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August 01, 2010 [Issue 4565] New: In array literals single values can replace arrays of length 1 | ||||
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http://d.puremagic.com/issues/show_bug.cgi?id=4565 Summary: In array literals single values can replace arrays of length 1 Product: D Version: D2 Platform: x86 OS/Version: Windows Status: NEW Keywords: accepts-invalid Severity: normal Priority: P2 Component: DMD AssignedTo: nobody@puremagic.com ReportedBy: bearophile_hugs@eml.cc --- Comment #0 from bearophile_hugs@eml.cc 2010-08-01 15:27:31 PDT --- This program compiles with no errors with dmd 2.047: int[1][3] a1 = [1, 2, 3]; void main() { int[1][3] a2 = [1, 2, 3]; } But those array literals are wrong. This is the correct program: int[1][3] a1 = [[1], [2], [3]]; void main() { int[1][3] a2 = [[1], [2], [3]]; } A sloppy syntax is bad because it *always* offers space for bugs, like this one, dmd compiles this program with no errors (note the missing comma): int[1][3] a = [[1] [0], [2]]; void main() {} Now a contains [1, 2, 0], a silent bug. This situation is partially caused by bug 3849 -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- |
October 22, 2012 [Issue 4565] In array literals single values can replace arrays of length 1 | ||||
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Posted in reply to bearophile_hugs@eml.cc | http://d.puremagic.com/issues/show_bug.cgi?id=4565 Andrej Mitrovic <andrej.mitrovich@gmail.com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |andrej.mitrovich@gmail.com AssignedTo|nobody@puremagic.com |andrej.mitrovich@gmail.com --- Comment #1 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2012-10-22 16:00:17 PDT --- Do you by any chance have a somewhat elaborate set of test-cases that cover many types of arrays which should and shouldn't compile? It would help to make solid test-cases. Otherwise I'll write them myself, no problem. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- |
October 22, 2012 [Issue 4565] In array literals single values can replace arrays of length 1 | ||||
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Posted in reply to bearophile_hugs@eml.cc | http://d.puremagic.com/issues/show_bug.cgi?id=4565 --- Comment #2 from bearophile_hugs@eml.cc 2012-10-22 16:26:08 PDT --- (In reply to comment #1) > Do you by any chance have a somewhat elaborate set of test-cases that cover many types of arrays which should and shouldn't compile? I don't, sorry. Currently finding such test cases is a laborious manual work. There is no fuzzy testing framework for D, as ones used on the certified C compiler. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- |
October 27, 2012 [Issue 4565] In array literals single values can replace arrays of length 1 | ||||
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Posted in reply to bearophile_hugs@eml.cc | http://d.puremagic.com/issues/show_bug.cgi?id=4565 yebblies <yebblies@gmail.com> changed: What |Removed |Added ---------------------------------------------------------------------------- Keywords| |pull CC| |yebblies@gmail.com Platform|x86 |All OS/Version|Windows |All --- Comment #3 from yebblies <yebblies@gmail.com> 2012-10-28 02:49:25 EST --- https://github.com/D-Programming-Language/dmd/pull/1207 -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- |
November 15, 2012 [Issue 4565] In array literals single values can replace arrays of length 1 | ||||
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Posted in reply to bearophile_hugs@eml.cc | http://d.puremagic.com/issues/show_bug.cgi?id=4565 --- Comment #4 from Kenji Hara <k.hara.pg@gmail.com> 2012-11-15 00:49:19 PST --- (In reply to comment #0) > This program compiles with no errors with dmd 2.047: > > int[1][3] a1 = [1, 2, 3]; > void main() { > int[1][3] a2 = [1, 2, 3]; > } > > But those array literals are wrong. This is the correct program: > > int[1][3] a1 = [[1], [2], [3]]; > void main() { > int[1][3] a2 = [[1], [2], [3]]; > } I think this is not a bad program. > int[1][3] a1 = [1, 2, 3]; is same as: int[1][3] a1 = void; a1[0][] = 1; // fill all elements by 1 a1[1][] = 2; // fill all elements by 2 a1[2][] = 3; // fill all elements by 3 Then a1 is initialized by [[1], [2], [3]]. And it is consistent with: int[3] sa = 1; // sa is initialized to [1, 1, 1] ---- > A sloppy syntax is bad because it *always* offers space for bugs, like this one, dmd compiles this program with no errors (note the missing comma): > > int[1][3] a = [[1] [0], [2]]; > void main() {} [1][0] is an expression which indexing array literal, and evaluated to 1. It's equivalent to: [1,2,3][0] == 1 > Now a contains [1, 2, 0], a silent bug. Now a is initialized by [1, [2]], and is same as: int[1][3] a = void; a[0][] = 1; a[1] = [2]; a[2][] = 0; // == int.init After all, a == [1, 2, 0]. There is no bug. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- |
