[Cleanup] Remove using namespace tvm::runtime from headers
#17246
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Lunderberg
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Aug 6, 2024
Re-apply the change from upstream apache#16343. See apache#17246 for an example of the type of bug that can result from MSVC's default non-standard name resolution.
tqchen
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tqchen
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Aug 7, 2024
Good point. I think this change is beneficial regardless of #16183, but the FFI changes touch so many parts of TVM that I wouldn't want to declare them 100% independent. |
Prior to this commit, various header files had `using namespace tvm::runtime`, which imports all names from `tvm::runtime` into the current namespace. These imports can cause compilation errors depending on the order of `#include` statements. For example, the `#include <tvm/relay/attrs/transform.h>` file uses the unqualified name `Bool` to refer to `::tvm::Bool`, a subclass of `PrimExpr`. If a different header file specifies `using namespace tvm::runtime` within the `tvm::relay` namespace, then the unqualified name `Bool` ambiguously refers to either `::tvm::Bool` or `::tvm::runtime::Bool`. In MSVC, this can cause even further compilation errors. By default, MSVC does not follow the C++ standard for name resolution in templates. The standard requires that any names in a template that do not depend on template parameters be resolved when the template is declared. However, MSVC instead resolves these names when the template is instantiated. As a result, the same `using namespace tvm::runtime` may cause a compilation error if it occurs after the template's declaration, but before the template's usage. (TVM provides the `/permissive-` flag to MSVC builds specifically to disable MSVC's non-standard name resolution, so this only impacts downstream forks that disable this flag. See apache#16343 for more details.) This commit removes `using namespace tvm::runtime`, replacing them with explicit `using tvm::runtime::SOME_SPECIFIC_SYMBOL` where necessary. This resolves both the include-order dependency for standards-compliant compilers, and the compilation errors for MSVC's default build.
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Rebased these changes onto main, and this PR should be land-able now that the performance regressions from #16183 have been resolved. |
tqchen
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Aug 22, 2024
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Prior to this commit, various header files had
using namespace tvm::runtime, which imports all names fromtvm::runtimeinto the current namespace.These imports can cause compilation errors depending on the order of
#includestatements. For example, the#include <tvm/relay/attrs/transform.h>file uses the unqualified nameBoolto refer to::tvm::Bool, a subclass ofPrimExpr. If a different header file specifiesusing namespace tvm::runtimewithin thetvm::relaynamespace, then the unqualified nameBoolambiguously refers to either::tvm::Boolor::tvm::runtime::Bool.In MSVC, this can cause even further compilation errors. By default, MSVC does not follow the C++ standard for name resolution in templates. The standard requires that any names in a template that do not depend on template parameters be resolved when the template is declared. However, MSVC instead resolves these names when the template is instantiated. As a result, the same
using namespace tvm::runtimemay cause a compilation error if it occurs after the template's declaration, but before the template's usage.(TVM provides the
/permissive-flag to MSVC builds specifically to disable MSVC's non-standard name resolution, so this only impacts downstream forks that disable this flag. See #16343 for more details.)This commit removes
using namespace tvm::runtime, replacing them with explicitusing tvm::runtime::SOME_SPECIFIC_SYMBOLwhere necessary. This resolves both the include-order dependency for standards-compliant compilers, and the compilation errors for MSVC's default build.