Resolve #851: update references to default branch to use "main"

.github/workflows/ci_build_library.yaml

@@ -18,7 +18,6 @@ run-name: Build the library on different platforms and run tests
 on:
   push:
     branches:
-      - master
       - main
 
   pull_request:

.github/workflows/ci_build_wheels.yaml

@@ -18,7 +18,6 @@ run-name: Build Python wheels and verify them
 on:
   push:
     branches:
-      - master
       - main
 
   pull_request:

.github/workflows/ci_docker_tests.yaml

@@ -18,7 +18,6 @@ run-name: Build Docker images and test them
 on:
   push:
     branches:
-      - master
       - main
 
   pull_request:

.github/workflows/ci_format_checks.yml

@@ -18,7 +18,6 @@ run-name: Check source code with linters and formatters
 on:
   push:
     branches:
-      - master
       - main
 
   pull_request:

.github/workflows/ci_hardware_options.yaml

@@ -18,7 +18,6 @@ run-name: Test with instruction set extensions and parallelism
 on:
   push:
     branches:
-      - master
       - main
 
   pull_request:

.github/workflows/ci_sanitizer_tests.yaml

@@ -18,7 +18,6 @@ run-name: Test with address and memory sanitizers
 on:
   push:
     branches:
-      - master
       - main
 
   pull_request:

.github/workflows/ci_tcmalloc_test.yaml

@@ -18,7 +18,6 @@ run-name: Test with TCMalloc (thread-caching malloc)
 on:
   push:
     branches:
-      - master
       - main
 
   pull_request:

.github/workflows/osv-scanner.yaml

@@ -31,7 +31,6 @@ on:
     types: [opened, synchronize]
     branches:
       - main
-      - master
 
   # Support merge queues.
   merge_group:

.github/workflows/scorecard-scanner.yaml

@@ -29,7 +29,6 @@ on:
     types: [opened, synchronize]
     branches:
       - main
-      - master
 
   # Support merge queues.
   merge_group:

README.md

@@ -56,9 +56,9 @@ vol. 574](https://www.nature.com/articles/s41586-019-1666-5), 2019).
 ### C++ usage
 
 The code is basically designed as a library. The user can modify sample
-applications in [apps](https://github.com/quantumlib/qsim/tree/master/apps)
+applications in [apps](https://github.com/quantumlib/qsim/tree/main/apps)
 to meet their own needs. The usage of sample applications is described in the
-[docs](https://github.com/quantumlib/qsim/blob/master/docs/usage.md).
+[docs](https://github.com/quantumlib/qsim/blob/main/docs/usage.md).
 