November 15, 2012 [Issue 4565] In array literals single values can replace arrays of length 1 | ||||
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Posted in reply to bearophile_hugs@eml.cc | http://d.puremagic.com/issues/show_bug.cgi?id=4565 --- Comment #5 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2012-11-15 00:56:56 PST --- > After all, a == [1, 2, 0]. There is no bug. Ok, you can close https://github.com/D-Programming-Language/dmd/pull/1207 if bug is invalid. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- |
March 12, 2013 [Issue 4565] In array literals single values can replace arrays of length 1 | ||||
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Posted in reply to bearophile_hugs@eml.cc | http://d.puremagic.com/issues/show_bug.cgi?id=4565 --- Comment #6 from bearophile_hugs@eml.cc 2013-03-11 19:44:12 PDT --- (In reply to comment #4) Sorry for the very delayed answer. > > A sloppy syntax is bad because it *always* offers space for bugs, like this one, dmd compiles this program with no errors (note the missing comma): > > > > int[1][3] a = [[1] [0], [2]]; > > void main() {} > > [1][0] is an expression which indexing array literal, and evaluated to 1. It's equivalent to: [1,2,3][0] == 1 > > > Now a contains [1, 2, 0], a silent bug. > > Now a is initialized by [1, [2]], and is same as: > int[1][3] a = void; > a[0][] = 1; > a[1] = [2]; > a[2][] = 0; // == int.init > > After all, a == [1, 2, 0]. There is no bug. In my opinion that's probably a bug in user code. I doubt the user meant to write that. Most probably the user meant to write this, but missed a comma after the first sub-array: int[1][3] a = [[1], [0], [2]]; void main() {} But this is an uncommon situation, so I think it's not worth thinking too much about it. What follows is more important: > I think this is not a bad program. > > int[1][3] a1 = [1, 2, 3]; > is same as: > > int[1][3] a1 = void; > a1[0][] = 1; // fill all elements by 1 > a1[1][] = 2; // fill all elements by 2 > a1[2][] = 3; // fill all elements by 3 > > Then a1 is initialized by [[1], [2], [3]]. > > And it is consistent with: > int[3] sa = 1; // sa is initialized to [1, 1, 1] Today this syntax compiles: void main() { int[1][3] a2; a2[0][] = 1; a2[1][] = 2; a2[2][] = 3; } This used to compile fine, but today it gives warnings (and this is good): void main() { int[1][3] a3; a3[0] = 1; a3[1] = 2; a3[2] = 3; } temp.d(3): Warning: explicit element-wise assignment (a3[cast(uint)0])[] = 1 is better than a3[cast(uint)0] = 1 temp.d(4): Warning: explicit element-wise assignment (a3[cast(uint)1])[] = 2 is better than a3[cast(uint)1] = 2 temp.d(5): Warning: explicit element-wise assignment (a3[cast(uint)2])[] = 3 is better than a3[cast(uint)2] = 3 Currently both of the following forms are accepted: void main() { int[1][3] a1 = [[1], [2], [3]]; int[1][3] a2 = [1, 2, 3]; } Generally I trust your good judgement Hara, but if we are going to deprecate the assignment of array slices without using [], then I don't know if the idea of allowing both of those syntaxes is a good idea... -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- |
May 31, 2013 [Issue 4565] In array literals single values can replace arrays of length 1 | ||||
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Posted in reply to bearophile_hugs@eml.cc | http://d.puremagic.com/issues/show_bug.cgi?id=4565 Shriramana Sharma <samjnaa@gmail.com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |samjnaa@gmail.com --- Comment #7 from Shriramana Sharma <samjnaa@gmail.com> 2013-05-31 10:33:43 PDT --- (In reply to comment #4) > > I think this is not a bad program. > > int[1][3] a1 = [1, 2, 3]; > is same as: > > int[1][3] a1 = void; > a1[0][] = 1; // fill all elements by 1 > a1[1][] = 2; // fill all elements by 2 > a1[2][] = 3; // fill all elements by 3 > > Then a1 is initialized by [[1], [2], [3]]. > > And it is consistent with: > int[3] sa = 1; // sa is initialized to [1, 1, 1] FWIW I agree with bearophile here. In the case of having a single value on the RHS it is easy (?) to construe how int[3] a = 1 (or even maybe int[3][3] a = 1) would initialize all the elements, but when you specify an array literal on the RHS, I think it should have the same shape as the array specified in the type on the LHS to avoid hard-to-find bugs. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- |
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