class specifier in empty declaration" } */
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20
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21 /* But if a declaration of the tag is visible, whether at the same
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22 scope or an outer scope, the declaration specifies the same type as
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23 the previous declaration and does not redeclare the tag (C99
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24 6.7.2.3#8). Thus, as it does not declare a declarator, a tag or
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25 the members of an enumeration, it is a constraint violation. */
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26
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27 struct s2 { char x; };
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28 const struct s2; /* { dg-error "14:empty declaration with type qualifier does not redeclare tag" } */
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29
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30 union u1;
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31 extern union u1; /* { dg-error "14:empty declaration with storage class specifier does not redeclare tag" } */
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32
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33 union u2 { long b; };
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34 void g(void) { const union u2; } /* { dg-error "28:empty declaration with type qualifier does not redeclare tag" } */
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35
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36 /* And it does not redeclare the tag either if the outer tag is the
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37 wrong kind of tag. This also yields an error for the reference to
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38 the wrong kind of tag in addition to the pedwarn for the empty
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39 declaration. */
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40
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41 union u3 { float v; };
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42 void h(void) { const struct u3; } /* { dg-error "29:'u3' defined as wrong kind of tag" } */
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43 /* { dg-error "29:empty declaration with type qualifier does not redeclare tag" "wrong tag empty" { target *-*-* } .-1 } */
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44
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45 /* However, such useless specifiers are OK if the contents of the tag
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46 are being defined, or shadowed in an inner scope with the contents
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47 included in the shadowing. */
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48
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49 struct s3;
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50 const struct s3 { int a; }; /* { dg-warning "14:useless type qualifier in empty declaration" } */
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51
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52 union u4;
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53 extern union u4 { int z; }; /* { dg-warning "14:useless storage class specifier in empty declaration" } */
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54
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55 enum e0 { E0 };
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56 void i(void) { const enum e0 { E1 }; } /* { dg-warning "32:useless type qualifier in empty declaration" } */
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57
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58 union u5 { int p; };
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59 void j(void) { extern struct u5 { int q; }; } /* { dg-warning "30:useless storage class specifier in empty declaration" } */
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