 ### Python usage
 
@@ -78,7 +78,7 @@ conda install -c conda-forge qsimcirq
 ```
 
 _Note_: The core qsim library (located in the source repository under the
-[`lib/`](https://github.com/quantumlib/qsim/blob/master/lib) subdirectory) can
+[`lib/`](https://github.com/quantumlib/qsim/blob/main/lib) subdirectory) can
 be included directly in C++ programs without installing the Python interface.
 
 ### Cirq usage
@@ -87,31 +87,31 @@ be included directly in C++ programs without installing the Python interface.
 invoking Noisy Intermediate-Scale Quantum (NISQ) circuits. Cirq can use qsim
 as its simulation library. To get started with simulating Cirq circuits using
 qsim, please refer to the
-[tutorial](https://github.com/quantumlib/qsim/blob/master/docs/tutorials/qsimcirq.ipynb).
+[tutorial](https://github.com/quantumlib/qsim/blob/main/docs/tutorials/qsimcirq.ipynb).
 
 More detailed information about the qsim-Cirq API can be found in the
-[docs](https://github.com/quantumlib/qsim/blob/master/docs/cirq_interface.md).
+[docs](https://github.com/quantumlib/qsim/blob/main/docs/cirq_interface.md).
 
 ### Input format
 
 > [!WARNING]
 > This format is deprecated, and no longer actively maintained.
 
 The circuit input format is described in the
-[docs](https://github.com/quantumlib/qsim/blob/master/docs/input_format.md).
+[docs](https://github.com/quantumlib/qsim/blob/main/docs/input_format.md).
 
 ### Sample circuits
 
 A number of sample circuits are provided in
-[circuits](https://github.com/quantumlib/qsim/tree/master/circuits).
+[circuits](https://github.com/quantumlib/qsim/tree/main/circuits).
 
 ### Unit tests
 
 Unit tests for C++ libraries use the
 [GoogleTest](https://github.com/google/googletest) framework, and are located in
-[tests](https://github.com/quantumlib/qsim/tree/master/tests). Python tests use
+[tests](https://github.com/quantumlib/qsim/tree/main/tests). Python tests use
 [pytest](https://docs.pytest.org/en/stable/), and are located in
-[qsimcirq_tests](https://github.com/quantumlib/qsim/tree/master/qsimcirq_tests).
+[qsimcirq_tests](https://github.com/quantumlib/qsim/tree/main/qsimcirq_tests).
 
 To build and run all tests, run:
 

check/format-incremental

@@ -2,7 +2,7 @@
 
 ################################################################################
 # Based on the Cirq python-formatting script:
-# https://github.com/quantumlib/Cirq/blob/master/check/format-incremental
+# https://github.com/quantumlib/Cirq/blob/main/check/format-incremental
 #
 # Formats python files that have been modified.
 #
@@ -22,14 +22,14 @@
 #
 # You can specify a base git revision to compare against (i.e. to use when
 # determining whether or not a file is considered to have "changed"). For
-# example, you can compare against 'origin/master' or 'HEAD~1'.
+# example, you can compare against 'origin/main' or 'HEAD~1'.
 #
 # If you don't specify a base revision, the following defaults will be tried, in
 # order, until one exists:
 #
-#     1. upstream/master
-#     2. origin/master
-#     3. master
+#     1. upstream/main
+#     2. origin/main
+#     3. main
 #
 # If none exists, the script fails.
 ################################################################################
@@ -63,14 +63,14 @@ done
 if (( only_changed == 1 )); then
     # Figure out which branch to compare against.
     if [ -z "${rev}" ]; then
-        if [ "$(git cat-file -t upstream/master 2> /dev/null)" == "commit" ]; then
-            rev=upstream/master
-        elif [ "$(git cat-file -t origin/master 2> /dev/null)" == "commit" ]; then
-            rev=origin/master
-        elif [ "$(git cat-file -t master 2> /dev/null)" == "commit" ]; then
-            rev=master
+        if [ "$(git cat-file -t upstream/main 2> /dev/null)" == "commit" ]; then
+            rev=upstream/main
+        elif [ "$(git cat-file -t origin/main 2> /dev/null)" == "commit" ]; then
+            rev=origin/main
+        elif [ "$(git cat-file -t main 2> /dev/null)" == "commit" ]; then
+            rev=main
         else
-            echo -e "\033[31mNo default revision found to compare against. Argument #1 must be what to diff against (e.g. 'origin/master' or 'HEAD~1').\033[0m" >&2
+            echo -e "\033[31mNo default revision found to compare against. Argument #1 must be what to diff against (e.g. 'origin/main' or 'HEAD~1').\033[0m" >&2
             exit 1
         fi
     fi

docs/_scripts/build_api_docs.py

@@ -27,7 +27,7 @@
 
 flags.DEFINE_string(
     "code_url_prefix",
-    ("https://github.com/quantumlib/qsim/tree/master/" "qsimcirq"),
+    ("https://github.com/quantumlib/qsim/tree/main/" "qsimcirq"),
     "The url prefix for links to code.",
 )
 

docs/cirq_interface.md

@@ -44,7 +44,7 @@ directory.
 make run-py-tests
 ```
 This will run
-[qsimcirq_test](https://github.com/quantumlib/qsim/blob/master/qsimcirq_tests/qsimcirq_test.py),
+[qsimcirq_test](https://github.com/quantumlib/qsim/blob/main/qsimcirq_tests/qsimcirq_test.py),
 which invokes qsim through the qsim-Cirq interface.
 
