mirror of
https://github.com/bazelbuild/rules_cc
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204 lines
7.5 KiB
Python
204 lines
7.5 KiB
Python
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# Copyright 2020 The Bazel Authors. All rights reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""Utility functions for C++ rules."""
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# LINT.IfChange
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def _lookup_var(ctx, additional_vars, var):
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expanded_make_var_ctx = ctx.var.get(var)
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expanded_make_var_additional = additional_vars.get(var)
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if expanded_make_var_additional != None:
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return expanded_make_var_additional
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if expanded_make_var_ctx != None:
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return expanded_make_var_ctx
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fail("{}: {} not defined".format(ctx.label, "$(" + var + ")"))
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def _expand_nested_variable(ctx, additional_vars, exp, execpath = True, targets = []):
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# If make variable is predefined path variable(like $(location ...))
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# we will expand it first.
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if exp.find(" ") != -1:
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if not execpath:
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if exp.startswith("location"):
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exp = exp.replace("location", "rootpath", 1)
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data_targets = []
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if ctx.attr.data != None:
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data_targets = ctx.attr.data
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# Make sure we do not duplicate targets.
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unified_targets_set = {}
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for data_target in data_targets:
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unified_targets_set[data_target] = True
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for target in targets:
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unified_targets_set[target] = True
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return ctx.expand_location("$({})".format(exp), targets = unified_targets_set.keys())
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# Recursively expand nested make variables, but since there is no recursion
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# in Starlark we will do it via for loop.
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unbounded_recursion = True
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# The only way to check if the unbounded recursion is happening or not
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# is to have a look at the depth of the recursion.
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# 10 seems to be a reasonable number, since it is highly unexpected
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# to have nested make variables which are expanding more than 10 times.
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for _ in range(10):
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exp = _lookup_var(ctx, additional_vars, exp)
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if len(exp) >= 3 and exp[0] == "$" and exp[1] == "(" and exp[len(exp) - 1] == ")":
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# Try to expand once more.
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exp = exp[2:len(exp) - 1]
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continue
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unbounded_recursion = False
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break
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if unbounded_recursion:
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fail("potentially unbounded recursion during expansion of {}".format(exp))
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return exp
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def _expand(ctx, expression, additional_make_variable_substitutions, execpath = True, targets = []):
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idx = 0
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last_make_var_end = 0
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result = []
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n = len(expression)
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for _ in range(n):
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if idx >= n:
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break
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if expression[idx] != "$":
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idx += 1
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continue
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idx += 1
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# We've met $$ pattern, so $ is escaped.
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if idx < n and expression[idx] == "$":
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idx += 1
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result.append(expression[last_make_var_end:idx - 1])
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last_make_var_end = idx
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# We might have found a potential start for Make Variable.
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elif idx < n and expression[idx] == "(":
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# Try to find the closing parentheses.
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make_var_start = idx
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make_var_end = make_var_start
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for j in range(idx + 1, n):
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if expression[j] == ")":
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make_var_end = j
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break
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# Note we cannot go out of string's bounds here,
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# because of this check.
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# If start of the variable is different from the end,
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# we found a make variable.
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if make_var_start != make_var_end:
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# Some clarifications:
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# *****$(MAKE_VAR_1)*******$(MAKE_VAR_2)*****
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# ^ ^ ^
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# | | |
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# last_make_var_end make_var_start make_var_end
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result.append(expression[last_make_var_end:make_var_start - 1])
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make_var = expression[make_var_start + 1:make_var_end]
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exp = _expand_nested_variable(ctx, additional_make_variable_substitutions, make_var, execpath, targets)
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result.append(exp)
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# Update indexes.
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idx = make_var_end + 1
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last_make_var_end = idx
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# Add the last substring which would be skipped by for loop.
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if last_make_var_end < n:
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result.append(expression[last_make_var_end:n])
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return "".join(result)
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def _get_expanded_env(ctx, additional_make_variable_substitutions):
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if not hasattr(ctx.attr, "env"):
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fail("could not find rule attribute named: 'env'")
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expanded_env = {}
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for k in ctx.attr.env:
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expanded_env[k] = _expand(
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ctx,
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ctx.attr.env[k],
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additional_make_variable_substitutions,
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# By default, Starlark `ctx.expand_location` has `execpath` semantics.
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# For legacy attributes, e.g. `env`, we want `rootpath` semantics instead.
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execpath = False,
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)
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return expanded_env
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# Implementation of Bourne shell tokenization.
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# Tokenizes str and appends result to the options list.
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def _tokenize(options, options_string):
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token = []
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force_token = False
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quotation = "\0"
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length = len(options_string)
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# Since it is impossible to modify loop variable inside loop
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# in Starlark, and also there is no while loop, I have to
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# use this ugly hack.
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i = -1
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for _ in range(length):
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i += 1
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if i >= length:
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break
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c = options_string[i]
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if quotation != "\0":
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# In quotation.
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if c == quotation:
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# End quotation.
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quotation = "\0"
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elif c == "\\" and quotation == "\"":
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i += 1
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if i == length:
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fail("backslash at the end of the string: {}".format(options_string))
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c = options_string[i]
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if c != "\\" and c != "\"":
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token.append("\\")
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token.append(c)
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else:
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# Regular char, in quotation.
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token.append(c)
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else:
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# Not in quotation.
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if c == "'" or c == "\"":
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# Begin single double quotation.
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quotation = c
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force_token = True
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elif c == " " or c == "\t":
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# Space not quoted.
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if force_token or len(token) > 0:
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options.append("".join(token))
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token = []
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force_token = False
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elif c == "\\":
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# Backslash not quoted.
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i += 1
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if i == length:
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fail("backslash at the end of the string: {}".format(options_string))
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token.append(options_string[i])
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else:
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# Regular char, not quoted.
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token.append(c)
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if quotation != "\0":
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fail("unterminated quotation at the end of the string: {}".format(options_string))
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if force_token or len(token) > 0:
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options.append("".join(token))
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cc_helper = struct(
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get_expanded_env = _get_expanded_env,
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tokenize = _tokenize,
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)
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# LINT.ThenChange(https://github.com/bazelbuild/bazel/blob/master/src/main/starlark/builtins_bzl/common/cc/cc_helper.bzl)
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