 ## Interface design and operations
@@ -79,7 +79,7 @@ average PC, or up to 40 qubits on high-performance VMs).
 Options for the simulator, including number of threads and verbosity, can be
 set with the `qsim_options` field, which accepts a `QSimOptions` object as
 defined in
-[qsim_simulator.py](https://github.com/quantumlib/qsim/blob/master/qsimcirq/qsim_simulator.py).
+[qsim_simulator.py](https://github.com/quantumlib/qsim/blob/main/qsimcirq/qsim_simulator.py).
 These options can also be passed as a {str: val} dict, using the format
 described by that class.
 

docs/input_format.md

@@ -15,7 +15,7 @@ time gate_name qubits parameters
 Here `time` refers to when the gate is applied in the circuit. Gates with the same time can be
 applied independently and they may be reordered for performance. Trailing
 spaces or characters are not allowed. A number of sample circuits are provided
-in [circuits](https://github.com/quantumlib/qsim/blob/master/circuits).
+in [circuits](https://github.com/quantumlib/qsim/blob/main/circuits).
 
 # Supported gates
 

docs/install_qsimcirq.md

@@ -5,7 +5,7 @@ For all others, Dockerfiles are provided to install qsim in a containerized
 environment.
 
 **Note:** The core qsim library (under
-[lib/](https://github.com/quantumlib/qsim/blob/master/lib)) can be included
+[lib/](https://github.com/quantumlib/qsim/blob/main/lib)) can be included
 directly in C++ code without building and installing the qsimcirq interface.
 
 ## Before installation
@@ -14,12 +14,12 @@ Prior to installation, consider opening a
 [virtual environment](https://packaging.python.org/guides/installing-using-pip-and-virtual-environments/).
 
 Prerequisites are included in the
-[`requirements.txt`](https://github.com/quantumlib/qsim/blob/master/requirements.txt)
+[`requirements.txt`](https://github.com/quantumlib/qsim/blob/main/requirements.txt)
 file, and will be automatically installed along with qsimcirq.
 
 If you'd like to develop qsimcirq, a separate set of dependencies are includes
 in the
-[`dev-requirements.txt`](https://github.com/quantumlib/qsim/blob/master/dev-requirements.txt)
+[`dev-requirements.txt`](https://github.com/quantumlib/qsim/blob/main/dev-requirements.txt)
 file. You can install them with `pip3 install -r dev-requirements.txt` or
 `pip3 install qsimcirq[dev]`.
 

docs/overview.md

@@ -13,9 +13,9 @@ of qsim in cross-entropy benchmarks
 
 Integration with [Cirq](https://github.com/quantumlib/Cirq) makes getting
 started with qsim easy! Check out the
-[installation guide](https://github.com/quantumlib/qsim/blob/master/docs/install_qsimcirq.md)
+[installation guide](https://github.com/quantumlib/qsim/blob/main/docs/install_qsimcirq.md)
 or try the runnable
-[notebook tutorial](https://github.com/quantumlib/qsim/blob/master/docs/tutorials/qsimcirq.ipynb).
+[notebook tutorial](https://github.com/quantumlib/qsim/blob/main/docs/tutorials/qsimcirq.ipynb).
 
 ## Design
 

docs/tutorials/gcp_cpu.md

@@ -227,7 +227,7 @@ Instances dashboard to prevent further billing.
 
 You are now ready to run your own large simulations on Google Cloud. If you want
 to try a large circuit on Google Cloud, you can connect the
-[Simulate a large quantum circuit](https://colab.sandbox.google.com/github/quantumlib/qsim/blob/master/docs/tutorials/q32d14.ipynb)
+[Simulate a large quantum circuit](https://colab.sandbox.google.com/github/quantumlib/qsim/blob/main/docs/tutorials/q32d14.ipynb)
 Colab notebook to your VM
 ([documentation](https://quantumai.google/qsim/tutorials/q32d14)).
 

docs/tutorials/noisy_qsimcirq.ipynb

@@ -59,10 +59,10 @@
     "    <a target=\"_blank\" href=\"https://quantumai.google/qsim/tutorials/noisy_qsimcirq\"><img src=\"https://quantumai.google/site-assets/images/buttons/quantumai_logo_1x.png\" />View on QuantumAI</a>\n",
     "  </td>\n",
     "  <td>\n",
-    "    <a target=\"_blank\" href=\"https://colab.research.google.com/github/quantumlib/qsim/blob/master/docs/tutorials/noisy_qsimcirq.ipynb\"><img src=\"https://quantumai.google/site-assets/images/buttons/colab_logo_1x.png\" />Run in Google Colab</a>\n",
+  "    <a target=\"_blank\" href=\"https://colab.research.google.com/github/quantumlib/qsim/blob/main/docs/tutorials/noisy_qsimcirq.ipynb\"><img src=\"https://quantumai.google/site-assets/images/buttons/colab_logo_1x.png\" />Run in Google Colab</a>\n",
     "  </td>\n",
     "  <td>\n",
-    "    <a target=\"_blank\" href=\"https://github.com/quantumlib/qsim/blob/master/docs/tutorials/noisy_qsimcirq.ipynb\"><img src=\"https://quantumai.google/site-assets/images/buttons/github_logo_1x.png\" />View source on GitHub</a>\n",
+  "    <a target=\"_blank\" href=\"https://github.com/quantumlib/qsim/blob/main/docs/tutorials/noisy_qsimcirq.ipynb\"><img src=\"https://quantumai.google/site-assets/images/buttons/github_logo_1x.png\" />View source on GitHub</a>\n",
     "  </td>\n",
     "  <td>\n",
     "    <a href=\"https://storage.googleapis.com/tensorflow_docs/qsim/docs/tutorials/noisy_qsimcirq.ipynb\"><img src=\"https://quantumai.google/site-assets/images/buttons/download_icon_1x.png\" />Download notebook</a>\n",

docs/tutorials/q32d14.ipynb

@@ -51,10 +51,10 @@
     "    <a target=\"_blank\" href=\"https://quantumai.google/qsim/tutorials/q32d14\"><img src=\"https://quantumai.google/site-assets/images/buttons/quantumai_logo_1x.png\" />View on QuantumAI</a>\n",
     "  </td>\n",
     "  <td>\n",
-    "    <a target=\"_blank\" href=\"https://colab.research.google.com/github/quantumlib/qsim/blob/master/docs/tutorials/q32d14.ipynb\"><img src=\"https://quantumai.google/site-assets/images/buttons/colab_logo_1x.png\" />Run in Google Colab</a>\n",
+"    <a target=\\"_blank\\" href=\\"https://colab.research.google.com/github/quantumlib/qsim/blob/main/docs/tutorials/q32d14.ipynb\\"><img src=\\"https://quantumai.google/site-assets/images/buttons/colab_logo_1x.png\\" />Run in Google Colab</a>\n",
     "  </td>\n",
     "  <td>\n",
-    "    <a target=\"_blank\" href=\"https://github.com/quantumlib/qsim/blob/master/docs/tutorials/q32d14.ipynb\"><img src=\"https://quantumai.google/site-assets/images/buttons/github_logo_1x.png\" />View source on GitHub</a>\n",
+"    <a target=\\"_blank\\" href=\\"https://github.com/quantumlib/qsim/blob/main/docs/tutorials/q32d14.ipynb\\"><img src=\\"https://quantumai.google/site-assets/images/buttons/github_logo_1x.png\\" />View source on GitHub</a>\n",
     "  </td>\n",
     "  <td>\n",
     "    <a href=\"https://storage.googleapis.com/tensorflow_docs/qsim/docs/tutorials/q32d14.ipynb\"><img src=\"https://quantumai.google/site-assets/images/buttons/download_icon_1x.png\" />Download notebook</a>\n",

docs/tutorials/qsimcirq.ipynb

@@ -51,10 +51,10 @@
     "    <a target=\"_blank\" href=\"https://quantumai.google/qsim/tutorials/qsimcirq\"><img src=\"https://quantumai.google/site-assets/images/buttons/quantumai_logo_1x.png\" />View on QuantumAI</a>\n",
     "  </td>\n",
     "  <td>\n",
-    "    <a target=\"_blank\" href=\"https://colab.research.google.com/github/quantumlib/qsim/blob/master/docs/tutorials/qsimcirq.ipynb\"><img src=\"https://quantumai.google/site-assets/images/buttons/colab_logo_1x.png\" />Run in Google Colab</a>\n",
+"    <a target=\\"_blank\\" href=\\"https://colab.research.google.com/github/quantumlib/qsim/blob/main/docs/tutorials/qsimcirq.ipynb\\"><img src=\\"https://quantumai.google/site-assets/images/buttons/colab_logo_1x.png\\" />Run in Google Colab</a>\n",
     "  </td>\n",
     "  <td>\n",
-    "    <a target=\"_blank\" href=\"https://github.com/quantumlib/qsim/blob/master/docs/tutorials/qsimcirq.ipynb\"><img src=\"https://quantumai.google/site-assets/images/buttons/github_logo_1x.png\" />View source on GitHub</a>\n",
+"    <a target=\\"_blank\\" href=\\"https://github.com/quantumlib/qsim/blob/main/docs/tutorials/qsimcirq.ipynb\\"><img src=\\"https://quantumai.google/site-assets/images/buttons/github_logo_1x.png\\" />View source on GitHub</a>\n",
     "  </td>\n",
     "  <td>\n",
     "    <a href=\"https://storage.googleapis.com/tensorflow_docs/qsim/docs/tutorials/qsimcirq.ipynb\"><img src=\"https://quantumai.google/site-assets/images/buttons/download_icon_1x.png\" />Download notebook</a>\n",
@@ -109,7 +109,7 @@
     "id": "7lYC4qxpDKMN"
    },
    "source": [
-    "Simulating Cirq circuits with qsim is easy: just define the circuit as you normally would, then create a `QSimSimulator` to perform the simulation. This object implements Cirq's [simulator.py](https://github.com/quantumlib/Cirq/blob/master/cirq-core/cirq/sim/simulator.py) interfaces, so you can drop it in anywhere the basic Cirq simulator is used."
+"Simulating Cirq circuits with qsim is easy: just define the circuit as you normally would, then create a `QSimSimulator` to perform the simulation. This object implements Cirq's [simulator.py](https://github.com/quantumlib/Cirq/blob/main/cirq-core/cirq/sim/simulator.py) interfaces, so you can drop it in anywhere the basic Cirq simulator is used."
    ]
   },
   {
@@ -354,7 +354,7 @@
     "id": "OUjhKoRVZGKZ"
    },
    "source": [
-    "qsim performance can be tuned further by passing options to the simulator constructor. These options use the same format as the qsim_base binary - a full description can be found in the qsim [usage doc](https://github.com/quantumlib/qsim/blob/master/docs/usage.md). The example below demonstrates enabling multithreading in qsim; for best performance, use the same number of threads as the number of cores (or virtual cores) on your machine."
+"qsim performance can be tuned further by passing options to the simulator constructor. These options use the same format as the qsim_base binary - a full description can be found in the qsim [usage doc](https://github.com/quantumlib/qsim/blob/main/docs/usage.md). The example below demonstrates enabling multithreading in qsim; for best performance, use the same number of threads as the number of cores (or virtual cores) on your machine."
    ]
   },
   {
@@ -441,7 +441,7 @@
     "id": "KUAwCOGeu0wA"
    },
    "source": [
-    "In order to let qsimh know how we want to split up the circuit, we need to pass it some additional options. More detail on these can be found in the qsim [usage doc](https://github.com/quantumlib/qsim/blob/master/docs/usage.md), but the fundamentals are explained below."
+"In order to let qsimh know how we want to split up the circuit, we need to pass it some additional options. More detail on these can be found in the qsim [usage doc](https://github.com/quantumlib/qsim/blob/main/docs/usage.md), but the fundamentals are explained below."
    ]
   },
   {

docs/tutorials/qsimcirq_gcp.md

@@ -153,7 +153,7 @@ The container port is now forwarded to your local machine.
 ## Connect Colab to your local runtime
 
 First, get a notebook up and running on Colab. Open the
-<a target="_blank" class="external" href="https://colab.research.google.com/github/quantumlib/qsim/blob/master/docs/tutorials/qsimcirq.ipynb">Get started with qsimcirq</a>
+<a target="_blank" class="external" href="https://colab.research.google.com/github/quantumlib/qsim/blob/main/docs/tutorials/qsimcirq.ipynb">Get started with qsimcirq</a>
 notebook in Colab.
 
 If you are connect to Colab with a notebook visible, you can click *Connect* to
@@ -175,7 +175,7 @@ You should now be able to run the cells in the notebook.
 
 A large circuit is provided with 32 qubits and a depth of 14 gate operations.
 Open the
-<a target="_blank" class="external" href="https://colab.research.google.com/github/quantumlib/qsim/blob/master/docs/tutorials/q32d14.ipynb">Simulate large quantum circuit</a>
+<a target="_blank" class="external" href="https://colab.research.google.com/github/quantumlib/qsim/blob/main/docs/tutorials/q32d14.ipynb">Simulate large quantum circuit</a>
 notebook in Colab.
 
 This large circuit will not succeed if you attempt to run the default runtime.